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Bhutan Power Corporation Limited
Bhutan Power System Operator
Thimphu: Bhutan
Transmission System Performance Report
Second Quarterly Report – April to June, 2018
Transmission System Performance Report Second Quarterly Report-2018
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Table of Contents
1. INTRODUCTION ........................................................................................................................................ 2
2. NATIONAL PEAK DEMAND ..................................................................................................................... 2
2.1. POWER (MW) CONSUMED BY COUNTRY ............................................................................................................ 2
3. ENERGY AVAILABILITY AND REQUIREMENT FOR THE COUNTRY ............................................... 3
3.1. ENERGY (MU) CONSUMED BY COUNTRY ........................................................................................................... 3
4. PERFORMANCE OF GENERATING PLANTS ........................................................................................ 4
4.1. POWER AND ENERGY GENERATION ................................................................................................................... 4
4.2. PLANT CAPACITY FACTOR ................................................................................................................................. 4
5. EXPORT AND IMPORT OF ELECTRICITY ............................................................................................ 5
6. FREQUENCY PROFILE ............................................................................................................................. 6
6.1. FREQUENCY FOR THE MONTH OF APRIL, 2018 ................................................................................................... 6
6.2. FREQUENCY FOR THE MONTH OF MAY, 2018 ..................................................................................................... 7
6.3. FREQUENCY FOR THE MONTH OF JUNE, 2018 ..................................................................................................... 8
6.4. FREQUENCY SUMMARY FOR THE MONTH OF APRIL TO JUNE 2018 ..................................................................... 8
7. VOLTAGE PROFILE OF SELECTED SUBSTATION ............................................................................. 9
7.1. VOLTAGE PROFILE FOR THE MONTH OF APRIL, 2018 .......................................................................................... 9
7.2. VOLTAGE PROFILE FOR MONTH OF MAY, 2018. ............................................................................................... 10
7.3. VOLTAGE PROFILE FOR THE MONTH OF JUNE, 2018 ......................................................................................... 11
7.4. VOLTAGE SUMMARY FOR THE MONTH OF APRIL TO JUNE, 2018 ..................................................................... 12
8. MAJOR OUTAGES OF FEEDERS AND EQUIPMENT ......................................................................... 13
8.1 MAJOR OUTAGES IN EASTERN GRID ................................................................................................................ 13
8.2 MAJOR OUTAGES IN WESTERN GRID ............................................................................................................... 13
8.3 MAJOR OUTAGES OF GENERATING UNITS ......................................................................................................... 13
9. ANNEXURES ............................................................................................................................................. 14
Transmission System Performance Report Second Quarterly Report-2018
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1. Introduction
The electricity transmission network in Bhutan is solely owned by Bhutan Power Corporation limited (BPC) and electricity generation is solely
owned by Druk Green Power Corporation Limited (DGPC). Bhutan Power System Operator (BPSO) under BPC is responsible for safe, secure
and efficient operation of Bhutan transmission network and generation.
This quarterly report is prepared in compliance to the Grid Code Regulation (GCR) 2008, clause 6.14.1, “System Operator has to submit a
quarterly report covering the performance of the Transmission System to all Licensees, Authority and Ministry”. This transmission performance
report contains summary of growth of peak demand, performance of generating stations (power and energy generation), energy availability and
requirement for the country, export and import of electricity to/ from India, frequency profile of selected substation and voltage profile of few
important substations.
All the index and other calculations in this report have been executed based on the data received from substations and generating plants.
2. National Peak Demand
The national peak demand for the year 2018 is 375.23MW which was occurred on 24th February, 2018 at 18:34 hours. This is calculated by
summation of Feeder Loading at Plants minus Export.
Table 2.1. The growth in National Peak Demand since 2007
Year 2007 2008 2009 2010 2011 2012 2013 2014 2015 2016 2017 2018
Peak Load
(MW) 157.36 187.05 237.17 256.95 276.24 282.44 313.94 333.41 336.52 335.87 362.09 375.23
% Growth over
previous Year - 18.87 26.79 8.34 7.51 2.24 11.15 6.20 0.93 -0.19 7.81 3.63
Graph 2.1. The growth in National Peak Demand since 2007
2.1. Power (MW) consumed by country
Following methods are used to calculate peak demand for the Eastern Grid, Western Grid and National demand.
1. National Demand = (Sum of all total generation)-(Sum of all Export of Import)
2. National Demand = (Sum of all feeders loading at hydropower station) – (Sum of all Export/Import)
3. National Demand = (Sum of all substation loading)
For this report, the National Demand was calculated using method-2 and method-3.
Table 2.1.1. Domestic demand for Eastern Grid, Western Grid and National using method- 2
Grid Eastern Grid Load (MW) Western Grid Load (MW) National Load (MW)
Month Max Min Max Min Max Min
April 110.54 8.65 313.95 194.74 371.01 218.31
May 75.04 -2.95 324.86 45.29 372.46 88.23
June 98.05 3.64 327.71 173.78 372.72 134.62
157.36
187.05
237.17256.95
276.24 282.44
313.94333.41 336.52 335.87
362.09375.23
0
50
100
150
200
250
300
350
400
MW
Year
National Coincidental Peak Load (MW)
2007 2008 2009 2010 2011 2012 2013 2014 2015 2016 2017 2018
Transmission System Performance Report Second Quarterly Report-2018
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Graph 2.1.1. Domestic demand for Eastern Grid, Western Grid and National using method- 2
National load pattern for the month of April to June, 2018 calculated using method-2 is attached as Annexure-II.
Table 2.1.2. Domestic demand for Eastern Grid, Western Grid and National using method- 3
Grid Eastern Grid Load (MW) Western Grid Load (MW) National Load (MW)
Month Max Min Max Min Max Min
April 71.59 2.49 304.53 87.36 372.88 120.38
May 62.83 10.91 270.60 35.89 325.53 76.59
June 61.02 19.13 261.96 134.43 308.92 172.04
Graph 2.1.2. Domestic demand for Eastern Grid, Western Grid and National using method- 3
3. Energy Availability and Requirement for the country
3.1. Energy (MU) consumed by Country
The total energy consumed within Bhutan is computed from the total energy DGPC had sold to BPC including the royalty energy.
Table 3.1.1. Energy (MU) consumed
Month Total Ex-bus
(MU) Total Export/Import (MU) Total energy sold to BPC (MU)
April 255.02684710 57.63887072 193.26950656
May 511.71374551 307.78685685 196.61323709
June 702.54957524 509.05756900 186.09453364
-50.00
0.00
50.00
100.00
150.00
200.00
250.00
300.00
350.00
400.00
Max Min Max Min Max Min
Eastern Grid Load (MW) Western Grid Load (MW) National Load (MW)
Lo
ad
(M
W)
Load Summary
April
May
June
0.00
50.00
100.00
150.00
200.00
250.00
300.00
350.00
400.00
Max Min Max Min Max Min
Eastern Grid Load (MW) Western Grid Load (MW) National Load (MW)
Lo
ad
(M
W)
Load Summary
April
May
June
Transmission System Performance Report Second Quarterly Report-2018
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Graph 3.1.1. Energy (MU) consumed
4. Performance of generating plants
4.1. Power and Energy Generation
The maximum total generation for the Second quarter of year 2018 was 1751.97 MW in month of June which is increase of more than 50% from
first quarter of the year and minimum generation was 649.51 MW in the month of April, 2018.
Table: 4.1.1 Summary of maximum and minimum generation by various hydropower plant
Generation By BHP (MW) CHP (MW) THP (MW) KHP (MW) DHP (MW) TOTAL (MW)
Month Max Min Max Min Max Min Max Min Max Min Max Min
April 32.80 2.90 167.49 53.91 350.00 110.00 64.18 14.05 35.04 4.79 649.51 185.65
May 66.50 10.60 317.75 92.00 736.00 170.00 66.00 32.73 42.06 9.97 1,228.31 315.30
June 66.40 5.80 371.07 145.00 1,122.00 280.00 66.00 15.86 126.5 14.96 1,751.97 461.62
Graph: 4.1.1 Summary of maximum and minimum generation by various hydropower plant
Daily maximum, minimum and average generation by each generating plant for the month of April to June, 2018 is attached as Annexure-I.
4.2.Plant Capacity Factor
The capacity factor of each generating plant was calculated as below:
𝐶𝑎𝑝𝑎𝑐𝑖𝑡𝑦 𝑓𝑎𝑐𝑡𝑜𝑟 =𝑇𝑜𝑡𝑎𝑙 𝑒𝑛𝑒𝑟𝑔𝑦 𝑝𝑙𝑎𝑛𝑡 ℎ𝑎𝑠 𝑝𝑟𝑜𝑑𝑢𝑐𝑒 𝑜𝑣𝑒𝑟 𝑎 𝑝𝑒𝑟𝑖𝑜𝑑
𝑇𝑜𝑡𝑎𝑙 𝑒𝑛𝑒𝑟𝑔𝑦 𝑝𝑙𝑎𝑛𝑡 𝑤𝑜𝑢𝑙𝑑 𝑝𝑟𝑜𝑑𝑢𝑐𝑒 𝑤ℎ𝑒𝑛 𝑜𝑝𝑒𝑟𝑎𝑡𝑒𝑑 𝑎𝑡 𝑓𝑢𝑙𝑙 𝑐𝑎𝑝𝑎𝑐𝑖𝑡𝑦
Table 4.2.1: Total generation and capacity factor of various hydropower plants
Month BHP
(MU)
BHP
(CF) CHP (MU)
CHP
(CF) THP (MU)
THP
(CF)
KHP
(MU)
KHP
(CF)
DHP
(MU)
DHP
(CF)
April 9.98674 20.97% 70.53399 28.22% 144.956364 16.37% 23.454381 52.54% 6.095364 6.50%
May 18.59292 43.23% 145.06657 64.25% 291.40145 36.44% 39.857776 98.85% 16.79502 17.92%
June 25.08971 52.69% 198.68699 79.48% 407.05600 45.98% 45.381680 101.66% 26.335188 28.09%
Source: TD,
BPC
0.00000000
100.00000000
200.00000000
300.00000000
400.00000000
500.00000000
600.00000000
700.00000000
800.00000000
Total Ex-bus (MU) Total Export/Import(MU)
Total energy sold toBPC (MU)
Ene
rgy
(MU
)
Energy Consumptions
April
May
June
0.00
200.00
400.00
600.00
800.00
1,000.00
1,200.00
Max Min Max Min Max Min Max Min Max Min
BHP (MW) CHP (MW) THP (MW) KHP (MW) DHP (MW)
Gen
era
tio
n (
MW
)
Generation Summary
April
May
June
Transmission System Performance Report Second Quarterly Report-2018
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Graph 4.2.1: Capacity factor of various hydropower plants
5. Export and Import of Electricity
Maximum export for the Second quarter of year 2018 was 274MW to Binaguri substation in India. The minimum export was 0.10MW to
Salakoti and Rangia substation in India. There is increase of about 29% of generation export to India compare with that of export in first quarter
of the year.
Table 5.1. Export of electricity to India
Export To Binaguri (MW) Birpara (MW) Salakoti and Rangia (MW)
Month Max Min Max Min Max Min
April 274.00 1.00 63.00 0.40 39.50 0.10
May 622.00 82.00 196.20 2.00 73.80 0.10
June 1,065.00 178.00 302.40 22.40 155.00 9.50
Graph 5.1. Export of electricity to India
Table 5.2. Import of electricity from India.
Import
From Binaguri (MW) Birpara (MW) Salakoti and Rangia (MW)
Month Max Min Max Min Max Min
April 0.00 0.00 76.90 0.10 86.20 0.10
May 62.00 62.00 83.60 0.20 8.80 0.70
June 0.00 0.00 0.00 0.00 16.50 16.50
0.00%
20.00%
40.00%
60.00%
80.00%
100.00%
120.00%
BHP (CF) CHP (CF) THP (CF) KHP (CF) DHP (CF)
Ca
pa
city
Fa
cto
r
Plant Capacity Factor
April
May
June
0.00
200.00
400.00
600.00
800.00
1,000.00
1,200.00
Max Min Max Min Max Min
Binaguri (MW) Birpara (MW) Salakoti and Rangia
(MW)
Exp
ort
(M
W)
Export to India
April
May
June
Transmission System Performance Report Second Quarterly Report-2018
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Graph 5.2. Import of electricity from India
The maximum import of power for the Second quarter of year 2018 was 83MW from Birpara substation, India in the month of May, 2018.
6. Frequency profile
The nominal allowed frequency range shall be 50Hz ± 1% in Bhutan. The system is normally managed such that frequency is maintained within
operational limit of 49.5 Hz to 50.5 Hz. However, frequency may move outside these limit under faulty condition.
As per the Grid Code 2008, clause 6.4.1 the frequency is classified into three different bands as follows:
a. Normal state
The transmission System frequency is within the limit of 49.5Hz to 50.5Hz.
b. Alert state
The Transmission System frequency is beyond the normal operating limit but within 49.0Hz to 50.0Hz.
c. Emergency state
There is generation deficiency and frequency is below 49.0Hz.
The frequency at 220kV Bus at 220/66/11kV Semtokha substation in the western grid and 132kV Bus at 60MW Kurichhu Hydropower
Plant in the eastern grid is considered.
6.1.Frequency for the month of April, 2018
Table 6.1.1. Bus Frequency profile of Semtokha Substation
Sl. No. Operating State 220kV Bus Voltage
1 Normal State 99.19%
2 Alert State 0.13%
3 Emergency State 0.00%
4 Blackout/Other 0.67%
Graph 6.1.1. Bus Frequency of Semtokha Substation
Table 6.1.2. Bus frequency of Kurichhu Hydro Power Plant
Sl. No. Operating State 132kV Bus Voltage
1 Normal State 96.77%
2 Alert State 0.00%
3 Emergency State 0.00%
4 Blackout/Other 3.23%
0.00
10.00
20.00
30.00
40.00
50.00
60.00
70.00
80.00
90.00
100.00
Max Min Max Min Max Min
Binaguri (MW) Birpara (MW) Salakoti and Rangia
(MW)
Imp
ort
(M
W)
Import from India
April
May
June
99.19%
0.13%0.00%
0.67%
220kV Bus Frequency at Semtokha Substation
Normal State
Alert State
Emergency State
Blackout/Other
Transmission System Performance Report Second Quarterly Report-2018
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Graph 6.1.2. Bus frequency of Kurichhu Hydro Power Plant
In the month of April, 2018, the Western grid was maintained within the normal operating limit of 99.19% and deviated 0.13% and 0.67% to
alert and blackout state respectively. Eastern grid have operated 96.77% in operating limit and deviated 3.23% to alert state.
6.2.Frequency for the month of May, 2018
Table 6.2.1. Bus frequency of Semtokha Substation
Sl. No. Operating State 220kV Bus Voltage
1 Normal State 99.19%
2 Alert State 0.13%
3 Emergency State 0.00%
4 Blackout/Other 0.67%
Graph 6.2.1. Bus frequency of Semtokha Substation
Table 6.2.2. Bus frequency of Kurichhu Hydro Power Plant
Sl. No. Operating State 132kV Bus Voltage
1 Normal State 99.87%
2 Alert State 0.13%
3 Emergency State 0.00%
4 Blackout/Other 0.00%
Graph 6.2.2. Bus frequency of Kurichhu Hydro Power Plant
In the month of May, 2018, the Western gird frequency was maintained within the normal operating range of 99.19%. Eastern grid frequency
was maintained within normal operating range of 99.87% and system frequency was deviated 0.13% to alert state.
96.77%
0.00%
0.00%3.23%
132kV Bus Frequency at Kurichhu
Hydropower Plant
Normal State
Alert State
Emergency State
Blackout/Other
99.19%
0.13%0.00%
0.67%
220kV Bus Frequency at Semtokha Substation
Normal State
Alert State
Emergency State
Blackout/Other
99.87%
0.13%
0.00%
0.00%
132kV Bus Frequency at Kurichhu
Hydropower Plant
Normal State
Alert State
Emergency State
Blackout/Other
Transmission System Performance Report Second Quarterly Report-2018
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6.3.Frequency for the month of June, 2018
Table 6.3.1. Bus frequency of Semtokha Substation
Sl. No. Operating State 220kV Bus Voltage
1 Normal State 99.19%
2 Alert State 0.13%
3 Emergency State 0.00%
4 Blackout/Other 0.67%
Graph 6.3.1. Bus frequency of Semtokha Substation
Table 6.3.2. Bus frequency of Kurichhu Hydro Power Plant
Sl. No. Operating State 132kV Bus Voltage
1 Normal State 96.77%
2 Alert State 0.00%
3 Emergency State 0.00%
4 Blackout/Other 3.23%
Graph 6.3.2. Bus frequency of Kurichhu Hydro Power Plant
In the month of June, 2018, the Western gird frequency was maintained 99.19% within the normal operating range and deviated 0.13% to alert
state and 0.67% was blackout/others. Eastern grid frequency was maintained within normal operating range of 96.77% and system frequency
was deviated 3.23% to blackout/others.
6.4.Frequency Summary for the month of April to June 2018
Table 6.4.1. Frequency summary for the month of April to June, 2018
Substation/Plant Bus Frequency at Semtokha
Substation (Hz)
Bus Frequency at Kurichhu
Hydropower Plant (Hz)
Month Max Min Max Min
April 50.10 49.30 50.10 49.77
May 50.10 49.30 50.40 49.30
June 50.10 49.30 50.20 49.69
99.19%
0.13%0.00%
0.67%
220kV Bus Frequency at Semtokha Substation
Normal State
Alert State
Emergency State
Blackout/Other
96.77%
0.00%
0.00%
3.23%
132kV Bus Frequency at Kurichhu
Hydropower Plant
Normal State
Alert State
Emergency State
Blackout/Other
Transmission System Performance Report Second Quarterly Report-2018
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Graph 6.4.1. Frequency summary for the month of April to June, 2018
Daily maximum, minimum and average Frequency of Semtokha substation in western grid and Kurichhu Hydro Power Plant in eastern grid for
the month of April to June, 2018 is attached as Annexure-III
7. Voltage Profile of selected substation
As per the Grid Code 2008, clause 6.4.1 the voltage at all connection point is classified into three different bands as follows:
1. Normal State
The voltage at all connection points are within the limits of 0.95 times and 1.05 times of the normal values
2. Alert State
The voltage at all connection points are outside the normal limit but within the limits of 0.9 times and 1.1 times of the nominal values.
3. Emergency State
Transmission system voltages are outside the limit of 0.9 times and 1.1 times of nominal values.
Due to the location of 400/22/66/11kV Malbase substation in western grid and 132/33/11kV Nangkhor substation in the eastern grid, the
voltage profile of these substations are considered.
7.1.Voltage profile for the month of April, 2018
Table 7.1.1. Voltage Profile for 400/220/66kV Malbase Substation
Sl. No. Operating State 400kV Bus Voltage 220kV Bus Voltage 66kV Bus Voltage
1 Normal State 96.77% 96.77% 95.56%
2 Alert State 0.00% 0.00% 1.21%
3 Emergency State 0.00% 0.00% 0.00%
4 Blackout/Other 3.23% 3.23% 3.23%
Graph 7.1.1. Voltage Profile for 400/220/66kV Malbase Substation
Table 7.1.2. Voltage Profile of 220/66/11kV Semtokha Substation
Sl. No. Operating State 220kV Bus Voltage 66kV Bus Voltage
1 Normal State 96.64% 96.37%
2 Alert State 0.00% 0.00%
3 Emergency State 0.00% 0.27%
4 Blackout/Other 3.36% 3.36%
48.60
48.80
49.00
49.20
49.40
49.60
49.80
50.00
50.20
50.40
50.60
Max Min Max Min
Bus Frequency at Semtokha
Substation (Hz)
Bus Frequency at Kurichhu
Hydropower Plant (Hz)
Fre
qu
ency
(H
z)
Frequency Profile
April
May
June
96.77%
0.00%
0.00%3.23%
400kV Bus Voltage at Malbase
Substation
Normal State
Alert State
EmergencyState
Blackout/Other
96.77%
0.00%
0.00%3.23%
220kV Bus Voltage at Malbase
Substation
Normal State
Alert State
EmergencyStateBlackout/Other
Transmission System Performance Report Second Quarterly Report-2018
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Graph 7.1.2. Voltage Profile of 220/66/11kV Semtokha Substation
Table 7.1.3. Voltage Profile of 132/33/11kV Nangkhor Substation
Sl. No. Operating State 132kV Bus Voltage
1 Normal State 94.35%
2 Alert State 2.28%
3 Emergency State 0.00%
4 Blackout/Other 3.36%
Graph 7.1.3. Voltage Profile of 132/33/11kV Nangkor Substation
7.2.Voltage Profile for month of May, 2018.
Table 7.2.1. Voltage Profile for 400/220/66kV Malbase Substation
Sl. No. Operating State 400kV Bus Voltage 220kV Bus Voltage 66kV Bus Voltage
1 Normal State 100.00% 100.00% 98.66%
2 Alert State 0.00% 0.00% 0.40%
3 Emergency State 0.00% 0.00% 0.40%
4 Blackout/Other 0.00% 0.00% 0.54%
Graph 7.2.1. Voltage Profile for 400/220/66kV Malbase Substation
Table 7.2.2. Voltage Profile of 220/66/11kV Semtokha Substation
Sl. No. Operating State 220kV Bus Voltage 66kV Bus Voltage
1 Normal State 99.73% 99.87%
2 Alert State 0.13% 0.00%
3 Emergency State 0.13% 0.13%
4 Blackout/Other 0.00% 0.00%
96.64%
0.00%
0.00%3.36%
220kV Bus Voltage at Semtokha Substation
Normal State
Alert State
EmergencyState
Blackout/Other
96.37%
0.00%
0.27%3.36%
66kV Bus Voltage at Semtokha Substation
Normal State
Alert State
EmergencyState
Blackout/Other
94.35%
2.28%
0.00%
3.36%
132kV Bus Voltage at Nangkhor
Substation
Normal State
Alert State
EmergencyStateBlackout/Other
100.00%
0.00%
0.00%
0.00%
400kV Bus Voltage at Malbase Substation
Normal State
Alert State
EmergencyStateBlackout/Other
100.00%
0.00%
0.00%
0.00%
220kV Bus Voltage at Malbase Substation
Normal State
Alert State
Emergency State
Blackout/Other
Transmission System Performance Report Second Quarterly Report-2018
11 | P a g e
Graph 7.2.2. Voltage Profile of 220/66/11kV Semtokha Substation
Table 7.2.3. Voltage Profile of 132/33/11kV Nangkhor Substation
Sl. No. Operating State 132kV Bus Voltage
1 Normal State 100.00%
2 Alert State 0.00%
3 Emergency State 0.00%
4 Blackout/Other 0.00%
Graph 7.2.3. Voltage Profile of 132/33/11kV Nangkhor Substation
7.3.Voltage Profile for the month of June, 2018
Table 7.3.1. Voltage Profile for 400/220/66kV Malbase Substation
Sl. No. Operating State 400kV Bus Voltage 220kV Bus Voltage 66kV Bus Voltage
1 Normal State 96.77% 96.77% 95.83%
2 Alert State 0.00% 0.00% 0.94%
3 Emergency State 0.00% 0.00% 0.00%
4 Blackout/Other 3.23% 3.23% 3.23%
Graph 7.3.1. Voltage Profile for 400/220/66kV Malbase Substation
Table 7.3.2. Voltage Profile of 220/66/11kV Semtokha Substation
Sl. No. Operating State 220kV Bus
Voltage
66kV Bus
Voltage
1 Normal State 99.60% 99.46%
2 Alert State 0.00% 0.00%
3 Emergency State 0.00% 0.00%
4 Blackout/Other 0.40% 0.54%
99.73%
0.13%
0.13%0.00%
220kV Bus Voltage at Semtokha Substation
Normal State
Alert State
EmergencyStateBlackout/Other
99.87%
0.00%
0.13%0.00%
66kV Bus Voltage at Semtokha Substation
Normal State
Alert State
EmergencyStateBlackout/Other
100.00%
0.00%0.00%
0.00%
132kV Bus Voltage at Nangkhor
Substation
Normal State
Alert State
EmergencyStateBlackout/Other
96.77%
0.00%
0.00%3.23%
400kV Bus Voltage at Malbase Substation
Normal State
Alert State
Emergency State
Blackout/Other 96.77%
0.00%
0.00%3.23%
220kV Bus Voltage at Malbase Substation
Normal State
Alert State
Emergency State
Blackout/Other
Transmission System Performance Report Second Quarterly Report-2018
12 | P a g e
Graph 7.3.2. Voltage Profile of 220/66/11kV Semtokha Substation
Table 7.3.3. Voltage Profile of 132/33/11kV Nangkhor Substation
Sl. No. Operating State 132kV Bus Voltage
1 Normal State 96.64%
2 Alert State 0.00%
3 Emergency State 0.00%
4 Blackout/Other 3.36%
Graph 7.3.3. Voltage Profile of 132/33/11kV Nangkhor Substation
7.4.Voltage Summary for the Month of April to June, 2018
Table 7.4.1. Voltage Summary for the month of April to June, 2018
Substation Malbase Substation Nangkhor Substation
Voltage
Level 400kV Bus Voltage (kV) 220kV Bus Voltage (kV) 66kV Bus Voltage (kV) 132kV Bus Voltage (kV)
Month Max Min Max Min Max Min Max Min
April 420.00 399.50 230.00 217.00 68.00 62.00 141.51 128.20
May 420.00 397.00 230.00 216.00 67.00 57.50 138.60 127.30
June 415.00 394.50 227.50 213.50 67.00 62.00 138.10 130.10
Graph 7.4.1. Voltage Summary for the month of April to June, 2018
99.60%
0.00%
0.00%0.40%
220kV Bus Voltage at Semtokha
Substation
Normal State
Alert State99.46%
0.00%
0.00%0.54%
66kV Bus Voltage at Semtokha Substation
Normal State
Alert State
96.64%
0.00%
0.00%
3.36%
132kV Bus Voltage at Nangkhor
Substation
Normal State
Alert State
EmergencyState
Blackout/Other
0.00
50.00
100.00
150.00
200.00
250.00
300.00
350.00
400.00
450.00
Max Min Max Min Max Min Max Min
400kV Bus Voltage (kV) 220kV Bus Voltage (kV) 66kV Bus Voltage (kV) 132kV Bus Voltage (kV)
Malbase Substation Nangkhor Substation
Vo
lta
ge
(kV
)
Voltage Profile
April
May
June
Transmission System Performance Report Second Quarterly Report-2018
13 | P a g e
Daily maximum, minimum and average bus voltage of Malbase substation in western grid and Nangkhor substation in eastern grid for the month
of April to June, 2018 is attached as Annexure-IV
8. Major Outages of Feeders and Equipment
The transmission lines and equipment which was shut down for annual maintenance are not considered in the report. For second quarter of the
year, generally all the tripping are of transient in nature.
8.1 Major Outages in Eastern Grid
Following are the longest outages in Eastern Grid for the Second quarter of 2018:
i. 132kV Jigmeling-Gelephu and Gelephu-Salakati feeder was out of service for 5 hour and 39 minutes affecting Gelephu town which
happened on 4th June, 2018. The blackout time could have minimized if the relay at Gelephu substation had operate when there was a
power flow of around 139 MW during that instant which led to sever stain cutting of conductor and minor damage to the switchgear
equipment. Detail report was circulated to all the relevant stakeholder from BPSO office via letter number
02/BPC/BPSO/PSOD/VOL-1/18/95
The feeders and equipment outages for the Eastern grid is attached as Annexure-V.
8.2 Major Outages in Western Grid
Following are the longest outages in Western Grid for the Second quarter of 2018:
i. There was no longer duration outages of 400kV and 220kV voltage level transmission line recorded for second quarter of the year.
66kV Gomtu-Phuentsholing and Phentsholing-Malbase line was affected for 21 hours & 27 minutes and 252 hours & 59 minutes
respectively due to fire breakdown at 66/33/11 kV Phuentsholing substation during May month.
ii. Other than transmission line, 220 kV and 66kV Bus Coupler at Malbase Substation was out of service for few days during the month
of May, 2018.
The feeders and equipment outages for the Western grid is attached as Annexure-VI.
8.3 Major Outages of generating units
Following are some instances of generating unit tripping occurred in second quarter of the year:
i. All the running unit of CHP tripped on MOSD operation at 14.05 hrs on 4th June, 2018 due to transient fault along the 220kV CHP-
Birpara line.
ii. All the running unit of CHP tripped at 21.56 hrs on 19th June, 2018 due to SEF (Sensitive Earth Fault) operation. Unit number 2 & 3
restored at 22:34 hrs and 22:22 hrs respectively where other two units restored lately due to mechanical failure of Needle opening and
mal operation of relays.
iii. All the units of KHP tripped on 29th, June 2018 due to tripping of 132 kV line emanating from KHP at their respective end where no
relay and alarm operated at KHP. The tripping was took for about 35 minutes in average which cost around loss of 0.034 MU of
generation.
Transmission System Performance Report Second Quarterly Report-2018
14 | P a g e
9. Annexures
Annexure-I
Table: Generation of April, 2018
Graph: Generation for the month of April, 2018
Apr-18
Date Max Min Ava Max Min Ava Max Min Ava Max Min Ava Max Min Ava
1 14.00 12.60 13.58 81.03 71.40 75.91 150.00 150.00 150.00 32.38 14.05 20.85 20.18 15.00 error
2 13.90 3.90 12.03 86.93 74.02 78.80 170.00 150.00 153.33 32.40 14.11 21.59 16.50 15.00 error
3 14.50 12.60 13.14 86.11 76.01 80.57 180.00 150.00 163.33 32.42 16.46 22.76 17.78 15.17 error
4 16.40 13.20 13.49 86.03 75.10 80.48 180.00 160.00 164.58 32.78 16.49 23.83 21.20 14.21 error
5 16.80 13.40 14.11 81.61 76.92 79.26 160.00 160.00 160.00 45.71 16.45 23.87 18.23 16.17 error
6 14.50 13.80 14.18 86.20 70.11 75.86 160.00 150.00 155.83 33.00 16.34 24.30 15.98 15.44 error
7 14.40 12.30 13.34 115.20 76.74 86.35 260.00 150.00 182.50 32.49 16.38 24.33 15.88 14.98 error
8 17.40 13.50 15.18 101.78 91.24 95.61 260.00 180.00 190.00 45.86 16.50 32.75 17.96 13.99 error
9 15.50 13.90 14.66 100.55 90.00 93.48 200.00 200.00 200.00 48.10 27.21 33.29 17.99 16.25 error
10 14.10 2.90 9.31 92.56 76.94 86.43 200.00 160.00 171.67 33.00 24.56 29.44 16.01 14.98 error
11 17.10 12.30 14.27 92.22 86.49 88.53 180.00 180.00 180.00 64.18 33.00 40.67 35.04 14.97 error
12 14.40 13.80 14.17 92.08 87.01 87.65 200.00 180.00 184.17 48.19 31.63 35.58 17.98 14.99 error
13 14.50 14.20 14.33 113.34 87.85 100.03 280.00 170.00 209.17 49.50 31.42 43.66 17.00 15.94 error
14 14.40 4.30 12.61 116.29 92.57 100.75 200.00 190.00 199.17 49.50 33.00 44.98 0.00 No Generationerror
15 14.20 9.00 12.94 102.02 71.71 84.07 200.00 170.00 175.00 39.71 34.18 36.45 0.00 No Generationerror
16 14.20 13.00 13.79 93.57 72.79 86.20 190.00 170.00 179.17 37.08 28.59 32.21 0.00 No Generationerror
17 19.10 13.50 16.21 112.69 76.56 97.98 240.00 170.00 185.42 49.50 28.59 34.91 0.00 No Generationerror
18 22.80 13.00 16.62 126.80 96.40 113.41 260.00 240.00 243.33 42.64 26.59 32.52 0.00 No Generationerror
19 14.70 13.60 13.87 132.21 100.70 110.06 260.00 210.00 227.08 32.76 24.28 29.13 0.00 No Generationerror
20 15.70 14.50 14.99 137.68 90.20 108.24 340.00 190.00 216.25 44.85 25.44 31.68 0.00 No Generationerror
21 14.40 13.90 14.17 167.49 112.65 133.32 340.00 220.00 282.92 49.50 28.88 40.21 0.00 No Generationerror
22 14.20 12.50 13.43 132.20 112.46 120.24 270.00 220.00 245.00 48.50 33.00 38.86 0.00 No Generationerror
23 13.30 12.90 13.10 138.04 111.45 120.77 270.00 230.00 242.08 49.50 32.50 39.65 0.00 No Generationerror
24 13.00 12.40 12.77 122.75 112.22 116.59 330.00 200.00 235.00 48.81 33.00 38.17 0.00 No Generationerror
25 13.00 12.40 12.77 112.22 102.61 105.11 230.00 200.00 211.25 49.50 32.41 41.78 0.00 No Generationerror
26 15.50 8.00 12.83 123.39 86.20 102.71 220.00 200.00 205.00 33.00 27.83 31.27 0.00 No Generationerror
27 25.80 4.30 11.70 107.19 53.91 96.89 200.00 190.00 193.33 49.50 28.27 33.59 0.00 No Generationerror
28 15.50 3.30 10.04 102.85 96.58 100.14 210.00 200.00 206.25 47.86 25.58 30.77 4.79 4.79 error
29 19.30 14.40 16.04 116.09 102.69 107.22 220.00 210.00 212.08 36.98 25.58 29.50 28.54 16.96 error
30 32.80 17.10 24.93 139.23 104.00 118.20 350.00 110.00 258.75 49.50 30.37 35.01 27.56 16.97 error
31 0.00 No GenerationError 0.00 No GenerationError 0.00 No GenerationError 0.00 No GenerationError 0.00 No GenerationError
Max 32.80 167.49 350.00 64.18 35.04
Min 2.90 53.91 110.00 14.05 4.79
Source: THP, CHP, BHP, KHP (DGPC)
DHP (MW)BHP (MW) CHP (MW) THP (MW) KHP (MW)
Transmission System Performance Report Second Quarterly Report-2018
15 | P a g e
Table: Generation for the month of May, 2018
Graph: Generation for the month of May, 2018
May-18
Date Max Min Ava Max Min Ava Max Min Ava Max Min Ava Max Min Ava
1 32.60 21.50 26.10 228.07 121.06 170.01 460.00 250.00 358.75 66.00 33.00 47.45 42.06 24.04 error
2 33.20 21.90 28.33 195.04 145.22 174.66 380.00 300.00 352.50 66.00 41.18 54.05 35.05 19.99 error
3 33.20 22.80 29.54 198.41 161.61 175.94 430.00 240.00 345.83 41.40 36.94 39.85 35.04 12.95 error
4 33.10 24.90 29.20 190.48 157.21 172.76 370.00 330.00 345.42 64.84 39.26 49.08 25.04 20.92 error
5 28.60 20.60 25.17 204.14 167.87 181.36 380.00 300.00 350.42 45.67 32.77 39.35 28.05 21.97 error
6 28.30 20.70 23.51 223.17 159.45 192.15 480.00 300.00 387.92 66.00 32.73 46.21 26.04 20.95 error
7 28.20 19.90 23.88 238.02 191.08 210.42 490.00 370.00 430.83 66.00 37.97 46.01 26.06 20.95 error
8 25.70 19.40 21.18 276.90 193.26 239.35 550.00 370.00 490.00 66.00 37.96 60.02 23.04 20.05 error
9 20.00 11.20 17.29 229.50 195.04 208.42 440.00 380.00 399.17 66.00 47.64 61.12 22.00 17.02 error
10 17.20 14.60 16.20 275.40 92.00 210.56 500.00 210.00 376.67 49.50 45.29 47.37 20.94 16.99 error
11 24.30 10.60 18.28 250.48 149.97 176.24 450.00 300.00 350.42 66.00 43.52 54.94 23.02 17.00 error
12 18.40 15.50 16.48 179.80 152.62 159.58 350.00 300.00 305.83 49.50 32.90 41.19 19.99 17.00 error
13 15.30 14.30 14.88 152.93 140.22 142.98 300.00 270.00 287.50 48.20 33.00 36.24 18.00 14.97 error
14 38.40 14.30 19.52 174.42 129.92 148.21 340.00 270.00 293.75 49.50 33.00 37.29 17.97 9.97 error
15 35.30 17.00 23.20 222.79 142.71 162.18 380.00 280.00 347.08 66.00 34.47 46.80 33.10 19.91 error
16 32.70 19.00 24.48 158.30 144.94 152.75 320.00 280.00 291.67 66.00 36.91 45.33 29.06 20.01 error
17 57.90 18.80 30.85 185.30 144.29 169.32 400.00 280.00 328.33 45.55 37.24 39.79 20.04 17.98 error
18 65.30 25.90 40.52 252.35 173.90 215.50 530.00 360.00 445.00 66.00 37.51 50.41 23.02 18.50 error
19 66.50 39.00 54.20 258.69 173.48 217.29 490.00 320.00 432.08 66.00 49.50 63.52 39.00 26.00 error
20 62.60 28.50 40.00 271.59 193.06 244.32 600.00 440.00 496.67 66.00 49.50 61.19 39.00 20.00 error
21 44.90 25.50 33.10 216.00 192.63 200.96 390.00 260.00 376.88 66.00 49.50 60.38 37.00 22.00 error
22 31.30 22.60 25.40 229.10 181.03 204.26 480.00 380.00 416.67 64.49 52.86 60.38 28.00 20.94 error
23 39.80 24.50 30.58 236.89 188.89 213.16 540.00 170.00 442.17 66.00 57.10 65.29 36.07 25.03 error
24 32.50 25.70 29.15 286.81 204.48 249.83 736.00 374.00 522.88 66.00 66.00 66.00 40.96 24.82 error
25 33.30 17.10 25.54 317.75 230.35 276.94 680.00 480.00 577.92 66.00 66.00 66.00 36.05 21.99 error
26 23.30 23.10 23.11 290.85 235.40 256.32 670.00 430.00 510.00 66.00 66.00 66.00 24.02 21.95 error
27 26.00 19.80 21.63 260.56 213.10 229.55 490.00 440.00 462.50 66.00 66.00 66.00 22.53 18.03 error
28 20.00 17.40 18.60 263.58 189.71 224.07 530.00 400.00 444.58 66.00 66.00 66.00 20.00 17.00 error
29 18.70 17.10 17.87 241.11 178.90 205.93 440.00 380.00 417.50 66.00 64.90 65.95 20.02 17.46 error
30 27.40 18.70 22.46 197.07 158.76 182.99 440.00 260.00 365.00 66.00 33.00 63.14 22.01 17.97 error
31 20.70 18.10 19.31 175.62 155.91 165.60 370.00 320.00 337.92 66.00 33.00 58.22 19.22 17.68 18.52
Max 66.50 317.75 736.00 66.00 42.06
Min 10.60 92.00 170.00 32.73 9.97
Source: THP, CHP, BHP, KHP (DGPC)
BHP (MW) CHP (MW) THP (MW) KHP (MW) DHP (MW)
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16 | P a g e
Table: Generation for the month of June, 2018
Graph: Generation for the month of June, 2018
Jun-18
Date Max Min Ava Max Min Ava Max Min Ava Max Min Ava Max Min Ava
1 23.60 18.20 19.64 169.60 145.00 159.97 380.00 300.00 316.67 65.23 53.16 58.58 19.21 17.18 error
2 24.00 19.50 21.20 243.10 157.71 191.87 480.00 320.00 370.00 66.00 53.32 64.09 21.95 17.00 error
3 23.30 18.10 19.89 225.70 185.50 210.53 470.00 370.00 425.00 66.00 66.00 66.00 18.96 14.96 error
4 27.20 5.80 18.53 260.46 173.80 209.96 470.00 310.00 387.08 66.00 50.98 60.63 22.99 14.99 error
5 53.30 16.30 24.63 271.60 188.32 220.59 540.00 340.00 423.33 66.00 49.50 59.83 25.02 16.96 error
6 42.00 21.10 26.38 268.72 193.53 232.74 520.00 300.00 450.83 66.00 51.76 64.42 32.14 17.71 error
7 22.00 18.30 19.66 268.87 193.74 235.29 590.00 280.00 477.92 66.00 57.89 65.07 35.25 20.01 error
8 28.60 18.90 23.81 224.90 187.98 210.66 440.00 400.00 419.17 66.00 57.58 62.16 22.00 17.00 error
9 22.60 19.00 20.58 251.94 187.88 215.23 470.00 370.00 417.08 64.99 47.34 59.66 25.33 17.98 error
10 19.50 16.90 18.09 255.06 202.23 223.58 510.00 370.00 442.50 66.00 47.56 64.05 23.01 15.00 error
11 53.10 15.40 20.10 329.19 226.25 277.23 660.00 460.00 552.92 66.00 65.26 65.94 25.06 16.98 error
12 61.90 34.10 45.20 364.89 232.08 292.57 680.00 460.00 582.08 65.63 63.52 64.69 62.99 21.98 error
13 61.90 34.10 45.20 369.12 279.22 340.66 891.00 550.00 705.42 66.00 49.50 63.00 126.15 50.23 error
14 62.70 9.70 46.68 333.31 259.81 294.83 650.00 530.00 585.00 65.50 63.83 64.69 58.06 40.03 error
15 66.40 51.20 60.84 368.74 257.68 314.96 830.00 530.00 653.75 63.36 15.86 38.44 58.06 40.03 error
16 64.70 46.50 56.01 369.00 323.95 358.23 1,030.00 570.00 809.92 66.00 61.27 63.50 95.31 42.07 error
17 65.60 19.60 54.53 371.07 303.44 366.56 1,122.00 800.00 936.96 66.00 66.00 66.00 126.50 66.36 error
18 49.10 35.20 40.07 368.59 367.00 368.14 840.00 740.00 770.00 66.00 66.00 66.00 63.45 19.98 error
19 35.50 26.40 31.79 368.00 214.00 333.60 780.00 460.00 674.17 66.00 66.00 66.00 45.03 21.96 error
20 39.50 25.70 28.22 359.92 250.13 279.64 730.00 420.00 547.50 66.00 66.00 66.00 35.06 30.02 error
21 36.80 24.40 28.84 280.19 245.71 263.31 680.00 500.00 552.50 66.00 66.00 66.00 31.08 27.58 error
22 52.50 28.10 34.30 279.43 221.69 239.46 550.00 430.00 485.00 66.00 66.00 66.00 33.05 27.05 error
23 28.10 24.90 27.03 297.82 183.64 233.72 730.00 360.00 487.92 66.00 66.00 66.00 32.06 27.03 error
24 63.30 27.10 35.10 299.69 201.70 230.30 580.00 420.00 465.83 66.00 66.00 66.00 60.05 32.04 error
25 64.70 39.70 52.79 287.80 174.42 234.13 580.00 360.00 489.17 66.00 66.00 66.00 62.04 38.04 error
26 64.60 37.00 46.25 367.20 189.00 294.76 830.00 400.00 605.00 66.00 66.00 66.00 38.06 30.04 error
27 41.50 32.70 36.00 369.93 229.55 327.39 850.00 450.00 681.25 66.00 49.50 64.63 39.06 30.02 error
28 41.50 32.70 36.00 369.38 362.03 367.76 850.00 590.00 740.42 66.00 66.00 66.00 43.06 30.04 error
29 62.70 42.30 52.49 368.00 367.00 367.94 820.00 640.00 750.83 66.00 49.50 65.31 57.04 37.06 error
30 59.70 42.50 50.12 368.00 302.40 344.53 840.00 580.00 703.33 66.00 66.00 66.00 61.04 40.05 error
31 0.00 No GenerationError 0.00 No GenerationError 0.00 No GenerationError 0.00 No GenerationError 0.00 No GenerationError
Max 66.40 371.07 1,122.00 66.00 126.50
Min 5.80 145.00 280.00 15.86 14.96
Source: THP, CHP, BHP, KHP (DGPC)
DHP (MW)BHP (MW) CHP (MW) THP (MW) KHP (MW)
Transmission System Performance Report Second Quarterly Report-2018
17 | P a g e
Annexure-II
Table: National demand for April, 2018
Graph: National Demand for April, 2018
Apr-18 Max Min Ava
0:00 306.84 240.94 271.05
1:00 309.29 218.31 267.70
2:00 303.41 235.68 268.53
3:00 300.68 240.08 266.96
4:00 304.04 246.03 271.21
5:00 307.44 249.87 278.92
6:00 323.85 272.32 301.76
7:00 343.51 289.28 311.78
8:00 330.75 277.55 299.45
9:00 314.59 250.14 288.30
10:00 311.75 253.71 282.42
11:00 314.41 243.79 279.90
12:00 321.53 254.03 286.99
13:00 341.90 248.38 282.38
14:00 322.24 240.88 275.17
15:00 354.52 239.04 279.96
16:00 329.07 243.58 276.61
17:00 351.46 243.39 290.58
18:00 364.62 258.10 308.96
19:00 369.39 304.33 340.78
20:00 371.01 315.37 341.47
21:00 358.05 286.47 324.73
22:00 351.95 264.01 304.19
23:00 326.30 249.29 284.75
371.01
218.31
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18 | P a g e
Table: National Demand for May, 2018
Graph: National Demand for May, 2018
May-18 Max Min Ava
0:00 315.30 138.12 277.37
1:00 315.84 167.08 275.59
2:00 310.49 162.86 276.26
3:00 317.91 198.55 272.87
4:00 325.78 229.58 281.97
5:00 317.66 253.74 291.84
6:00 342.91 274.63 313.97
7:00 347.41 283.34 318.57
8:00 331.07 260.72 302.28
9:00 340.13 247.82 302.49
10:00 360.20 259.85 302.97
11:00 330.65 243.41 297.83
12:00 372.19 268.40 307.28
13:00 351.33 262.61 297.86
14:00 366.17 254.85 292.72
15:00 322.55 255.40 292.65
16:00 338.60 247.30 294.76
17:00 363.89 270.00 303.60
18:00 349.21 145.06 312.30
19:00 372.46 177.08 338.98
20:00 372.40 293.67 346.17
21:00 367.02 266.22 331.36
22:00 363.06 104.29 306.92
23:00 329.16 88.23 283.11
372.46
88.23
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19 | P a g e
Table: National Demand for June, 2018
Graph: National Demand for June, 2018
Jun-18 Max Min Ava
0:00 367.32 246.20 295.45
1:00 370.31 235.91 288.65
2:00 359.49 263.19 290.73
3:00 367.79 249.66 288.50
4:00 369.94 209.95 289.59
5:00 359.21 261.05 289.96
6:00 355.20 289.09 304.55
7:00 361.92 269.27 306.49
8:00 340.03 271.69 295.11
9:00 366.83 242.69 297.02
10:00 367.05 246.45 301.43
11:00 357.31 222.29 298.85
12:00 371.66 222.43 303.72
13:00 369.83 240.41 298.05
14:00 345.70 235.01 288.82
15:00 341.62 134.62 289.17
16:00 350.28 251.37 295.57
17:00 353.18 257.86 297.66
18:00 366.48 248.45 307.14
19:00 372.72 268.28 333.77
20:00 371.54 261.27 334.70
21:00 369.48 285.57 326.81
22:00 365.61 262.83 311.87
23:00 357.71 251.71 282.93
372.72
134.62
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Annexure-III
Table: Daily maximum, minimum and average frequency for the month of April, 2018
Graph: Daily maximum, minimum and average frequency for the month of April, 2018
Apr-18
Date Max Min Ava Max Min Ava
1 50.00 49.80 49.93 50.06 49.90 49.99
2 50.00 49.80 49.95 50.07 49.86 49.98
3 50.00 49.90 49.93 50.07 49.81 49.96
4 50.00 49.80 49.94 50.08 49.80 49.97
5 50.00 49.30 49.87 50.05 49.88 49.99
6 50.00 49.80 49.91 50.06 49.89 49.97
7 50.00 49.70 49.90 50.04 49.87 49.96
8 50.00 49.70 49.88 50.09 49.92 50.01
9 50.00 49.70 49.87 50.09 49.90 49.99
10 50.00 49.80 49.91 50.07 49.83 49.97
11 50.00 49.80 49.91 50.03 49.90 49.97
12 50.00 49.80 49.90 50.09 49.89 50.00
13 50.00 49.80 49.93 50.04 49.89 49.97
14 50.00 49.80 49.93 50.06 49.87 49.98
15 50.00 49.80 49.92 50.08 49.86 49.99
16 50.00 49.80 49.93 50.05 49.87 49.97
17 50.00 49.80 49.95 50.10 49.80 49.95
18 50.00 49.90 49.94 50.08 49.87 49.97
19 50.10 49.80 49.93 50.10 49.89 49.97
20 50.00 49.80 49.94 50.05 49.87 50.00
21 50.00 49.80 49.93 50.05 49.87 49.97
22 50.00 49.80 49.91 50.05 49.88 49.98
23 50.00 49.90 49.93 50.05 49.77 49.96
24 50.00 49.80 49.91 50.04 49.89 49.98
25 50.00 49.90 49.94 50.05 49.87 49.98
26 50.00 49.80 49.90 50.08 49.90 49.99
27 50.00 49.80 49.91 50.06 49.81 49.97
28 50.00 49.70 49.89 50.03 49.83 49.95
29 50.00 49.70 49.88 50.08 49.85 50.00
30 50.00 49.80 49.93 50.09 49.90 50.01
31 50.00 49.90 49.95 0.00 Error Error
Max 50.10 50.10
Min 49.30 49.77
Source: TD (BPC), KHP (DGPC)
Bus Frequency at Semtokha
Substation
Bus Frequency at Kurichhu
Hydropower Plant
48.00
48.50
49.00
49.50
50.00
50.50
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31
Fre
qu
ency
(H
z)
Date
Bus Frequency at Semtokha Substation and Kurichhu Hydropower Plant
SEM (Max)SEM (Min)SEM (Ava)KHP (Max)KHP (Min)KHP (Ava)
Transmission System Performance Report Second Quarterly Report-2018
21 | P a g e
Table: Daily maximum, minimum and average frequency for the month of May, 2018
Graph: Daily maximum, minimum and average frequency for the month of May, 2018
May-18
Date Max Min Ava Max Min Ava
1 50.00 49.80 49.93 50.05 49.90 50.00
2 50.00 49.80 49.95 50.06 49.94 50.01
3 50.00 49.90 49.93 50.14 49.85 50.02
4 50.00 49.80 49.94 50.04 49.78 49.95
5 50.00 49.30 49.87 50.03 49.76 49.93
6 50.00 49.80 49.91 50.40 49.76 50.01
7 50.00 49.70 49.90 50.06 49.78 49.96
8 50.00 49.70 49.88 50.10 49.85 49.98
9 50.00 49.70 49.87 50.07 49.80 49.95
10 50.00 49.80 49.91 50.00 49.70 49.90
11 50.00 49.80 49.91 50.06 49.83 49.94
12 50.00 49.80 49.90 50.07 49.82 49.96
13 50.00 49.80 49.93 50.07 49.90 49.98
14 50.00 49.80 49.93 50.10 49.83 50.00
15 50.00 49.80 49.92 50.04 49.30 49.93
16 50.00 49.80 49.93 50.10 49.82 49.94
17 50.00 49.80 49.95 50.06 49.86 49.95
18 50.00 49.90 49.94 50.03 49.73 49.90
19 50.10 49.80 49.93 50.03 49.71 49.90
20 50.00 49.80 49.94 50.02 49.82 49.96
21 50.00 49.80 49.93 50.10 49.75 49.95
22 50.00 49.80 49.91 50.04 49.67 49.91
23 50.00 49.90 49.93 50.09 49.85 49.96
24 50.00 49.80 49.91 50.06 49.79 49.96
25 50.00 49.90 49.94 50.04 49.85 49.98
26 50.00 49.80 49.90 50.04 49.75 49.92
27 50.00 49.80 49.91 50.09 49.84 49.96
28 50.00 49.70 49.89 50.05 49.72 49.94
29 50.00 49.70 49.88 50.06 49.87 49.99
30 50.00 49.80 49.93 50.06 49.78 49.95
31 50.00 49.90 49.95 50.01 49.80 49.92
Max 50.10 50.40
Min 49.30 49.30
Source: TD (BPC), KHP (DGPC)
Bus Frequency at Semtokha
Substation
Bus Frequency at Kurichhu
Hydropower Plant
48.00
48.50
49.00
49.50
50.00
50.50
51.00
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31
Fre
qu
ency
(H
z)
Date
Bus Frequency at Semtokha Substation and Kurichhu Hydropower
Plant
SEM (Max)
SEM (Min)
SEM (Ava)
KHP (Max)
KHP (Min)
KHP (Ava)
Transmission System Performance Report Second Quarterly Report-2018
22 | P a g e
Table: Daily maximum, minimum and average frequency for the month of June, 2018
Graph: Daily maximum, minimum and average frequency for the month of June, 2018
Jun-18
Date Max Min Ava Max Min Ava
1 50.00 49.80 49.93 50.14 49.79 49.99
2 50.00 49.80 49.95 50.09 49.90 50.00
3 50.00 49.90 49.93 50.14 49.90 50.01
4 50.00 49.80 49.94 50.05 49.83 49.95
5 50.00 49.30 49.87 50.04 49.79 49.95
6 50.00 49.80 49.91 50.05 49.83 49.98
7 50.00 49.70 49.90 50.07 49.86 49.99
8 50.00 49.70 49.88 50.06 49.90 50.01
9 50.00 49.70 49.87 50.20 49.90 50.01
10 50.00 49.80 49.91 50.11 49.90 50.01
11 50.00 49.80 49.91 50.05 49.90 50.00
12 50.00 49.80 49.90 50.10 49.91 49.99
13 50.00 49.80 49.93 50.09 49.85 49.97
14 50.00 49.80 49.93 50.05 49.72 49.94
15 50.00 49.80 49.92 50.05 49.80 49.97
16 50.00 49.80 49.93 50.10 49.90 50.00
17 50.00 49.80 49.95 50.12 49.90 50.01
18 50.00 49.90 49.94 50.07 49.69 49.97
19 50.10 49.80 49.93 50.04 49.81 49.94
20 50.00 49.80 49.94 50.04 49.70 49.91
21 50.00 49.80 49.93 50.05 49.82 49.94
22 50.00 49.80 49.91 50.05 49.83 49.98
23 50.00 49.90 49.93 50.06 49.89 49.98
24 50.00 49.80 49.91 50.10 49.88 49.99
25 50.00 49.90 49.94 50.09 49.93 50.00
26 50.00 49.80 49.90 50.10 49.90 50.00
27 50.00 49.80 49.91 50.10 49.86 50.01
28 50.00 49.70 49.89 50.07 49.87 49.98
29 50.00 49.70 49.88 50.05 49.83 49.97
30 50.00 49.80 49.93 50.05 49.83 49.94
31 50.00 49.90 49.95 0.00 Error Error
Max 50.10 50.20
Min 49.30 49.69
Source: TD (BPC), KHP (DGPC)
Bus Frequency at Semtokha
Substation
Bus Frequency at Kurichhu
Hydropower Plant
48.00
48.50
49.00
49.50
50.00
50.50
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30
Fre
qu
ency
(H
z)
Date
Bus Frequency at Semtokha Substation and Kurichhu
Hydropower Plant
SEM (Max)SEM (Min)SEM (Ava)KHP (Max)KHP (Min)KHP (Ava)
Transmission System Performance Report Second Quarterly Report-2018
23 | P a g e
Annexure-IV
Table: Daily maximum, minimum and average Voltage for the month of April, 2018
Graph: Daily maximum, minimum and average Voltage for the month of April, 2018
Date Max Min Ava Max Min Ava Max Min Ava Max Min Ava
1 416.00 404.50 412.77 228.00 221.00 226.10 66.00 63.00 65.13 137.56 131.10 134.49
2 417.00 403.00 411.10 228.00 218.50 224.42 66.00 63.00 64.83 137.77 129.40 134.49
3 415.00 400.50 410.65 227.00 217.00 223.77 66.00 62.00 64.38 138.19 128.40 133.75
4 414.50 400.50 409.04 226.50 217.50 222.81 66.00 63.00 64.17 136.30 129.04 133.01
5 414.00 406.00 411.19 226.00 221.50 224.31 66.00 63.00 64.54 138.10 132.30 134.95
6 420.00 401.50 412.25 230.00 218.50 224.79 66.00 62.00 64.79 138.80 132.00 135.40
7 416.00 403.50 411.44 228.00 220.50 224.25 66.00 63.00 64.71 137.70 130.91 134.22
8 418.00 401.50 411.06 228.00 219.00 224.73 66.00 63.00 64.75 139.00 129.80 134.56
9 414.00 402.00 409.42 227.50 219.00 223.98 66.00 63.00 64.83 137.14 129.60 133.68
10 415.50 404.00 410.88 227.50 221.00 225.10 66.00 63.00 65.33 136.20 128.20 133.69
11 417.00 405.00 411.73 230.00 221.50 225.96 67.00 64.00 65.21 138.20 131.50 135.23
12 417.00 403.50 411.10 228.50 220.00 225.21 68.00 63.00 64.96 138.80 129.25 134.81
13 415.00 402.00 410.67 229.00 220.00 225.33 66.00 63.00 64.83 138.80 133.40 135.69
14 414.00 402.00 410.08 228.00 221.00 225.44 66.00 63.00 65.00 139.20 134.40 136.42
15 416.00 403.00 410.81 228.00 219.50 225.25 66.00 63.00 64.58 139.01 133.00 136.46
16 414.00 400.50 409.25 228.00 218.00 224.33 66.00 62.00 64.42 136.73 130.40 135.04
17 414.00 401.00 409.81 227.00 218.50 224.58 66.00 62.00 64.67 138.20 131.10 135.37
18 417.50 405.50 411.29 227.00 221.00 224.83 66.00 64.00 64.67 138.10 131.70 135.41
19 419.00 405.00 412.83 228.00 220.50 225.44 66.00 63.00 65.25 138.30 132.00 135.43
20 416.50 404.00 412.98 228.00 221.00 225.98 66.00 64.00 65.29 138.40 131.90 136.08
21 417.50 401.00 411.42 228.50 220.00 225.56 66.00 64.00 65.21 140.20 131.00 135.87
22 418.00 403.00 413.04 230.00 218.00 225.63 66.00 63.00 64.96 138.81 130.50 135.95
23 415.00 399.50 409.15 227.00 218.50 223.17 66.00 62.00 64.29 136.50 129.60 134.52
24 413.50 402.00 407.58 226.50 220.00 223.27 65.00 63.00 64.33 137.98 130.90 134.93
25 416.00 404.50 410.15 228.50 221.50 225.06 68.00 64.00 65.58 141.51 132.99 135.94
26 418.00 406.50 410.23 229.00 223.00 226.38 67.00 64.00 65.77 139.20 131.50 135.86
27 417.00 405.00 411.54 230.00 220.00 225.10 66.00 63.00 64.83 138.60 130.50 134.54
28 417.00 402.50 409.17 228.00 220.00 223.75 66.00 64.00 64.96 137.50 132.00 134.93
29 418.00 402.50 410.44 229.50 221.00 225.69 67.00 64.00 65.25 139.01 131.10 135.99
30 415.50 408.50 411.25 228.50 223.00 225.88 66.00 64.00 65.29 137.35 130.90 134.21
31 0.00 Error Error 0.00 Error Error 0.00 Error Error 0.00 Error Error
Max 420.00 230.00 68.00 141.51
Min 399.50 217.00 62.00 128.20
Source: TD, BPC
Apr-18400kV Bus Voltage (kV) 132kV Bus Voltage (kV)66kV Bus Voltage (kV)
Malbase Substation Nangkhor Substation
220kV Bus Voltage (kV)
50.00
100.00
150.00
200.00
250.00
300.00
350.00
400.00
450.00
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30
Volt
age
(kV
)
Date
Bus Voltage at Malbase and Nangkhor Substation
400kV (Max)
400kV (Min)
400kV (Ava)
220kV (Max)
220kV (Min)
220kV (Ava)
66kV (Max)
66kV (Min)
66kV (Ava)
132kV (Max)
132kV (Min)
132kV (Ava)
Transmission System Performance Report Second Quarterly Report-2018
24 | P a g e
Table: Daily maximum, minimum and average Voltage for the month of May, 2018
Graph: Daily maximum, minimum and average Voltage for the month of May, 2018
Date Max Min Ava Max Min Ava Max Min Ava Max Min Ava
1 417.00 402.00 411.92 229.00 220.00 224.54 66.00 63.00 65.00 138.20 133.61 135.95
2 416.00 404.00 410.81 229.00 221.50 225.81 66.00 64.00 65.38 138.30 132.70 135.92
3 416.00 402.00 410.06 228.00 220.00 224.65 67.00 64.00 65.21 137.90 131.30 135.20
4 415.00 402.00 408.25 227.00 222.00 224.40 66.00 64.00 64.58 137.70 133.61 135.63
5 420.00 399.50 408.04 226.50 219.00 223.67 66.00 63.00 64.58 137.90 130.29 134.74
6 414.00 401.00 409.06 227.00 220.00 224.54 66.00 63.00 64.71 138.39 134.00 136.18
7 411.50 399.50 406.33 226.00 220.50 223.40 65.00 64.00 64.45 137.60 127.30 133.90
8 412.00 398.00 405.04 227.50 217.50 223.40 67.00 57.50 63.85 136.90 131.74 134.23
9 410.00 399.50 404.65 227.50 218.00 223.46 66.00 64.00 64.54 137.30 132.00 135.30
10 409.00 400.00 403.31 227.00 219.50 222.46 65.00 64.00 64.46 137.10 132.10 134.51
11 413.00 399.50 407.13 227.50 218.00 223.15 66.00 63.00 64.38 136.80 133.60 135.14
12 415.00 398.50 408.67 227.50 216.00 223.29 66.00 63.00 64.92 137.50 130.90 134.52
13 416.50 402.50 409.65 226.50 219.00 223.69 66.00 63.00 64.71 137.30 130.00 134.47
14 418.00 402.00 410.63 230.00 220.50 225.46 66.00 63.00 65.08 138.18 130.71 134.61
15 414.50 400.50 407.48 226.50 222.00 224.63 66.00 62.50 64.90 137.56 132.50 134.87
16 411.50 399.00 405.67 227.00 219.00 223.71 66.00 63.00 64.67 137.70 131.74 134.81
17 411.50 398.50 406.25 227.50 218.50 223.40 66.00 63.00 64.46 137.90 128.80 133.70
18 412.00 398.50 404.00 227.00 218.00 222.21 65.00 62.50 63.92 136.60 130.00 133.59
19 413.50 398.50 407.08 228.00 218.00 223.88 66.00 63.00 65.08 136.30 130.08 133.42
20 415.50 400.50 407.23 228.50 220.00 224.02 66.00 64.00 64.79 136.70 131.50 134.06
21 412.00 397.00 404.90 226.50 217.50 222.19 66.00 63.00 64.75 136.00 130.20 133.51
22 407.50 397.00 403.19 224.50 217.00 220.81 65.00 63.00 64.13 136.10 130.91 133.77
23 418.00 400.00 405.71 228.00 218.00 222.94 65.00 63.00 64.25 136.30 130.90 134.13
24 410.50 398.00 403.96 225.00 217.50 221.79 66.00 63.00 64.54 136.90 130.91 134.21
25 407.50 399.50 403.48 224.00 219.00 221.79 66.00 63.00 64.83 136.90 132.99 134.97
26 409.00 400.00 404.29 225.50 218.50 222.25 66.00 63.00 64.63 137.30 132.00 135.23
27 415.00 400.00 405.92 226.50 217.50 222.75 66.00 63.00 64.63 138.60 131.12 135.34
28 408.00 399.50 403.69 225.00 219.50 222.65 66.00 64.00 64.54 138.10 130.90 134.97
29 408.00 401.50 404.73 225.50 219.50 222.46 66.00 63.00 64.46 137.80 130.91 134.32
30 411.00 399.00 406.38 226.50 218.00 222.83 66.00 63.00 65.08 137.90 130.90 134.09
31 412.00 402.50 406.83 226.50 219.00 222.67 67.00 64.00 65.00 135.90 130.29 133.65
Max 420.00 230.00 67.00 138.60
Min 397.00 216.00 57.50 127.30
Source: TD, BPC
May-18400kV Bus Voltage (kV) 132kV Bus Voltage (kV)66kV Bus Voltage (kV)
Malbase Substation Nangkhor Substation
220kV Bus Voltage (kV)
50.00
100.00
150.00
200.00
250.00
300.00
350.00
400.00
450.00
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31
Volt
age
(kV
)
Date
Bus Voltage at Malbase and Nangkhor Substation
400kV (Max)400kV (Min)400kV (Ava)220kV (Max)220kV (Min)220kV (Ava)66kV (Max)66kV (Min)66kV (Ava)132kV (Max)132kV (Min)132kV (Ava)
Transmission System Performance Report Second Quarterly Report-2018
25 | P a g e
Table: Daily maximum, minimum and average Voltage for the month of June, 2018
Graph: Daily maximum, minimum and average Voltage for the month of June, 2018
Date Max Min Ava Max Min Ava Max Min Ava Max Min Ava
1 415.00 396.50 406.38 227.50 218.00 223.33 67.00 64.00 65.25 136.30 130.49 133.19
2 406.00 394.50 401.96 223.50 215.50 220.50 65.00 63.00 64.33 134.40 130.40 133.00
3 407.00 400.00 402.92 225.00 218.50 220.83 66.00 63.00 64.63 136.73 130.20 133.38
4 406.50 399.00 402.75 224.00 216.50 220.63 65.00 62.00 64.25 135.60 131.80 133.59
5 410.00 399.00 405.31 226.00 216.50 221.46 66.00 63.00 64.46 135.90 131.54 133.96
6 414.00 401.00 409.06 227.00 220.00 224.54 66.00 63.00 64.71 136.31 131.12 134.41
7 412.00 401.00 406.50 225.50 220.00 222.56 66.00 64.00 64.83 136.70 130.20 133.74
8 410.00 401.00 405.17 224.00 219.00 221.88 65.00 63.00 64.38 136.50 130.40 134.06
9 413.50 403.00 408.25 227.00 218.00 222.77 66.00 64.00 64.83 135.50 131.54 133.76
10 415.00 405.00 410.15 227.00 220.50 223.56 66.00 64.00 65.04 136.50 132.57 133.98
11 411.50 402.50 406.79 225.50 219.00 222.04 65.00 63.00 64.17 136.10 130.90 133.73
12 412.00 403.00 407.19 224.00 220.00 222.02 65.00 64.00 64.50 136.70 131.30 134.17
13 409.00 401.00 404.63 224.00 219.00 220.63 65.00 64.00 64.38 135.90 130.91 133.96
14 410.00 402.00 405.52 225.50 218.50 222.19 65.00 63.00 64.17 137.15 131.74 134.49
15 405.50 399.00 402.65 223.00 213.50 219.25 65.00 62.00 63.67 138.10 132.16 135.23
16 407.00 399.00 402.63 225.00 219.00 221.88 65.00 63.00 64.46 137.30 133.00 135.30
17 405.00 400.00 402.33 224.00 219.00 221.60 65.00 64.00 64.38 137.14 132.78 135.24
18 405.00 399.00 401.60 222.50 219.00 220.67 65.00 63.00 64.21 136.30 130.90 134.22
19 405.00 399.00 402.40 222.50 218.50 220.90 65.00 63.00 64.00 136.70 130.10 133.91
20 407.00 399.00 403.38 224.00 219.00 221.46 65.00 63.00 64.33 136.50 132.50 134.31
21 409.00 401.00 404.96 224.00 220.00 222.25 66.00 64.00 64.65 136.70 131.74 134.30
22 409.00 402.50 405.00 224.50 221.00 222.40 65.00 64.00 64.58 137.35 132.78 135.08
23 407.50 400.50 404.50 224.00 218.50 221.13 65.00 63.00 64.13 137.20 131.74 134.77
24 410.00 402.00 406.54 225.00 220.00 222.75 65.00 64.00 64.75 136.70 132.00 134.88
25 412.00 402.50 407.44 225.50 221.00 223.29 66.00 65.00 65.13 136.94 131.70 134.68
26 408.50 400.00 405.35 225.00 219.50 222.46 66.00 65.00 65.25 136.90 132.20 134.55
27 408.50 399.00 403.77 225.00 219.00 221.85 66.00 63.00 64.67 137.30 131.30 134.62
28 404.00 399.00 401.85 224.00 220.00 221.10 65.00 64.00 64.67 136.10 130.90 133.60
29 408.00 397.00 401.31 223.00 217.50 220.46 65.00 64.00 64.42 137.60 131.32 134.60
30 409.00 401.00 404.08 225.00 219.00 221.73 66.00 64.00 64.71 136.10 132.00 134.53
31 0.00 Error Error 0.00 Error Error 0.00 Error Error 0.00 Error Error
Max 415.00 227.50 67.00 138.10
Min 394.50 213.50 62.00 130.10
Source: TD, BPC
Jun-18400kV Bus Voltage (kV) 132kV Bus Voltage (kV)66kV Bus Voltage (kV)
Malbase Substation Nangkhor Substation
220kV Bus Voltage (kV)
50.00
100.00
150.00
200.00
250.00
300.00
350.00
400.00
450.00
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30
Volt
age
(kV
)
Date
Bus Voltage at Malbase and Nangkhor Substation
400kV (Max)400kV (Min)400kV (Ava)220kV (Max)220kV (Min)220kV (Ava)66kV (Max)66kV (Min)66kV (Ava)132kV (Max)132kV (Min)132kV (Ava)
Transmission System Performance Report Second Quarterly Report-2018
26 | P a g e
Annexure-V
Eastern Grid Outages
April, 2018
132/33/11kV, Kilikhar substation
Sl. NoDate of
Tripping
Time of
Outage
(Hrs)
Date of
Normalizati
on
Time of Fault
cleared (Hrs)
Duration of
Outages
Load before
Outage
(MW)
Name of Feeders
Tripped
Name of Substations/Line
affected by faultReason of Fault
Relay indication and
operation
Exact location of fault
(Line
segment/substation)
Remarks
1 01.04.2018 10.26 01.04.2018 10.4 0:14 3.700 132kV Kurichu I/C All Tripped on fault Nill Nganglam
Grid failed form Nanglam substation, Distance
relay oprt.65.33Km towards Nangkhor(zone
III).
2 05.04.2018 15.02 05.04.2018 15.2 0:18 3.130 132kV Kurichu I/C All
O/C on R&Y phase
zone 1 Distance
41.16km towards
Salakati
Nill Salakati
Grid failed form Salakati end, due to O/C on
R&Y phase zone 1 Distance 41.16km towards
Salakati .
3 18.04.2018 13.56 18.04.2018 13.38 0:03 2.800 132kV Kurichu I/C All Tripped on fault Nill Kurichu Supply failed from Kurichu end only relay 86
4 25.04.2018 16.07 25.04.2018 16.15 0:08 4.030 132kV Kurichu I/C All Tripped on fault Nill Rangia Grid failed from Rangia,due to bad weather
5 25.04.2018 16.19 25.04.2018 16.25 0:06 4.030 132kV Kurichu I/C All Tripped on fault NillTingtibi & Jimeling
end
Grid failed from Tingtibi and Jimeling,due to
bad weather
132/33/11kV, Kanglung substation
Sl. NoDate of
Tripping
Time of
Outage
(Hrs)
Date of
Normalizati
on
Time of Fault
cleared (Hrs)
Duration of
Outages
Load before
Outage
(MW)
Name of Feeders
Tripped
Name of Substations/Line
affected by faultReason of Fault
Relay indication and
operation
Exact location of fault
(Line
segment/substation)
Remarks
1 1/4/2018 10:26 1/4/2018 10:40 0:14 1.87 132KV Incomer ALL NA 86 relay Kurichu Grid failed form Nanglam substation, Distance
2 5/4/2018 15:02 5/4/2018 15:20 0:18 1.54 132kV Incomer ALL NA
O/C on R &Y phase,
Zone -1 , distance 41.16
km towards Salakati
Salakati
Grid failed form Salakati end, due to O/C on
R&Y phase zone 1 Distance 41.16km towards
Salakati .
3 7/4/2018 20:32 7/4/2018 20:35 0:03 4.98 132kV Incomer ALL CB Air pressure low NA Kanglung 132KV incomer SF6 breaker air pressure low
4 9/4/2018 22:45 9/4/208 22:47 0:02 2.45 132kV Incomer ALL CB Air pressure low NA Kanglung 132KV incomer SF6 breaker air pressure low
5 13/04/2018 22:33 13/04/2018 22:37 0:04 2.08 132kV Incomer ALL NA NA KurichuSupply tripped due to bad weather , charged
within 4mins.
132/33/11kV, Nangkor substation
Sl. NoDate of
Tripping
Time of
Outage
(Hrs)
Date of
Normalizati
on
Time of Fault
cleared (Hrs)
Duration of
Outages
Load before
Outage
(MW)
Name of Feeders
Tripped
Name of Substations/Line
affected by faultReason of Fault
Relay indication and
operation
Exact location of fault
(Line
segment/substation)
Remarks
1 01.04.2018 10:24 01.04.2018 10:40 0:16 0.5 132kV Nganglam All Tripped on faultDistance Protection
relay operated
Rangia Substation &
Nganglam substation
132kV Nangkor-Deothang CB didn't opened
at the instand of grid failure showing the fault
at 37.36km towards Deothang, zone 3, start
phase CN, fault resistance 1.928 ohms, IA-
104.7A, IB-55.05A, IC-1.103kA, VAN-
69.14kV, VBN-71.19kV, VCN-35.12kV.
Distance relay operated at Nganglam showing
the fault at a distance of 65.33km, zone 3
2 01.04.2018 10:37 01.04.2018 10:42 0:05 0.006132/33kV
Transformer-I
All 33kV & 11kV
FeedersTripped on fault
Differential Protection
Relay 87B & 87C and
Tripping Relay 86
operated
Nangkor Substation Load transferred to 132/33kV Transformer-II
at 10:28 hrs
3 01.04.2018 18:26 01.04.2018 18:28 0:02 1.1132/33kV
Transformer-I
All 33kV & 11kV
FeedersTripped on fault
Directional E/F- 67N
and tripping relay 86
operated
Nangkor Substation
Load transferred to 132/33kV Transformer II
and 132/33kV Transformer I kept under
shutdown
4 05.04.2018 14:59 05.04.2018 15:21 0:22 -7.3 Main Grid All feeders Tripped on fault - Salakati substation Main Grid failed from Salakati substation
5 13.04.2018 10:32 13.04.2018 10:36 0:02 -6.04 Main Grid All feedersDue to Heavy Lightning
and Rainfall- Tintibi Substation Main Grid failed from Tintibi substation
6 13.04.2018 10:32 13.04.2018 10:44 0:12 49.39 Nangkor-Deothang Nangkor-Deothang lineDue to Heavy Lightning
and Rainfall
Distance Protection
relay operated
Nangkor-Deothang
line
132kV Deothang Feeder tripped at the instand
of Grid failure showing the fault at 8.292km
towards Deothang, zone 1, start phase ABCN,
fault resistance 9.231 ohms, IA-571 KA, IB-
603A, IC-1.555kA, VAN-4.571kV, VBN-
6.112kV, VCN-4.571kV.
7 25.04.2018 16:06 25.04.2018 16:15 0:09 25.3 Main Grid All FeedersDue to Heavy Lightning
and Rainfall- Rangia Substation
Main Grid failed from Rangia Substation and
main grid restored via Salakati Grid from
Tintibi substation
8 25.04.2018 16:20 25.04.2018 16:25 0:05 9.9 Main Grid All FeedersDue to Heavy Lightning
and Rainfall- Jigmeling substation Main Grid failed from Jigmeling substation
132/33/11kV, Deothang substation
Sl. NoDate of
Tripping
Time of
Outage
(Hrs)
Date of
Normalizati
on
Time of Fault
cleared (Hrs)
Duration of
Outages
Load before
Outage
(MW)
Name of Feeders
Tripped
Name of Substations/Line
affected by faultReason of Fault
Relay indication and
operation
Exact location of fault
(Line
segment/substation)
Remarks
1 1.4.2018 10:23 1.4.2018 19:30 9:07 26.14132 kV I/C
NangkorDeothang S/S
Disc blast at s/s of I /C
Nangkhor feeder. NA Deothang SS
Feeder got tripped due to disc blast of incomer
Nangkhor feeder on B phase jumpering.
2 1.4.2018 10:23 1.4.2018 11:00 0:37 24.44 132kV Motonga Deothang S/SDisc blast at s/s of I /C
Nangkhor. Distance relay Deothang SS
The feeder got tripped due to disc blast of
incomer Nangkhor feeder on B phase
jumpering. Fault value: I1=273.82A,22.54deg,
I2=147.62A,7.77deg, I3=1212.75A,-155deg,
I4=798.30A,-151.64deg.
3 4.4.2018 16:25 4.4.2018 16:27 0:02 1.74132kV Transformer
IIDeothang S/S Tripped on fault
51A and 51C realy at
LV side operated.Deothang SS
Tripped due to transient fault.Charged and
found ok.
4 5.04.2018 14:58 5.04.2018 15:20 0:22 20.92132 kV Nangkhor
IncomerDeothang S/S Tripped on fault Nill Salakati substation Main Grid failed from Salakati substation
5 13.4.2018 22:31 13.4.2018 22:43 0:12 48.96132 kV Nangkhor
Incomer
132 kV Incomer
NangkhorTripped on fault Nill Nangkhor end
Grid fail from Nangkhor substation, at our end
breaker satatus was normal, but at there end
breaker was open
6 13.4.2018 22:31 13.4.2018 22:48 0:17 46.87 132kV Motonga 132kV Motonga Tripped on fault Distance relay Motonga
Feeder got tripped due to Nangkhor feeder
was tripped at there end. , Fault dist-
13.273Km, Fault loop- L1-L2. Fault value
I1=1365.66A,86.30deg, I2=1416.67A,-
38.03deg, I3=1257.27A, -155.74deg,
I4=61.73A, -26.57deg.
7 14.4.2018 18:44 14.4.2018 18:47 0:03 2.38 5 MVA Tr. IIAll 33kV & 11kV
outgoingssTree fall on line O/C Borbila, Nawkilo
Isolated the S/J fault feeder and charged the
Transformer.
8 23.4.2018 9:15 23.4.2018 9:18 0:03 1.78 5MVA Tr.IIAll 33KV & 11KV
outgoingsTripped on fault NA 33kV S/J feeder
The 5MVA Transformer II was tripped due to
33kV S/Jonkhar feeder tripped on over
9 25.4.2018 16:03 25.4.2018 16:10 0:07 21.38132 kV Nangkhor
IncomerAll
Due to bad weather all
feeders were affected.NA Motanga
Grid failed due to the Motanga-Rangia
feeder was tripped on O/C and E/F.
10 25.4.2018 16:15 25.4.2018 16:18 0:03 21.38132 kV Nangkhor
IncomerAll Tripped on fault NA
Jigmeling and Tintibi
substation
Grid failed due to the Jigmeling and Tingtibi
substation was tripped, as inform by
Transmission System Performance Report Second Quarterly Report-2018
27 | P a g e
132/33/11kV, Nganglam substation
Sl. NoDate of
Tripping
Time of
Outage
(Hrs)
Date of
Normalizati
on
Time of Fault
cleared (Hrs)
Duration of
Outages
Load before
Outage
(MW)
Name of Feeders
Tripped
Name of Substations/Line
affected by faultReason of Fault
Relay indication and
operation
Exact location of fault
(Line
segment/substation)
Remarks
1 1/4/2018 10:26 1/4/2018 10:39 0:13 6.01 132kV Nangkor All Tripped on fault O/C & 86 optd Nganglam end Feeder tripped due to bad weather condition.
2 7/4/2018 21:10 7/4/2018 21:12 0:02 17 DCCL DCCLHP Motor Problam at
DCCLO/C & 86 optd DCCL
Fdr. Charged after gatting information from
DCCL
3 7/4/2018 21:30 7/4/2018 21:45 0:15 17 DCCL DCCLHP Motor Problam at
DCCLO/C & 86 optd DCCL
Fdr. Charged after getting information from
DCCL
4 11/4/2018 5:25 11/4/2018 5:45 0:20 15.25 Tingtibi fdr Tingtibi line Tripped on fault O/C & 86 TingtibiShowing fault value IA-162A, IB-207A,IC--
636.4A)Fdr. Charged after getting information
5 13/4/2018 22:30 13/04/2018 22:34 0:04 1.53 Tingtibi fdr Tingtibi line Tripped on fault O/C & 86 -ABCN() N/khorShowing fault valueIA-834.1A,IB-870.2A,IC-
=917.8ADistance Relay optd (50.05 KMS)
6 25/4/2018 16:05 25/4/2018 16:24 0:19 16.45 Tingtibi fdr Tingtibi Line Tripped on fault Nil Tingtibi Grid failed from Tingtibi
7 27/4/2018 13:10 27/4/2018 13:14 0:04 24.22 Tingtibi fdr Tingtibi Line Tripped on faultDirection Earth fault
relay & 86 optd only.Tingtibi Transient fault
132kV, Motanga substation
Sl. NoDate of
Tripping
Time of
Outage
(Hrs)
Date of
Normalizati
on
Time of Fault
cleared (Hrs)
Duration of
Outages
Load before
Outage
(MW)
Name of Feeders
Tripped
Name of Substations/Line
affected by faultReason of Fault
Relay indication and
operation
Exact location of fault
(Line
segment/substation)
Remarks
1 1/4/2018 10:24 1/4/2018 11:03 0:39 24.9 All All Tripped on fault _ Deothang Ss The feeder got tripped due to disc blast of
2 2/4/2018 13:25 2/4/2018 13:34 0:09 0 Rangia feeder Motanga ss Tripped on fault _ Rangia Feeder tripped due to bad weather condition.
3 5/4/2018 14:59 5/4/2018 15:20 0:21 18 All fdrs All Tripped on fault _ _ Grid failed from both sources.
4 13/4/2018 22:30 13/4/2018 22:48 0:18 46.8 All fdrs All Tripped on fault _ _ Grid restore from Salakati.
5 13/4/2018 22:30 13/4/2018 23:50 1:20 33.4 Rangia feeder Motanga ss Tripped on fault Distance prot. Rangia R,Y,B phase operated at distance relay at our
6 25/4/2018 4:06 25/4/2018 11:26 7:20 4.3 Rangia fdr _ Tripped on fault OC & EF RangiaDue to line voltage level differents for Rangia
and incomer Deothang NLDC has not given
220/66/33kV, Dhajay substation
Sl. NoDate of
Tripping
Time of
Outage
(Hrs)
Date of
Normalization
Time of Fault
cleared (Hrs)
Duration of
Outages
Load before
Outage
(MW)
Name of Feeders
Tripped
Name of
Substations/Line
affected by fault
Reason of Fault Relay indication and operation
Exact location of fault
(Line
segment/substation)
Remarks
1 10.04.2018 15:50hrs 10.04.2018 16:05hrs 0:15 -34.400220kV Tsirang-
Jigmeling Line
Tsirang - Jighmeling
Line
The Line Tripped with
OC at R& Bphase with
the 1.87 & 2.00kA
Distance relay Main-I and Main-II Operated with OC atR&
Bphase at the distance of 22.3km to wards Jigmeling
(Z1/Z1B)
22.3km away from
Dhajay substation
2 25.04.2018 15:02hrs 25.04.2018 15:14hrs 0:12 -9.000220kV Tsirang-
Jigmeling Line
Tsirang - Jighmeling
Line
The Line Tripped with
OC at Bphase with the
1.51kA
Distance relay Main-I and Main-II Operated with OC at
Bphase at the distance of 19.2km to wards Jigmeling
(Z1/Z1B)
19.2km away from
Dhajay substation
132/66/33/11kV, Gelephu substation
Sl. NoDate of
Tripping
Time of
Outage
(Hrs)
Date of
Normalization
Time of Fault
cleared (Hrs)
Duration of
Outages
Load before
Outage
(MW)
Name of Feeders
Tripped
Name of
Substations/Line
affected by fault
Reason of Fault Relay indication and operation
Exact location of fault
(Line
segment/substation)
Remarks
1 05.04.2018 15.02hrs 05.04.2018 15.20hrs 0:18 -86.2 132 kv Gelephu-Salakati Line segmentOvercurrent on R&Y
phases
General trip,o/c on R & Y-Phase,zone I,Dist 41.16km
towards Salakati end,dis protection,3-phase,REL 670.
41.16km away from
Gelephu ss
2 14.04.2018 04.40hrs. 14.04.2018 05.01hrs 0:21 -7.8 132kv Gelephu-Salakati Line segmentOvercurrent on B&Y
phases
General trip,o/c on Y&B Phases, Zone I, Dist: 34.18km
towards Salakati end.
34.18km away from
Gelephu ss
132/33/11kV, Tingtibi substation
Sl. NoDate of
Tripping
Time of
Outage
(Hrs)
Date of
Normalization
Time of Fault
cleared (Hrs)
Duration of
Outages
Load before
Outage
(MW)
Name of Feeders
Tripped
Name of
Substations/Line
affected by fault
Reason of Fault Relay indication and operation
Exact location of fault
(Line
segment/substation)
Remarks
1 3/4/2018 13:12 Hrs 3/4/2018 13:30 Hrs 0:18 20.880132kV Tingtibi-
Nanglam feeder
Tingtibi Substation
/132kV Tingtibi-
Nanglam Line
Earth fault
86 &(distance relay data) : Start phase BNC,Fault
duration:1.669ms,Fault zone :None, System Frequency
:49.94HZ.
132kV Tingtibi-
Nanglam feeder Line
2 3/4/2018 13:12 Hrs 3/4/2018 13:37 Hrs 0:25 5.920132kV Tingtibi-
Yourmoo feeder
Tingtibi Substation
&132kV Tingtibi-
Yourmoo Line
Overcurrent on three
phases
51N,50C &(Distance relay ) :Active Group-1,Trip zone-
1,Start phase:BC,Trip-ABC,System
frequency:49.94HZ,Fault Duration:15.02ms,Relay trip
time:80.1ms,Fault location:14.68KM,IA-25.95A,IB-26.16A,IC-
129.27A,VAN-77.25V,VBN-76.85V,VCN-75.79V,Fault
resistance XY:3.829 ohms.
132kV Tingtibi-
Yourmoo feeder Line
3 3/4/2018 13:12 Hrs 3/4/2018 13:42 Hrs 0:30 -27.640132kV Tingtibi-
Jigmeling feeder
Tingtibi Substation
/132kV Tingtibi-
Jigmeling Line
Earth fault
51N,50C ,86 & (Distance relay data) :Active Group-I,Start
phase:BCN,Fault duration:1.669ms,Fault zone :None,
System Frequency :49.94HZ
132kV Tingtibi-
Jigmeling feeder Line
4 5/4/2018 15:00 Hrs 5/4/2018 15:24 Hrs 0:24 -68.000132kV Tingtibi-
Jigmeling feeder
Tingtibi Substation
/132kV Tingtibi-
Jigmeling Line
Only non directional
over current relay
operated , breaker did
not triped at Tingtibi
substation.
51A,51C & 86132kV Tingtibi-
Jigmeling feeder Line
5 5/4/2018 15:00 Hrs 5/4/2018 15:24 Hrs 0:24 60.000132kV Tingtibi-
Nanglam feeder
Tingtibi Substation
/132kV Tingtibi-
Nanglam Line
Only non directional
over current relay
operated , breaker did
not triped at Tingtibi
substation.
51A,51C & 86132kV Tingtibi-
Nangalm feeder Line
6 10/4/2018 15:50 Hrs 10/4/2018 15:59 Hrs 0:09 -32.940132kV Tingtibi-
Jigmeling feeder
Tingtibi Substation
/132kV Tingtibi-
Jigmeling Line
Overcurrent
(Distance relay ) :Active Group-1,Trip zone-none ,System
frequency:50.02 HZ,Fault Duration:43.32 ms,IA-595.6A,IB-
163.9A,IC-550.8A,VAN-28.17kV,VBN-69.24kV,VCN-26.57kV.
132kV Tingtibi-
Jigmeling feeder Line
7 11/4/2018 05:32 Hrs 11/4/2018 05:39 Hrs 0:07 17.230132kV Tingtibi-
Nanglam feeder
Tingtibi Substation
/132kV Tingtibi-
Nanglam Line
Overcurrent
86 & (Distance relay ) :Active Group-1,Trip zone-2 ,System
frequency:49.93HZ,Fault Duration:78.44 ms,IA-891.8A,IB-
141.4A,IC-1012A,VAN-37.48kV,VBN-79.89kV,VCN-
35.96kV.Fault location:78.12KM.
78.12km towards
Ngalam ss
8 13/4/2018 22:31 Hrs 13/4/2018 22:40 Hrs 0:11 19.150132kV Tingtibi-
Nanglam feeder
Tingtibi Substation
/132kV Tingtibi-
Nanglam Line
Overcurrent
86 & (Distance relay ) :Active Group-1,Trip zone-none
,System frequency:49.97HZ,Fault Duration:35.02 ms,IA-
551.3A,IB-531.3A,IC-686.9A,VAN-50.93kV,VBN-
58.83kV,VCN-53.21kV
132kV Tingtibi-
Nangalm feeder Line
9 25/4/2018 14:55 Hrs 25/4/2018 15:11 Hrs 0:16 21.450132kV Tingtibi-
Jigmeling feeder
Tingtibi Substation
&132kV Tingtibi-
Jigmeling Line
Overcurrent on all three
phases
86 & (Distance relay ) :RYB phase trip,Trip zone-1 ,System
frequency:49.86 HZ,Realy trip tme:81.89 ms,Fault
location:38.53KM,IA-725.1A,IB-131.3A,IC-776.4A,VAN-
19.77kV,VBN-81.35kV,VCN-16.75kV.Fault
resistance:794.4Mohms.
132kV Tingtibi-
Jigmeling feeder Line
10 25/4/2018 15:28 Hrs 25/4/2018 16:10 Hrs 0:42 21.450132kV Tingtibi-
Jigmeling feeder
Tingtibi Substation
&132kV Tingtibi-
Jigmeling Line
Overcurrent on all three
phases
86 & (Distance relay ) :RYB phase trip,Trip zone-1 ,System
frequency:49.82 HZ,Realy trip tme:80.11 ms,Fault location
XY:40.89KM,IA-726.8A,IB-96.34A,IC-713.8A,VAN-
20.03kV,VBN-81.59kV,VCN-16.57kV.Fault
resistanceXY:481.7Mohm zone-1.
132kV Tingtibi-
Jigmeling feeder Line
11 25/4/2018 16:18 Hrs 25/4/2018 16:20 Hrs 0:02 21.450132kV Tingtibi-
Jigmeling feeder
Tingtibi Substation
&132kV Tingtibi-
Jigmeling Line
Overcurrent
86 & (Distance relay ) : Start Phase :CAN,ABC trip,Trip
zone-none ,System frequency:49.96 HZ,IA-25.40A,IB-
32.21A,IC-56.36A,VAN-2.922kV,VBN-1.512kV,VCN-2.497kV.
132kV Tingtibi-
Jigmeling feeder Line
132/33kV, Yurmoo substation
Sl. NoDate of
Tripping
Time of
Outage
(Hrs)
Date of
Normalization
Time of Fault
cleared (Hrs)
Duration of
Outages
Load before
Outage
(MW)
Name of Feeders
Tripped
Name of
Substations/Line
affected by fault
Reason of Fault Relay indication and operation
Exact location of fault
(Line
segment/substation)
Remarks
1 03.04.2018 13:10HRS 03.04.2018 13:35HRS 0:25 5.6 132kV Tingtibi I/C 132/33kV Yurmoo SS Transient fault Nill 14.6km
2 05.04.2018 15:00HRS 05.04.2018 15:20HRS 0:20 5.3 132kV Tingtibi I/C 132/33kV Yurmoo SS Grid fail from Salakita Nill Salakita
Transmission System Performance Report Second Quarterly Report-2018
28 | P a g e
220/132/33kV, Jigmeling substation
Sl. NoDate of
Tripping
Time of
Outage
(Hrs)
Date of
Normalization
Time of Fault
cleared (Hrs)
Duration of
Outages
Load before
Outage
(MW)
Name of Feeders
Tripped
Name of
Substations/Line
affected by fault
Reason of Fault Relay indication and operation
Exact location of fault
(Line
segment/substation)
Remarks
1 10.04.2018 15:49 10.04.2018 18:33 2:44 35.58 220kV Tsirang Jigmeling - Tsirang lineOvercurrent on R&B
phases
Main1 main 2 optd. R & B phase trip. General relay trip.
86.1 &86.2 operated. Zone 1 trip.Main1:14.7km
2 25.04.2018 14:54 25.04.2018 15:10 0:16 -26.11 132kV Tingtibi JigmelingOvercurrent on R&B
phasesMain1 & main 2 optd. R & B phae trip.Zone 1 trip.
Main1: 19.5 km Main
II: 18.7km
3 25.04.2018 15:02 25.04.2018 15:21 0:19 11.21 220kV Tsirang JigmelingOvercurrent on B
phaseMain1 & main 2 optd. B phae trip. Zone 1 trip.
Main1: 15.7km Main2:
14.14km
4 25.04.2018 15:27 25.04.2018 16:08 0:41 11.21 132Tingtibi JigmelingOvercurrent on R&B
phasesMain1 & main2 optd. R & B phase trip. Zone1 trip.
Main1: 18.1km Main2
: 18.9km
5 25.04.2018 15:40 25.04.2018 15:45 0:05 4.1 132 kV Gelephu JigmelingOvercurrent on all three
phasesMain1 & main2 optd, R,Y and B phase trip. Zone 2 trip.
Main1: 13.55km
main2: 21.5km
Grid available from
Tintibi & Gelephu
6 25.04.2018 16:17 25.04.2018 16.23 0:06 -10.11 132kV Tingtibi JigmelingOvercurrent on all three
phasesMain1 & main 2 optd. R,Y and B phase trip.
Main1: 19.8km main2:
21.5km
Grid available from
Tintibi & Gelephu
7 27.04.2018 8:50 27.04.2018 9:00 0:10 16.2 220kV Tsirang Jigmeling Overcurrent Main2 optd. General relay trip.
8 27.04.2018 13:07 27.04.2018 13:15 0:08
HV: ICT1 -
0.661, ICT2 -
0.838.
ICT 1 & 2, both HV JigmelingOvercurrent and
Earthfault
64/51 NS LV trip, LV SEF trip, main relay trip. 86.1 and 86.2
optd on both ICT 1 & 2 on HV. Jigmeling substation
May, 2018
132/33/11kV, Kilikhar substation
Sl. NoDate of
Tripping
Time of
Outage
(Hrs)
Date of
Normalizati
on
Time of Fault
cleared (Hrs)
Duration of
Outages
Load before
Outage
(MW)
Name of Feeders
Tripped
Name of Substations/Line
affected by faultReason of Fault
Relay indication and
operation
Exact location of fault
(Line
segment/substation)
Remarks
1 04.05.2018 12:01 04.05.2018 12:15 0:14 3.880 132kV I/C All Tripped on fault Nill Kurichu
2 05.05.2018 12:59 05.05.2018 13:00 0:01 3.880 132kV I/C All Tripped on fault Nill Kurichu
3 05.05.2018 13:08 05.05.2018 13:10 0:02 3.670 132kV I/C All Tripped on fault Nill Kurichu
132/33/11kV, Kanglung substation
Sl. NoDate of
Tripping
Time of
Outage
(Hrs)
Date of
Normalizati
on
Time of Fault
cleared (Hrs)
Duration of
Outages
Load before
Outage
(MW)
Name of Feeders
Tripped
Name of Substations/Line
affected by faultReason of Fault
Relay indication and
operation
Exact location of fault
(Line
segment/substation)
Remarks
1 4/5/2018 12:10 4/5/2018 12:15 0:05 2.12 132kV Incomer All NATripping Relay - 86
operated at Kurichu endKurichu
132/33/11kV, Nangkhor substation
Sl. NoDate of
Tripping
Time of
Outage
(Hrs)
Date of
Normalizati
on
Time of Fault
cleared (Hrs)
Duration of
Outages
Load before
Outage
(MW)
Name of Feeders
Tripped
Name of Substations/Line
affected by faultReason of Fault
Relay indication and
operation
Exact location of fault
(Line
segment/substation)
Remarks
1 09.05.2018 19:13 hrs 09.05.2018 19:18 hrs 0:05 1.92132/33kV Transformer-
I (HV)All 33kV & 11kV feeders Tripped on fault
Directional E/F-67N &
tripping relay 86 operatedNangkor substation
Transformer tripped
due to transient fault.
2 10.05.2018 16:58 hrs 10.05.2018 17:05 hrs 0:07 0.81132/33kV Transformer-
I (HV)All 33kV & 11kV feeders Tripped on fault
Differential relay-87C &
tripping relay 86 operated.Nangkor substation
Test charged at 17:00
hrs but tripped with
Differential relay-87B,
87C & tripping relay 86
operated.
132/33/11kV, Deothang substation
Sl. NoDate of
Tripping
Time of
Outage
(Hrs)
Date of
Normalizati
on
Time of Fault
cleared (Hrs)
Duration of
Outages
Load before
Outage
(MW)
Name of Feeders
Tripped
Name of Substations/Line
affected by faultReason of Fault
Relay indication and
operation
Exact location of fault
(Line
segment/substation)
Remarks
1 31.5.2018 8:56 31.5.2018 9:01 0:05 0:28132/33kV 5 MVA
Transformer IDeothang S/S Tripped on fault Tripping relay 86 unknown
Transformer got
tripped by the 33kV
Gomder feeder
132/33/11kV, Nganglam substation
Sl. NoDate of
Tripping
Time of
Outage
(Hrs)
Date of
Normalizati
on
Time of Fault
cleared (Hrs)
Duration of
Outages
Load before
Outage
(MW)
Name of Feeders
Tripped
Name of Substations/Line
affected by faultReason of Fault
Relay indication and
operation
Exact location of fault
(Line
segment/substation)
Remarks
1 31.5.2018 22:02 31.5.2018 22:16 0:14 14.67 132kV Tingtibi NilTripped due to bad
weatherE/F & 86 optd
6.171mi towards
Tingtibi
Tripped on E/F, ABCN,
Distance-6.171mi, IA-
1.524KA,IB-1.642KA,IC-
1.457KA,Fdr
132kV, Motanga substation
Sl. NoDate of
Tripping
Time of
Outage
(Hrs)
Date of
Normalizati
on
Time of Fault
cleared (Hrs)
Duration of
Outages
Load before
Outage
(MW)
Name of Feeders
Tripped
Name of Substations/Line
affected by faultReason of Fault
Relay indication and
operation
Exact location of fault
(Line
segment/substation)
Remarks
No Tripping
220/66/33kV, Dhajay substation
Sl. NoDate of
Tripping
Time of
Outage
(Hrs)
Date of
Normalization
Time of Fault
cleared (Hrs)
Duration of
Outages
Load before
Outage
(MW)
Name of Feeders
Tripped
Name of
Substations/Line
affected by fault
Reason of FaultRelay indication and
operation
Exact location of fault
(Line
segment/substation)
Remarks
1 27.05.2018 04:12hrs 27.05.2018 04:26hrs 0:14 -22.7220kV Tsirang-
JigmelingTsi-Jig Line O/C at R &Y Phase 21, Z1/Z1B, 17.4KM Linesegnment
132/66/33/11kV, Gelephu substation
Sl. NoDate of
Tripping
Time of
Outage
(Hrs)
Date of
Normalization
Time of Fault
cleared (Hrs)
Duration of
Outages
Load before
Outage
(MW)
Name of Feeders
Tripped
Name of
Substations/Line
affected by fault
Reason of FaultRelay indication and
operation
Exact location of fault
(Line
segment/substation)
Remarks
1 08.05.2018 16.40hrs 08.05.2018 17.20hrs 0:40 6 131 kv Gelephu-Salakati Salakati Bad weather
General trip,o/c on Y-
Phase, Zone II, Dist
41.84km towards
Salakati end
SalakatiHeavy rain & thunder,
lightning
2 25.05.2018 01.27hrs 25.05.2018 01.55hrs 0:38 22 132 kv Gelephu-Salakati Salakati Bad weather
General trip,o/c on 3 -
Phases, Zone I, Dist
39.67km towards
Salakati end
SalakatiHeavy rain & thunder,
lightning
3 28.05.2018 20.44hrs 28.05.2018 21.07hrs 0:23 9 133 kv Gelephu-Salakati Salakati Bad weather
General trip,o/c on B-
Phase, Zone I, Dist
27km towards Salakati
end
SalakatiHeavy rain & thunder,
lightning
Transmission System Performance Report Second Quarterly Report-2018
29 | P a g e
June, 2018
132/33/11kV, Kilikhar substation
Sl. No Date of Tripping
Time of
Outage
(Hrs)
Date of
Normalizati
on
Time of Fault
cleared (Hrs)
Duration of
Outages
Load before
Outage
(MW)
Name of Feeders
Tripped
Name of Substations/Line
affected by faultReason of Fault
Relay indication and
operation
Exact location of fault
(Line
segment/substation)
Remarks
1 06.06.18 5:30 06.06.18 5:34 0:04 5.650 I/C (kurichu) All the O/G Fdrs Tripped on Fault Nill KurichuTrip from Kurichu (relay 86 operated
at Kurichu end)
2 27.06.18 11.54 27.06.18 12 0:06 4.800 I/C (kurichu) All the O/G Fdrs Tripped on Fault Nill KurichuTrip from Kurichu (Distance relay
operated at Kurichu end)
3 29.06.18 17:16 29.06.18 17:19 1:03 4.060 I/C (kurichu) All the O/G Fdrs Tripped on Fault Nill KurichuTrip from Kurichu (relay 86 operated
at Kurichu end)
132/33/11kV, Kanglung substation
Sl. No Date of Tripping
Time of
Outage
(Hrs)
Date of
Normalizati
on
Time of Fault
cleared (Hrs)
Duration of
Outages
Load before
Outage
(MW)
Name of Feeders
Tripped
Name of Substations/Line
affected by faultReason of Fault
Relay indication and
operation
Exact location of fault
(Line
segment/substation)
Remarks
1 27.06.2018 11:55 27.06.2018 11:59 0:04 2.48 132kV incomer
Tripped while
shutdown Nangkhor
torwards Deothang
for emergency
Differential relay optd.
At Kuruchu.Kurichu Supply fail from Kurichu end
2 29/06/2018 17:14 29/06/2018 17:17 0:03 2.33 132kV incomer Tripped on faultTriped relay 86 optd.
At Kurichu.Kurichu Supply fail from Kurichu end
3 29/06/2018 21:22 29/06/2018 21:44 0:22 4.36 132kV incomer
Hand tripped on
emergency, during
conductor snapped
on Tsebar Feeder
NA Nangkhor
Hand tripped from Nangkhor
substation as the 5MVA transformer
didn’t tripped as and when the
conductor snapped on Tsebar feeder.
132/33/11kV, Nangkhor substation
Sl. No Date of Tripping
Time of
Outage
(Hrs)
Date of
Normalizati
on
Time of Fault
cleared (Hrs)
Duration of
Outages
Load before
Outage
(MW)
Name of Feeders
Tripped
Name of Substations/Line
affected by faultReason of Fault
Relay indication and
operation
Exact location of fault
(Line
segment/substation)
Remarks
132/33/11kV, Deothang substation
Sl. No Date of Tripping
Time of
Outage
(Hrs)
Date of
Normalizati
on
Time of Fault
cleared (Hrs)
Duration of
Outages
Load before
Outage
(MW)
Name of Feeders
Tripped
Name of Substations/Line
affected by faultReason of Fault
Relay indication and
operation
Exact location of fault
(Line
segment/substation)
Remarks
1 11.6.2018 10:35 11.6.2018 10:41 0:06 2.45132/33kV Transformer
II5MVATansformer II Due to 33KV S/J fdr. 86 relay operated
Prayer flag fall on 33kv
S/J line
Due to S/Jongkhar fdr.fault,5MVA
TX.2 got tripped.Only 86 relay
opperated on TX.2 side.Reset the
relay & charged withstand.
2 16.6.2018 21:59 16.6.2018 22:07 0:08 1.71132/33kV Transformer
II5MVATansformer II
Due to 33kV
S/jongkhar feeder.O/C Unknown
TRF. tripped due to fault at
S/jongkhar fdr.charged the tx after
isolating S/jongkhar fdr.
No Tripping
132/33/11kV, Nganglam substation
Sl. No Date of Tripping
Time of
Outage
(Hrs)
Date of
Normalizati
on
Time of Fault
cleared (Hrs)
Duration of
Outages
Load before
Outage
(MW)
Name of Feeders
Tripped
Name of Substations/Line
affected by faultReason of Fault
Relay indication and
operation
Exact location of fault
(Line
segment/substation)
Remarks
1 21.6.2018 4:32 21.6.2018 4:42 0:10 7.88 132kV Tingtibi Nganglam Due to heavy rainfall E/F 86 optd Tingtibi
Fault value IA-1.579A,IB-120.8A,IC-
1.52KA,Distance 5.157mi towards
Tingtibi.Fdr.Charged
132kV, Motanga substation
Sl. No Date of Tripping
Time of
Outage
(Hrs)
Date of
Normalizati
on
Time of Fault
cleared (Hrs)
Duration of
Outages
Load before
Outage
(MW)
Name of Feeders
Tripped
Name of Substations/Line
affected by faultReason of Fault
Relay indication and
operation
Exact location of fault
(Line
segment/substation)
Remarks
1 10/6/2018 19:13 10/6/2018 21:40 2:27 39.9 Rangia feeder Rangia feeder Direct trip received _ Rangia Ss
CT blust Rangia-Motanga line at
rangia end.
2 12/6/2018 15:04 12/6/2018 18:14 3:42 45.5 Rangia feeder Rangia feeder Emergency Trip _ Rangia Ss
33/11kV transfomer burnt & damage
at Rangia end.
220/132/33kV, Jigmeling substation
Sl. NoDate of
Tripping
Time of
Outage
(Hrs)
Date of
Normalization
Time of Fault
cleared (Hrs)
Duration of
Outages
Load before
Outage
(MW)
Name of Feeders
Tripped
Name of
Substations/Line
affected by fault
Reason of FaultRelay indication and
operation
Exact location of fault
(Line
segment/substation)
Remarks
1 6/4/2018 14:04 6/4/2018 14:46 0:42 35.15whole substation
blackout Jigmeling
2 6/13/2018 20:48 6/13/2018 21:00 0:12 30.57 132 kV Tingtibi line Jigmeling SS
86.1, 86.2 optd. Main 1
R,Y B optd. Main
2 R,Y,B optd
main 1= 18.2 km
main2 = 20.93kmTransient fault
3 6/13/2018 22:06 6/13/2018 22:13 0:07 22.13 132kV Tingtibi line Jigmeling SS
main 1 optd, RYB
phase tripped. Main
2 optd. RYB phase
tripped. 86.1 tripped
main1 = 20.7km main2
= 18.92kmTransient fault
4 6/17/2018 4:28 6/17/2018 4:36 0:08 9.96 132kV Tingtibi line Jigmeling SS
main1 optd, RYB phase
tripped main2 optd,
RYB phase tripped
Main1 =11.77km
main2 = 12kmTransient fault
5 6/26/2018 0:57 6/24/2018 1:09 0:12 11.51 132kV Tingtibi line Jigmeling SS
main1 optd, RYB phase
tripped main2 optd,
RYB phase tripped
Main1= 15.2km
Main2= 15.82kmTransient fault
220/66/33kV, Dhajay substation
Sl. NoDate of
Tripping
Time of
Outage
(Hrs)
Date of
Normalization
Time of Fault
cleared (Hrs)
Duration of
Outages
Load before
Outage
(MW)
Name of Feeders
Tripped
Name of
Substations/Line
affected by fault
Reason of FaultRelay indication and
operation
Exact location of fault
(Line
segment/substation)
Remarks
1 04.06.2018 14:05hrs 04.06.2018 14:40hrs 0:00 -35.1220kV Tsirang-
JigmelingTsi-Jig Line Grid Fail
21 operated, , 17.4km
Z1/Z1BLinesegnment
2 04.06.2018 14:05hrs 04.06.2018 14:45hrs 0:00 15.9 220kv Tsirang-DHPC Tsi-DHPC Grid Fail21 operated, , 23.2km
Z1/Z1BLinesegnment
Transmission System Performance Report Second Quarterly Report-2018
30 | P a g e
132/66/33/11kV, Gelephu substation
Sl. NoDate of
Tripping
Time of
Outage
(Hrs)
Date of
Normalization
Time of Fault
cleared (Hrs)
Duration of
Outages
Load before
Outage
(MW)
Name of Feeders
Tripped
Name of
Substations/Line
affected by fault
Reason of FaultRelay indication and
operation
Exact location of fault
(Line
segment/substation)
Remarks
1 04.06.2018 14.05 04.06.2018 19.44 5:39 8.2 Salakati & Jigmeling Gelephu substation Overloading. Non Unkown
whole Grid fail at
14.05hrs but breaker
did not triped at our
end.
2 13.06.2018 21.55 13.06.2018 22.30 0:35 31.8 Salakati non Bad weather
General Trip,R-ph,Zone-
1,dist:14.99km towards
salakati.
salakati lineThunder lightening &
heavy rainfall.
132/33/11kV, Tingtibi substation
Sl. NoDate of
Tripping
Time of
Outage
(Hrs)
Date of
Normalization
Time of Fault
cleared (Hrs)
Duration of
Outages
Load before
Outage
(MW)
Name of Feeders
Tripped
Name of
Substations/Line
affected by fault
Reason of FaultRelay indication and
operation
Exact location of fault
(Line
segment/substation)
Remarks
1 4/6/2018 14:03Hrs 4/6/2018 14:50 Hrs 0:47 21.920132kV Tingtibi-
Jigmeling feeder
132kV Tingtibi-
Jigmeling LineTempoary Fault
(Distance relay ) :Trip
Phase:ABC,Over
Voltage,Fault
Duration:3.011ms,Relay
trip
time:80.02ms,System
Frequency:55.35 HZ,IA-
18.92,IB-18.95 A,IC-
20.23A,VAN-
83.76KV,VBN-
84.61KV,VCN-85.41kV.
132kV Tingtibi-
Jigmeling feeder Line
2 4/6/2018 14:03 Hrs 4/6/2018 14:50 Hrs 0;47 18.680132kV Tingtibi-
Nanglam feeder
132kV Tingtibi-
Nanglam LineTempoary Fault
(Distance relay ) :Trip
Phase-ABC, Over
Voltage,Fault
Duration:6.023ms,Relay
trip
time:80.85ms,System
Frequency:55.43 HZ,IA-
00,IB-00A,IC-00A,VAN-
82.82KV,VBN-
85.61KV,VCN-85.39kV.
132kV Tingtibi-
Nanglam feeder Line
3 4/6/2018 14:03 Hrs 4/6/2018 15:30 Hrs 1:27 3.200132kV Tingtibi-
Yourmoo feeder
132kV Tingtibi-
Yourmoo LineTempoary Fault
(Distance relay ) :Trip-
ABC,Fault
Duration:3.011ms,Relay
trip
time:81.04ms,System
Frequency:53.35HZ,IA-
14.63A,IB-13.70A,IC-
15.6A,VAN-
83.82KV,VBN-
85.62KV,VCN-85.040kV.
132kV Tingtibi-
Yourmoo feeder Line
During The charging of
132kV Tingtibi-
Yourmoo feeder the
breaker did not stood
normal due to Pole
discripency and we had
charged the 132kV
Tingtibi-Yourmoo Line
Through 132 kV
Transfer bus.
5 13/6/2018 20:50Hrs 13/6/2018 20:58 Hrs 0;08 30.600132kV Tingtibi-
Jigmeling feeder
132kV Tingtibi-
Jigmeling LineTempoary Fault
(Distance relay ) :Trip
Phase:ABC,Trip Zone-
I, Fault
Location:35.89KM,Faul
t Duration:73.5ms,Fault
Resistance:1.5720
ohms,Relay trip
time:80.18ms,System
Frequency:49.89 HZ,IA-
805.4,IB-830.9A,IC-
824.4A,VAN-
12.46KV,VBN-
12.87KV,VCN-11.38kV.
132kV Tingtibi-
Jigmeling feeder Line
6 13/6/2018 22:06Hrs 13/6/2018 22:13 Hrs 0;07 30.560132kV Tingtibi-
Jigmeling feeder
132kV Tingtibi-
Jigmeling LineTempoary Fault
(Distance relay )
:Active Group-I,Start
Phase:ABCN,Trip
Phase:ABC,Trip Zone-
I, Fault
Location:37.43KM,Faul
t
Duration:78.51ms,Relay
trip
time:80.18ms,System
Frequency:49.89 HZ,IA-
827A,IB-828.5A,IC-
822.1A,VAN-
13.51KV,VBN-
14.33KV,VCN-13.23kV.
132kV Tingtibi-
Jigmeling feeder Line
7 17/6/2018 04:30 Hrs 17/6/2018 4:37 Hrs 0:07 17.500132kV Tingtibi-
Jigmeling feeder
132kV Tingtibi-
Jigmeling LineTempoary Fault
(Distance relay )
:Active Group-1,Trip
zone-II,Started
Phase:ABCN,Fault
Duration:88.30ms,Syste
m
Frequency:50.02HZ,Tri
p phase:ABC,Fault
Alarm:None,Fault
Location:44.58KM,Faul
t
Resistance:922.8Mohm
s,IA-773.8A,IB-
804.5A,IC-788.6A,VAN-
16.04kV,VBN-
12.09kV,VCN-14.67kV.
132kV Tingtibi-
Jigmeling feeder Line
8 21/6/2018 04:32 Hrs 21/6/2018 04:45 Hrs 0;13 6.180132kV Tingtibi-
Nanglam feeder
132kV Tingtibi-
Nanglam LineTempoary Fault
(Distance relay )
:Active Group-I,Start
Fault Phase:ABCN,Trip
Zone-II, Fault
Location:81.59KM,Faul
t
Duration:84.98ms,Relay
trip time:00ms,System
Frequency:50.01HZ,IA-
931.6A,IB-116.3A,IC-
1.066KA,VAN-
38.13KV,VBN-
78.85KV,VCN-37.37kV.
132kV Tingtibi-
Nanglam feeder Line
9 24/6/2018 00:56 Hrs 24/6/2018 01:07 Hrs 0:11 12.700132kV Tingtibi-
Jigmeling feeder
132kV Tingtibi-
Jigmeling LineTempoary Fault
(Distance relay ) :Trip
Phase-ABC,Start
Phase:ABCN,Trip
Phase:ABC,Trip Zone-
I, Fault
Location:37.59KM,Faul
t
Duration:78.74ms,Relay
trip
time:80.14ms,System
Frequency:49.92
HZ,Fault
resistance:1.693
ohms,IA-755.2A,IB-
793A,IC-787A,VAN-
13.37KV,VBN-
12.66KV,VCN-11.95kV.
132kV Tingtibi-
Jigmeling feeder Line
132/33kV, Yurmoo substation
Sl. NoDate of
Tripping
Time of
Outage
(Hrs)
Date of
Normalization
Time of Fault
cleared (Hrs)
Duration of
Outages
Load before
Outage
(MW)
Name of Feeders
Tripped
Name of
Substations/Line
affected by fault
Reason of FaultRelay indication and
operation
Exact location of fault
(Line
segment/substation)
Remarks
No tripping
Transmission System Performance Report Second Quarterly Report-2018
31 | P a g e
Annexure-VI
Western grid Outages
April, 2018
400/220/66/11kV Malbase substation
Sl. NoDate of
Tripping
Time of
Outage
Date of
Normalization
Time of
Fault
cleared
Duration of
Outages
Load before
Outage
(MW)
Name of
Feeders/Equipment
Tripped
Name of
Substations/Line
affected by fault
Reason of Fault Relay indication and operation
Exact location of fault
(Line
segment/substation)
Remarks
1 12.04.2018 15:15 12.04.2018 15:29 0:14 -35220kV Malbase -
Chukha
22okV Malbase -
Chukha
Tripped due to
trasient fault
TRIP-R-PH,TRIP-Y- PH,TRIP-B-
PH,START-R-PH,START-NUE, ZONE I
TRIP, CARR-SEND. Trip Values:
I1=5740A<283.7deg,
I2=120.2A<300.7deg,
I3=198.3A<275.4deg,
I4=6067A<283.0deg
Fault loop LI-N, Distance
= 2.5km
2 12.04.2018 15:15 12.04.2018 15:36 0:21 38 66kV Pasakha Feeder - I66kV Pasakha Feeder -
I
Tripped due to
trasient fault
51-start,86optd,GENERAL TRIP,IEF-
50N-TRIP TripValues:
I1=406.26A<44.99deg,
I2=32.15A<147.11deg,
I3=2185.81A<64.90deg,
I4=2571.96A<-117.45deg
Line
3 12.04.2018 15:15 12.04.2018 15:35 0:20 3866kV Pasakha Feeder -
II
66kV Pasakha Feeder -
II
Tripped due to
trasient fault
51-start,86optd,GENERAL TRIP,IEF-
50N-TRIP Trip Values:
I1=360.67A<31.33deg,
I2=37.76A<-87deg,
I3=1969.46A<66.08deg,
I4=360.67A<31.33deg
Line
4 12.04.2018 15:15 12.04.2018 15:34 0:19 4366kV Pasakha Feeder -
IV
66kV Pasakha Feeder -
IV
Tripped due to
trasient fault
51-start,86optd,GENERAL TRIP,IEF-
50N-TRIP I1=417.65A<66.28deg,
I2=504.91A<-108.59deg,
I3=138.39A<-170.82deg,
I4=417.65A<-66.28deg
Line
5 17.04.2018 20:45 17.04.2018 21:41 0:56 19220kV Malbase -
Samtse Feeder.
220kV Malbase -
Samtse Feeder.Trip
START-R-PH,M1 TRIP,TRIP-R-
PH,TRIP-Y-PH,TRIP-B-PH,START-
NUE, ZONE I START, ZONE-2-
START,ZONE-3-START,M1 SEND,B/U
TRIP,R-PH CB-OPEN,Y-PH CB OPEN,B-
PH CB OPEN,M1/BC START,AR
Trip Values:
I1=7758A<289.4deg,
I2=7375A<165.6deg,
I3=113.8A<66.4deg,
I4=6008A<222.8deg
Line
6 17.04.2018 20:45 17.04.2018 21:27 0:42 4150/63MVA Trasformer -
III
50/63MVA Trasformer -
III Trip
OLTC BUCH TRIP
Trip Values:
I1=107.48A<69.73deg,
I2=79.48A<31.78deg,
I3=184.84A<99.18deg,
I4=333.77A<76.96deg
Substation
7 17.04.2018 21:11 17.04.2018 21:34 0:23 80 200 MVA ICT 200 MVA ICTTripped due to
trasient fault
51-start,86optd,GENERAL TRIP,IEF-
50N-TRIP Trip Values:
HV L1=0.056A<27deg,
HV L2=0.065A<-95.74deg,
HV L3=.110A<-109.7deg,
LV L1=0.098A<160.2deg,
LV L2=0.082A<68.80deg,
LV L3=0.076A<66.15deg,
L1 CURRENT TIE=0.025A<-173.8deg
Substation
8 17.04.2018 21:11 17.04.2018 21:48 0:37 69400kV Malbase -
Siliguri Feeder.
400kV Malbase -
Siliguri Feeder.Trip
51-start,86optd,GENERAL TRIP,IEF-
50N-TRIP Trip Values:
I1=2789A<95.50deg
I2=240.3A<293.3deg
I3=414.4A<263.4deg
I4=4302A<96.19deg
Line
9 21.04.2018 19:24 21.04.2018 19:35 0:11 18220kV Malbase -
Samtse Feeder.
220kV Malbase -
Samtse Feeder.
Tripped due to
trasient fault
M-1trip,TripR,Y&B phase,zone1.2&3
Trip,carrier fail
Trip Values:
IL1=188.5A<306.6deg.
IL2=4675A<173.3deg.
IL3=4392A<32.12deg.
IL4=2752A<104.2deg.
Fault loop = L2-L3 at a
distance of 29.3 km.Transient Fault.
10 25.04.2018 13:56 25.04.2018 16:30 2:34 3866kV Pasakha Feeder -
IV
66kV Pasakha Feeder -
IVTrip
86 optd, General Trip, 50N Trip
Trip Values:
IL1=588.52A<-7.4deg.
IL2=2820.97A<-168.68deg.
IL3=2581.63A<54.66deg.
Line
11 25.04.2018 13:56 25.04.2018 16:31 2:35 3366kV Pasakha Feeder -
II
66kV Pasakha Feeder -
IITrip
86 optd, General Trip, IOC-50 Trip, IEF
50N Trip Trip Values:
IL1=380.68A<-11.27deg.
IL2=3222.93A<-170.26deg.
IL3=2657.65A<48.69deg.
Line
12 25.04.2018 13:56 25.04.2018 16:32 2:36 33 66kV Pasakha Feeder - I66kV Pasakha Feeder -
ITrip
86 optd, General Trip, IEF-50N Trip
Trip Values:
IL1=245.28A<-9.08deg.
IL2=2640.23A<-133.59deg.
IL3=2225.01A<-81.37deg.
IL4=1266.24A<-11.05 deg
Line
220/66/11kV Singhigaon substation
Sl. NoDate of
Tripping
Time of
Outage
Date of
Normalization
Time of
Fault
cleared
Duration of
Outages
Load before
Outage
(MW)
Name of
Feeders/Equipment
Tripped
Name of
Substations/Line
affected by fault
Reason of Fault Relay indication and operation
Exact location of fault
(Line
segment/substation)
Remarks
1 12.04.2018 15:18 12.04.2018 15:42 0:24 30 66kV Bhutan Concast 66kV Bhutan Concast tripped 51N Line66kV supply from malbase got trip at
their end
2 25.04.2018 13:58 25.04.2018 14:20 0:22 31.2
50MVA Transformer
and 66kV Bhutan
Concast
66kV BFAL and all
11kV outgoing FeederTripped 50N.51N Line
Tripped due to overload as 66kV
Supply Failed from Malbase SS and
Kept Bhutan Concast Breaker open at
singhigaon after approval from BPSO.
Heavy rainfall with thunder and
lightning at the time of tripping.
Heavy rainfall with thunder and
lightning at the time of tripping.The
feeder couldn’t be restored as 400kV
Malbase - Siliguri Feeder and
200MVA ICT got tripped. The priority
to restore 400kV Malbase - Siliguri
Feeder and 200MVA ICT was given
as per BPSO.
Heavy Rainfall with thunder and
lightning at the time of tripping. The
restoration of power took time as
400kV Tala - Malbase Feeder got
tripped at Tala end.
Test charge was done at 14:15 hrs but
could not hold as Y-ph insulator was
found broken at switching station of
Lhaki Steel.
Transmission System Performance Report Second Quarterly Report-2018
32 | P a g e
66/33/11kV Lobeysa substation
Sl. NoDate of
Tripping
Time of
Outage
Date of
Normalizatio
n
Time of
Fault
cleared
Duration of
Outages
Load before
Outage (MW)
Name of
Feeders/Equipment
Tripped
Name of
Substations/Line
affected by fault
Reason of FaultRelay indication and
operation
Exact location of fault (Line
segment/substation)Remarks
1 05/04/2018 15:01hrs 05/04/2018 15:25hrs 0:24 0.82066kV LSA- 66kV
S/KHAAll outgoing feeders Linefault NA Semtokha end
2 05/04/2018 15:01hrs 05/04/2018 15:25hrs 0:24 3.90066kV LSA- 66kV
Basochu feederAll outgoing feeders Linefault NA Baoschu end
3 21/04/2018 11:28hrs 23/04/2018 14:10hrs 2:42 42Transformer-
I(5MVA,66/11kV)NA
LV side compound
chamber blast
Diff. relay (R&Y) phase, INST
&IDMT O/C on R&Y ohaseLobeysa ss
66/11kV 5MVA
Transformer-I,tripped
on Diff. protection and
INST &IDMT O/C on
R&Y phase along with
11kV feeder-4
66/33/11kV Gomtu substation
Sl. NoDate of
Tripping
Time of
Outage
Date of
Normalization
Time of
Fault
cleared
Duration of
Outages
Load before
Outage
(MW)
Name of
Feeders/Equipment
Tripped
Name of
Substations/Line
affected by fault
Reason of Fault Relay indication and operation
Exact location of fault
(Line
segment/substation)
Remarks
1 05.04.2018 9:36 05.04.2018 9:51 0:15 18.55
66kV Dhamdum
Incomer (66kV
Dhamdum-Gomtu
feeder)
Both incomer failed O/C 86A &86B optd at Dhamdum Ss. Dhamdum substation
Both 220/66 kV transformers I and II
tripped at Dhamdum substation. The
line was charged from Dhamdum after
necessary action at their end.
2 05.04.2018 09:46 05.04.2018 21:36 11:50 8.94
66kV Phuentsholing
Incomer (66kV Pling-
Gomtu feeder)
Both incomer failed O/C IDMTL O/C. 51AX,51BX , 51CX Line segment
Patrolling was done by TMD along
the line. No external disturbances was
found. So line was charged at 21:36hrs
with charging code no. 250 from
BPSO. Line stood normal.
3 22.04.2018 00:05 0.7666/33kV 5MVA
Transformer
33kV I/C and 33kV
Samtse feeder.O/C
IDMTL with High Set 50Y & Trip relay
86 HV (Both) optd. Indication: OLTC
Buchhlz optd & Differential protection
operated.
Substation
After testing, they have found that
Rphase winding got burned which
has also effected the Bphase winding.
The transformer need repairing and is
still in breakdown.
220/66/33kV Dhamdum substation
Sl. NoDate of
Tripping
Time of
Outage
Date of
Normalization
Time of
Fault
cleared
Duration of
Outages
Load before
Outage
(MW)
Name of
Feeders/Equipment
Tripped
Name of
Substations/Line
affected by fault
Reason of Fault Relay indication and operation
Exact location of fault
(Line
segment/substation)
Remarks
1 05.04.2018 9:46 05.04.2018 9:51 0:05 10.150/63MVA transformer
I&IIDhamdhum substation Transient fault
86A TRP RLY OPTD, 86B TRP RLY
OPTD & SBEF(51NS) tripSubstation
At 9:46hrs both HV & LV of 50/63
MVA transformer got tripped.
2 17.04.2018 20:45 17.04.2018 21:44 0:59 9.9750/63MVA transformer
I&IIDhamdhum substation
86A TRP RLY OPTD, 86B TRP RLY
OPTD Substation
The fault was at the sending end
(malbase). 202Q52 was not opereated
but both the 50/63 MVA transformer's
breaker (HV &LV ) got triped at our
end
3 21.04.2018 19:24 21.04.2018 19:37 0:13 -20.83 220 kV Malbase Dhamdum substation Y & B phase fault
86A TRP RLY OPTD, 86B TRP RLY
OPTD. GENERAL TRIP, Zone 1 Trip,
Yphase fault, Bphase Fault, VT fuse fail
SubstationThere was a fault between the Y
phase and B phase. .
66/33/11kV Gedu substation
Sl. NoDate of
Tripping
Time of
Outage
(Hrs)
Date of
Normalization
Time of
Fault
cleared
(Hrs)
Duration of
Outages
Load before
Outage
(MW)
Name of Feeders
Tripped
Name of
Substations/Line
affected by fault
Reason of Fault Relay indication and operation
Exact location of fault
(Line
segment/substation)
Remarks
1 06.04.2018 18:15 06.04.2018 18:18 0:03 0.36 8MVA Transformer33KV Gurung dara fdr
ITransient
1. O/C relay (B phase).
2. Tripping relay 86 Line
2 07.04.2018 15:18 07.04.2018 15:21 0:03 0.29
66/33/11kV, 5MVA
transformer & 33kV
Incomer II
33KV Gurung dara fdr
IITransient
5MVA TR 1. REF relay.
2. Tripping relay 86
33kV INCOMER II 1. E/F relay
(INST) 2. Tripping relay 86
Line
3 07.04.2018 15:18 07.04.2018 15:40 0:32 0.25 8MVA Transformer33KV Gurung dara fdr
I
Weather condtion:
Heavy rainfall with
lightning.
1. O/C relay (R&Y phase).
2. Tripping relay 86 Substation
8MVA transformer got tripped due to
flashing form 33kV Incomer I.
4 19.04.2018 15:36 19.04.2018 15:43 0:07 0.665MVA transformer I &
II11kV feeders. Transient
1. O/C relay (R,Y& B phase).
2. Tripping relay 86 Line
5 28.04.2018 16:30 28.04.2018 16:32 0:02 0.33 8MVA Transformer33KV Gurung dara fdr
ITransient
1. O/C relay (R & B phase).
2. Tripping relay 86 Line
6 28.04.2018 17:09 28.04.2018 17:14 0:05 0.566kV Chukha-Gedu
SectionGedu blackout
Tripped at Chukha
end.Weather
condtion: Heavy
rainfall with
lightning.
chukha end
Transformer under break down.
66/33/11kV Phuentsholing substation
Sl. NoDate of
Tripping
Time of
Outage
(Hrs)
Date of
Normalization
Time of
Fault
cleared
(Hrs)
Duration of
Outages
Load before
Outage
(MW)
Name of Feeders
Tripped
Name of
Substations/Line
affected by fault
Reason of Fault Relay indication and operation
Exact location of fault
(Line
segment/substation)
Remarks
1 05.04.2018 9:46 05.04.2018 9:57 0:11 8.89 66KV Pling-Gomtu 66KV Pling-Gomtu Temporary 86,186 & Dist.prot.optd Line
Test charged the feeder after getting
charging code from BPSO stood
normal. During the time of tripping
there was heavy rainfal, lightining and
thundering.
2 05.04.2018 10:00 05.04.2018 10:20 0:20 8.89 66KV Pling-Gomtu 66KV Pling-Gomtu Temporary 86,186 & Dist.prot.optd Line
Test charged the feeder as per the
instruction from BPSO that breaker at
Gomtu end was kept open and
charged the feeder stood normal.
During the time of tripping there was
heavy rainfal, lightining and
thundering.
3 05.04.2018 10:26 05.04.2018 21:36 11:10 8.89 66KV Pling-Gomtu 66KV Pling-Gomtu Temporary 86,186 & Dist.prot.optd Line
Informed to TMD Pling for line
petrolling they had done the line
petrolling but no fault was found in
line, so after getting clerance from
TMD, Pling and charging code from
BPSO test charged the feeder stood
normal.
2 05.04.2018 09:46 05.04.2018 21:36 11:50 8.94
66kV Phuentsholing
Incomer (66kV Pling-
Gomtu feeder)
Both incomer failed O/C IDMTL O/C. 51AX,51BX , 51CX Line segment
Patrolling was done by TMD along
the line. No external disturbances was
found. So line was charged at 21:36hrs
with charging code no. 250 from
BPSO. Line stood normal.
Transmission System Performance Report Second Quarterly Report-2018
33 | P a g e
220/66/11kV Semtokha substation
Sl. NoDate of
Tripping
Time of
Outage
Date of
Normalizatio
n
Time of
Fault
cleared
Duration of
Outages
Load before
Outage (MW)
Name of
Feeders/Equipment
Tripped
Name of
Substations/Line
affected by fault
Reason of FaultRelay indication and
operation
Exact location of fault (Line
segment/substation)Remarks
1 4/5/2018 1459hrs 4/5/2018 1524hrs 0.02 -22.84220kV Semtokha-
Rurichu feeder
Semtokha, D/ling,
Olakhaetc.Trip at Rurichu end earth fault Rurichu end
66/33kV Olakha substation
Sl. NoDate of
Tripping
Time of
Outage
Date of
Normalizatio
n
Time of
Fault
cleared
Duration of
Outages
Load before
Outage (MW)
Name of
Feeders/Equipment
Tripped
Name of
Substations/Line
affected by fault
Reason of FaultRelay indication and
operation
Exact location of fault (Line
segment/substation)Remarks
1 5/4/2018 14:58 5/4/2018 15:45 0:47 14.3 66kV Olakha -
Semtokha
Olakha & All outgoing
feeder
Supply failed from
Rurichu.
No relay operated at Olakha
SubstationRurichu
Whole supply failed
from Rurichu at
14:58hrs ( Black out)
and Supply resumed
Via Jemina 15:15hrs.
2 5/4/2018 18:06 5/4/2018 18:08 0:02 5.366KV Olakha - Jemina
Fdr.66KV Jemina Fdr. Tempoary fault
O/C &E/F Proth relay 67.
1.Device Trip, 2.R phase over
current pick up. 4.B phase
over current pick up and
tripping relay 86.
line segments
Reset the relay and
test charged the
feeders and stood
normal.
3 29/04/2018 9:14 29/04/2018 9:16 0:02 6.7 66/33kV, 20MVA TR-IAll 33KV Outgoing
feeders.
Tripped due to tripping
of DPH- II,Fdr.
1.TRAFO DIFFL PROTN.
Relay 86 2.Master trip relay
86. 3.Indication 1,3,4&5
1.Device Trip 3.y phase
Differential Trip 4.B phase
differenttial Trip
5.Differenttial Trip.
Tempoarary Fault
Reset the relay and
test charged the
feeders and stood
normal.
66/33/11kV Jemina substation
Sl. NoDate of
Tripping
Time of
Outage
Date of
Normalizatio
n
Time of
Fault
cleared
Duration of
Outages
Load before
Outage (MW)
Name of
Feeders/Equipment
Tripped
Name of
Substations/Line
affected by fault
Reason of FaultRelay indication and
operation
Exact location of fault (Line
segment/substation)Remarks
Chumdo switching station
Sl. NoDate of
Tripping
Time of
Outage
Date of
Normalizatio
n
Time of
Fault
cleared
Duration of
Outages
Load before
Outage (MW)
Name of
Feeders/Equipment
Tripped
Name of
Substations/Line
affected by fault
Reason of FaultRelay indication and
operation
Exact location of fault (Line
segment/substation)Remarks
66/33/11kV Paro substation
Sl. NoDate of
Tripping
Time of
Outage
Date of
Normalizatio
n
Time of
Fault
cleared
Duration of
Outages
Load before
Outage (MW)
Name of
Feeders/Equipment
Tripped
Name of
Substations/Line
affected by fault
Reason of FaultRelay indication and
operation
Exact location of fault (Line
segment/substation)Remarks
66/11kV Haa substation
Sl. NoDate of
Tripping
Time of
Outage
Date of
Normalizatio
n
Time of
Fault
cleared
Duration of
Outages
Load before
Outage (MW)
Name of
Feeders/Equipment
Tripped
Name of
Substations/Line
affected by fault
Reason of FaultRelay indication and
operation
Exact location of fault (Line
segment/substation)Remarks
1 4/1/2018 18:08 4/1/2018 18:11 0:03 2.55 66kV incomer All outgoing fdrs. Incomer failed Nil Supply failed from Chumdo
66/33kV Watsa substation
Sl. NoDate of
Tripping
Time of
Outage
Date of
Normalizatio
n
Time of
Fault
cleared
Duration of
Outages
Load before
Outage (MW)
Name of
Feeders/Equipment
Tripped
Name of
Substations/Line
affected by fault
Reason of FaultRelay indication and
operation
Exact location of fault (Line
segment/substation)Remarks
66/33/11kV Dechencholing substation
Sl. NoDate of
Tripping
Time of
Outage
Date of
Normalizatio
n
Time of
Fault
cleared
Duration of
Outages
Load before
Outage (MW)
Name of
Feeders/Equipment
Tripped
Name of
Substations/Line
affected by fault
Reason of FaultRelay indication and
operation
Exact location of fault (Line
segment/substation)Remarks
1 05.04.18 15:00 05.04.18 15:24 0:24 2.914 I/C S/kha Black OutSupply failed from
S/kha._ _ _
2 08.04.18 6:02 08.04.18 6:05 0:03 1.453 10 mVA Trf. (I+II) Black Out Over current 50 B, 56 AHV, 56 BHV _ _
No Tripping
No Tripping
No Tripping
No Tripping
Transmission System Performance Report Second Quarterly Report-2018
34 | P a g e
May, 2018
400/220/66/11kV Malbase substation
Sl. NoDate of
Tripping
Time of
Outage
Date of
Normalization
Time of
Fault
cleared
Duration of
Outages
Load before
Outage
(MW)
Name of
Feeders/Equipment
Tripped
Name of
Substations/Line
affected by fault
Reason of Fault Relay indication and operation
Exact location of fault
(Line
segment/substation)
Remarks
1 01.05.2018 15:36 01.05.2018 15:41 0:05 3350/63MVA Trasformer -
III
50/63MVA Trasformer -
III Trip
OLTC -BUCH-trip, 27 trip, 86A OPTD. Trip
Values: IL1=84.56A<0.75deg,
IL2=103.58A<-126.67deg,
IL3=712.0A<75.43deg,
IL4=640.00A<71.61deg
Substation
Heavy rainfall with
thunder and lightning at
the time of tripping.
2 01.05.2018 15:36 01.05.2018 15:42 0:06 3050/63MVA Trasformer -
I (LV Side)
50/63MVA Trasformer -
I (LV Side)Trip
General trip,86 operated,IEF-50N- Trip Trip
Values: IL1=322.38A<-
11.14deg, IL2=3460.15A<174.66deg,
IL3=3101.83A<43.36deg, IL4=2683.81A<111.46deg
Substation
3 07.05.2018 17:53 07.05.2018 19:10 0:17 73 200MVA ICT 200MVA ICT Trip
RET 521 Operated. Trip
Values: IL1=0.056A<52deg.
IL2=.017A<17.2deg. IL3=0.181A<-
161.5deg. IL4=1A<-11.05 deg
Substation
220kV bus Coupler, 220kV
Malbase-Samtse feeder,
50/63MVA Transformer I
& III tripped along with
the ICT.
4 07.05.2018 17:53 07.05.2018 19:12 0:19 68220kV Malbase -
Samtse Feeder.
220kV Malbase -
Samtse Feeder.Trip - Line
5 07.05.2018 17:53 07.05.2018 19:18 0:15 3650/63MVA Trasformer -
I
50/63MVA Trasformer -
ITrip - Substation
6 07.05.2018 17:53 07.05.2018 19:22 0:29 3650/63MVA Trasformer -
III
50/63MVA Trasformer -
III Trip - Substation
7 07.05.2018 21:50 08.05.2018 0:33 2:43 77 200MVA ICT 200MVA ICT Trip
RET 521 operated. Trip
Values:
IL1=0.097A<51.86deg.
IL2=0.076A<-110.2deg.
IL3=0.028A<19.92deg.
Substation
All the feeders got tripped
at the same time. ICT,
50/63MVA transformers I
& III, and 220kV bus
coupler were charged at
22:
8 07.05.2018 21:50 08.05.2018 1:14 3:24 17220kV Malbase -
Samtse Feeder.
220kV Malbase -
Samtse Feeder.Trip
B/B TRIP,CARRIER FAIL,R-PH CB OPEN,Y-PH CB
OPEN,B-PH CB OPEN Trip Values:
IL1=165.4A<346.1deg,
IL2=114.2A<229.1deg,
IL3=158.6A<104.2deg, IL4=20.61A,<385.5deg.
Line
9 07.05.2018 21:50 08.05.2018 0:34 2:44 3050/63MVA Transformer
I
50/63MVA
Transformer ITrip
DIFF START L1 Trip
Values: IL1=0.01A<-
178.64deg. IL2=0.05A<33.2deg.
IL3=0.15A<-5.42deg.
IL4=0.18A<3.31deg.
Substation
10 07.05.2018 21:50 08.05.2018 0:36 2:46 3050/63MVA Transformer
III
50/63MVA
Transformer IIITrip
BBP-OPTD Trip
Values: IL1=0.01A<-
137.11deg. IL2=0.12A<-163.67deg.
IL3=0.14A<-74.80deg.
Substation
11 07.05.2018 21:50 10.05.2018 15:50 66;00 - 220kV Bus Coupler 220kV Bus Coupler Trip - Substation
12 07.05.2018 21:50 18.05.2018 10:49 252;59 - 66kV Bus Coupler 66kV Bus Coupler Trip
The feeder was hand
tripped as per the
instruction received from
BPSO
13 09.05.2018 7:35 09.05.2018 8:05 0:30 64220kV Malbase -
Samtse Feeder.
220kV Malbase -
Samtse Feeder.Trip
START-B-PH,M1-TRIP,TRIP- R PH,TRIP-Y PH,TRIP-
B PH,START NEU, Zone-2 Start,Zone-3 Start,Zone-2
TRIP,Carrier fail,M1/BC BLOC AR,R-PH CB Open,Y-
PH CB Open,B-PH CB Open. Trip Values:
IL1=18.10A<101.4deg,
IL2=18.05A<334.8deg,
IL3=2693A<41.68deg,
IL4=2710A<41.61deg
Line
Heavy Rainfall with
thunder and lightning at
the time of tripping.
14 09.05.2018 8:11 09.05.2018 8:20 0:09 -52220kV Chukha -
Malbase Feeder.
220kV Chukha -
Malbase Feeder.Trip
General Trip,Trip-R PH,Trip-Y PH,Trip-B PH,Start
Nue,Zone 1 start,Zone 2 start,Zone 1 tripped.
Trip Values:
IL1=2477A<281.4deg,
IL2=243.3A<97.6deg,
IL3=146.7A<71.43deg,
IL4=2015A<284.3deg
Fault loop = L1-N,
Distance 7.2km
15 22.05.2018 21:42 22.05.2018 21:58 0:16 13220kV Malbase -
Samtse Feeder.
220kV Malbase -
Samtse Feeder.Tripped
M-1 TRIP,TRIP-R-PH,TRIP-Y-PH,TRIP-B-PH,START-
R-PH,START- Y-PH,START-B-PH,START-
NEU,ZONE-1-START,ZONE-2-START,ZONE-3-
START,ZONE-1-TRIP,CARRIER FAIL,M1 CARRI
SEND Trip Values:
I1=3261A<286deg, I2=3363A<160.3deg,
I3=2221A<38.16deg,
I4=790A<227.3deg.
FAULT LOOP=L1-
L2,Distance=30kM
ICT Tripped along with
Samtse Feeder. Heavy
Rainfall with thunder and
lightning at the time of
tripping.
16 22.05.2018 21:42 22.05.2018 21:48 0:06 154 200MVA ICT 200MVA ICT Tripped No data Displayed
17 23.05.2018 2:07 23.05.2018 2:27 0:20 11220kV Malbase -
Samtse Feeder.
220kV Malbase -
Samtse Feeder.Tripped
M-1 TRIP,TRIP-R-PH,TRIP-Y-PH,TRIP-B-PH,START-
B-PH,START-NEU,ZONE-2-START,ZONE-3-
START,ZONE-2-TRIP,CARRIER FAIL,M1/BC BLOC
AR R-PH CB OPEN,Y-PH CB OPEN,B-PH CB OPEN.
Trip Values:
I1=59.51A<233.5deg,
I2=131.4A<228.0deg,
I3=2435A<43.63deg,
I4=2245A<43.24deg.
Heavy rainfall with
thunder and lightning at
the time of tripping.
18 23.05.2018 2:55 23.05.2018 3:26 0:31 11220kV Malbase -
Samtse Feeder.
220kV Malbase -
Samtse Feeder.Tripped
M-1 TRIP,TRIP-R-PH,TRIP-Y-PH,TRIP-B-PH,START-
R-PH,START-B-PH,START-NEU,ZONE-2-
START,ZONE-3-START,ZONE-2-TRIP,CARRIER
FAIL,M1/BC BLOC AR,R-PH CB OPEN,Y-PH CB
OPEN,B-PH CB OPEN. Trip Values:
I1=3157A<272deg,
I2=92.39A<193deg,
I3=3303A<51.41deg,
I4=2240A<343.5deg.
At 02:55Hrs 400/220kV
200MVA ICT both HV &
LV tripped and Charged at
03:03Hrs. 50/63MVA
Transformer III tripped at
02:54Hrs and charged at
03:36Hrs. Heavy rainfall
with thunder and lightning
at the time of tripping.
19 23.05.2018 4:03 23.05.2018 17:45 13:42 1150/63MVA Transformer
III
50/63MVA
Transformer IIITripped
OLTC -BUCH-trip Trip
Values: I1
= 74.03A<11.81deg I2 =
58.17A<-100.76deg I3 =
31.81<151.86deg I4 =
66.40A<-59.65deg
The transformer couldn’t
hold while charging.
20 23.05.2018 4:52 23.05.2018 5:01 0:09 11220kV Malbase -
Samtse Feeder.
220kV Malbase -
Samtse Feeder.Tripped
M-1 TRIP,TRIP-R-PH,TRIP-Y-PH,TRIP-B-PH,START-
B-PH,START-NEU,ZONE-1-START,ZONE-2-
START,ZONE-3-START,ZONE -1-TRIP,CARRIER
FAIL,M1 CARRI SEND,R-PH CB OPEN,Y-PH CB
OPEN,B-PH CB OPEN. Trip Values:
I1=16.36A<105.1deg,
I2=16.63A<333.5deg, I3=4915A<42.24deg,
I4=4932A<42.14deg.
Heavy rainfall with
thunder and lightning at
the time of tripping.
21 23.05.2018 6:03 23.05.2018 6:30 0:27 11220kV Malbase -
Samtse Feeder.
220kV Malbase -
Samtse Feeder.Tripped
M-1 TRIP,TRIP-R-PH Trip
Values: I1=77.44A<206.8deg,
I2=97.35A<242.8deg,
I3=4091A<42.4deg,
I4=3921A<42.2deg.
FLT LOOP= L3-N
DISTANCE=26.6km
Heavy rainfall with
thunder and lightning at
the time of tripping.
22 23.05.2018 6:58 23.05.2018 7:18 0:20 13220kV Malbase -
Birpara Feeder
220kV Malbase -
Birpara FeederTripped
AR-OPTD Trip
Values: I1=1.786A<161.5deg,
I2=0A<0deg, I3=0A<0deg,
I4=0A<109.4deg.
23 23.05.2018 9:33 23.05.2018 9:35 0:02 117 200MVA ICT 200MVA ICT Tripped
51-start,86optd,GENERAL TRIP,IEF-50N-TRIP Trip
Values: HV R
Ph.=(FWD)IR=1032A ,HV Y
Ph.=(FWD) IY=180.8A, HV B
Ph.=(FWD)<LS>IDMTL IB=1101A, Earth
fault (FWD)IDMTL IN=693.4A
LV R Ph.=(REV)IR=575.2A, LV Y
Ph.=(FWD)(REV)IDMTL IY=660.9A, LV B
Ph.=(FWD)IDMTL IB=1899A, Earth fault
(FWD)IDMTL <HS1>IN=3028A.
400kV Siliguri feeder III
and Tala Feeder III was
tripped at the same time at
their end. Heavy rainfall
with thunder and lightning
at the time of tripping.
24 28.05.2018 19:18 28.05.2018 19:42 0:24 158400kV Malbase -
Siliguri Feeder.
400kV Malbase -
Siliguri Feeder.Tripped
Main-I- Trip,line-CB-open-R,CAR-RCV-MI,Main2-
CAR-RCV,Main2-Trip,TIE-CB-OPEN-R,MI-CAR-
SEND,ZMI-Trip,Fuse Fail,ZM2-StartZM3-Start,Time-
Sync-ERR Trip Values:
I1=3604A<247.9deg, I2=280.3A<280deg
I3=3808A<69.89deg
I4=76.06A<275.2deg.
Stormy weather at the time
of tripping.
25 31.05.2018 14:05 31.05.2018 14:07 0:02 121 200MVA ICT 200MVA ICT Tripped
Diff. R-Ph.optd.,86A & 86Boptd,OLTC oil surge Trip.
Trip Values: IL1=141.9A<-
12.05deg, IL2=60.81A<-176.3 deg,
IL3=60.45A<150 deg.
220/66/11kV Singhigaon substation
Sl. NoDate of
Tripping
Time of
Outage
Date of
Normalization
Time of
Fault
cleared
Duration of
Outages
Load before
Outage
(MW)
Name of
Feeders/Equipment
Tripped
Name of
Substations/Line
affected by fault
Reason of Fault Relay indication and operation
Exact location of fault
(Line
segment/substation)
Remarks
No Tripping
Transmission System Performance Report Second Quarterly Report-2018
35 | P a g e
66/33/11kV Phuentsholing substation
Sl. NoDate of
Tripping
Time of
Outage
(Hrs)
Date of
Normalization
Time of
Fault
cleared
(Hrs)
Duration of
Outages
Load before
Outage
(MW)
Name of Feeders
Tripped
Name of
Substations/Line
affected by fault
Reason of Fault Relay indication and operation
Exact location of fault
(Line
segment/substation)
Remarks
1 07.05.2018 17:53 07.05.2018 18:20 0:27 1.62 66KV Pling-Malbase Gomtu,Pling Temporary Nil Malbase
2 07.05.2018 18:55 07.05.2018 18:58 0;03 0 66KV Pling-Malbase Gomtu,Pling Temporary Nil Malbase
3 07.05.2018 19:08 07.05.2018 19:12 0:04 2.52 66KV Pling-Malbase Gomtu,Pling Temporary Nil Malbase
4 07.05.2018 21:50 08.05.2018 12:54 17:04 3.35 66KV Chukha-Pling Gomtu,Pling Temporary 86 Malbase
5 07.05.2018 21:57 18.05.2018 10:53 264;56 2.29 66KV Pling-Malbase Gomtu,Pling Temporary Nil Malbase
6 22.05.2018 21:20 22.05.2018 22:20 19:42 4.42 66KV Chukha-Pling Nil Temporary 86 &186 Line
7 23.05.2018 4:03 23.05.2018 4:34 0:37 10.11 66KV Chukha-Pling Nil Temporary 86 &186 Line
8 23.05.2018 4:05 23.05.2018 6:05 2:00 8.63 66KV Pling-Gomtu Nil Temporary 86 &186 Line
9 23.05.2018 23:55 24.05.2018 0:15 0:20 7.84 66KV Chukha-Pling Nil Temporary 86 &186 Line
10 28.05.2018 18:16 28.05.2018 20:07 1:51 5.34 66KV Chukha-Pling Nil Temporary 86 &186 Line
66/33/11kV Gomtu substation
Sl. NoDate of
Tripping
Time of
Outage
Date of
Normalization
Time of
Fault
cleared
Duration of
Outages
Load before
Outage
(MW)
Name of
Feeders/Equipment
Tripped
Name of
Substations/Line
affected by fault
Reason of Fault Relay indication and operation
Exact location of fault
(Line
segment/substation)
Remarks
1 07.05.2018 22:45 08.05.2018 20:12 21:27 4.57 66kV Gomtu-P/Ling
There was fire in 11
kV control room at
Phuentsholing
Substation
CB and Isolator opened for Phuentsholing Line. P/Ling Substation
After the incident at
Phuentsholing substation
the CB and isolator for
Phuentsholing line at our
end was kept open.
2 02.05.2018 15:36 02.05.2018 15:47 0:11 11.5266kV Incomer
DhamdumWhole Gomtu
Tr. III & IV HV/LV
side tripped at
Malbase
Substation.
B Phase Fault optd. at Gomtu Substation Malbase Substation
Heavy rainfall at Malbase
triping the Dhamdum line
and simultaneously
tripping Gomtu line. At
15:47 hrs Dhamdum line
was charged to normal.
3 07.05.2018 17:55 07.05.2018 18:20 0:25 14.7666kV Incomer
DhamdumWhole Gomtu
Internal problem at
Malbase
substation.
No relay or CB operationa at our end. Malbase Substation
4 07.05.2018 18:55 07.05.2018 18:58 0:03 14.7666kV Incomer
DhamdumWhole Gomtu Malbase Substation
5 07.05.2018 19:08 07.05.2018 19:12 0:04 5.366kV Incomer
DhamdumWhole Gomtu Malbase Substation
6 07.05.2018 21:50 07.05.2018 22:00 0:10 12.566kV Incomer
DhamdumWhole Gomtu Malbase Substation
7 07.05.2018 22:03 07.05.2018 23:20 0:17 12.566kV Incomer
DhamdumWhole Gomtu Malbase Substation
8 08.05.2018 0:05 08.05.2018 1:17 1:12 1.3566kV Incomer
DhamdumWhole Gomtu Malbase Substation
9 09.05.2018 7:14 09.05.2018 8:38 1:24 11.566kV Incomer
Dhamdum
Heavy lightning
and rain.Z COM trip & Yphase fault indicated at our end. Damdum Substation
10 23.05.2018 4:45 23.05.2018 5:02 0:17 7.1666kV Incomer
DhamdumWhole Gomtu
50/63MVA
transformer I at
Dhamdum
Substation which
feeds Gomtu
substation got
tripped
Relay operated at Dhamdum substation- 86 A &B Dhamdum substation
66kV Dhamdum line
tripped at 4:45 hours due
to heavy rain, lightning
and thundering.
11 23.05.2018 5:35 23.05.2018 5:45 0:10 7.1666kV Incomer
DhamdumWhole Gomtu
Supply failed from
Damdum
substation
Relay tripped at Dhamdum substation- General trip.
Zone I trip, Y-Phase fault, B-Phase faultDhamdum substation
66kV Dhamdum line
tripped at 5:35 hours due
to heavy rain, lightning
and thundering. .
12 23.05.2018 6:04 23.05.2018 6:06 0:02 0.93966kV Incomer
DhamdumWhole Gomtu
Supply failed from
Damdum
substation
Dhamdum substation
66kV Damdum line tripped
at 6:04 hours due to heavy
rain and lightning.
220/66/33kV Dhamdum substation
Sl. NoDate of
Tripping
Time of
Outage
Date of
Normalization
Time of
Fault
cleared
Duration of
Outages
Load before
Outage
(MW)
Name of
Feeders/Equipment
Tripped
Name of
Substations/Line
affected by fault
Reason of Fault Relay indication and operation
Exact location of fault
(Line
segment/substation)
Remarks
1 01.05.2018 15:40 01.05.2018 15:47 0:07 6.94 50/63 MVA trf. Iand II Dhamdum substation Transient fault86A TRP RLY OPTD, 86B TRP RLY OPTD &
SBEF(51NS) trip
At 15:40hrs both HV & LV
of 50/63 MVA transformer
got tripped. We informed
to BPSO and test charged
against charging code 329.
2 07.05.2018 21:50 08.05.2018 1:14 3:24 89.09220 kV Malbase Samtse
feeder
Tripped from
malbasey .Non of the relay was operated .
Substation was blackout
during that time.
3 09.05.2018 7:11 09.05.2018 8:11 1:00 8.0450/63MVA transformer
IDhamdum substation 86 A &B Dhamdum substation
50/63MVA transformer
I&II and Gomtu feeder got
tripped.
4 09.05.2018 7:11 09.05.2018 8:11 1:00 8.0450/63MVA transformer
IIDhamdum substation 86 A &B Dhamdum substation
50/63MVA transformer
I&II and Gomtu feeder got
tripped.
5 09.05.2018 7:20 09.05.2018 8:47 1:27 54.78220 kV Singyegaon
feeder
220kV Singyegaon
substation.VT fuse fail. 86A&B relay optd.
CH No. 1 Fault mag 0.09A.
Fault ang. 143.49deg.
6 09.05.2018 7:11 09.05.2018 8:37 1:27 11.48 66 kV Gomtu feeder Dhamdum substationGeneral trip . Zone one trip R-phase fail VT fuse fail
86relay Opt
CH i. Fault mag 0.08A.
Fault ang. -9.90deg.
66/33/11kV Gedu substation
Sl. NoDate of
Tripping
Time of
Outage
(Hrs)
Date of
Normalization
Time of
Fault
cleared
(Hrs)
Duration of
Outages
Load before
Outage
(MW)
Name of Feeders
Tripped
Name of
Substations/Line
affected by fault
Reason of Fault Relay indication and operation
Exact location of fault
(Line
segment/substation)
Remarks
1 06.05.2018 11:36 06.05.2018 12:10 0:34 0.36 8MVA Transformer33KV Gurung dara fdr
I
The cause of
tripping was due to
flash over inside
the 33kV Incomer I
panel.
1. O/C relay R, Y& B phase). 2.
Tripping relay 86 Substation
Opened 33kV Incomer I
panel and found moisture
formation on panel & CTs.
2 10.05.2018 16:25 10.05.2018 16:28 0:03 0.29
66/33/11kV, 5MVA
transformer & 33kV
Incomer II
33KV Gurung dara fdr
II
Transformer got
tripped due to fault
on 33kV
Gurungdara fdr II.
5MVA TR 1. REF relay.
2. Tripping relay 86 33kV
INCOMER II 1. E/F relay (INST) 2.
Tripping relay 86
Line
3 10.05.2018 19:08 10.05.2018 19:10 0:02 0.22
66/33/11kV, 5MVA
transformer & 33kV
Incomer II
33KV Gurung dara fdr
II
Transformer got
tripped due to fault
on 33kV
Gurungdara fdr II.
5MVA TR 1. REF relay.
2. Tripping relay 86 33kV
INCOMER II 1. E/F relay (INST) 2.
Tripping relay 86
Line
4 21.05.2018 5:52 21.05.2018 5:55 0:03 0.45
66/33/11kV, 5MVA
transformer & 33kV
Incomer II
33KV Gurung dara fdr
II
Transformer got
tripped due to fault
on 33kV
Gurungdara fdr II.
5MVA TR 1. REF relay.
2. Tripping relay 86 33kV
INCOMER II 1. E/F relay (INST) 2.
Tripping relay 86
Line
5 22.05.2018 21:20 22.05.2018 21:25 0:05 2.4866kV Chukha-Pling
feederGedu blackout
Tripped at Chukha
end.Chukha end
6 22.05.2018 21:38 22.05.2018 21:43 0:05 2.4866kV Chukha-Pling
feederGedu blackout
Tripped at Chukha
end.Chukha end
7 23.05.2018 23:54 23.05.2018 0:05 0:11 1.9666kV Chukha-Pling
feederGedu blackout
Tripped at Chukha
end.Chukha end
8 28.05.2018 18:18 28.05.2018 18:34 0:16 1.6466kV Chukha-Pling
feederGedu blackout
Tripped at Chukha
end.Chukha end
Breaker at our end was in
healthy conditon.
Substation was blackout
as Chukha breaker got
Supply failed from
Malbase Substation due
to problem in 220/66 kV
50/63 MVA transformer III
at GIS Singhigaon
Substation
Heavy rainfall with
lightning.
Transmission System Performance Report Second Quarterly Report-2018
36 | P a g e
66/33/11kV Lobeysa substation
Sl. NoDate of
Tripping
Time of
Outage
Date of
Normalizatio
n
Time of
Fault
cleared
Duration of
Outages
Load before
Outage (MW)
Name of
Feeders/Equipment
Tripped
Name of
Substations/Line
affected by fault
Reason of FaultRelay indication and
operation
Exact location of fault (Line
segment/substation)Remarks
220/66/11kV Semtokha substation
Sl. NoDate of
Tripping
Time of
Outage
Date of
Normalizatio
n
Time of
Fault
cleared
Duration of
Outages
Load before
Outage (MW)
Name of
Feeders/Equipment
Tripped
Name of
Substations/Line
affected by fault
Reason of FaultRelay indication and
operation
Exact location of fault (Line
segment/substation)Remarks
66/33/11kV Dechenchholing substation
Sl. NoDate of
Tripping
Time of
Outage
Date of
Normalizatio
n
Time of
Fault
cleared
Duration of
Outages
Load before
Outage (MW)
Name of
Feeders/Equipment
Tripped
Name of
Substations/Line
affected by fault
Reason of FaultRelay indication and
operation
Exact location of fault (Line
segment/substation)Remarks
66/33kV Olakha substation
Sl. NoDate of
Tripping
Time of
Outage
Date of
Normalizatio
n
Time of
Fault
cleared
Duration of
Outages
Load before
Outage (MW)
Name of
Feeders/Equipment
Tripped
Name of
Substations/Line
affected by fault
Reason of FaultRelay indication and
operation
Exact location of fault (Line
segment/substation)Remarks
1 19/5/2018 8:45 19/5/2018 8:47 0:02 -11.566KV Olakha -
Semtokha
All the 33kV Incomer I
& II
66kV line was tripped
due to tripping of DHP
II.
TRAFO DIFFL PROTN
RELAY 87.1.Device
trip.3.Distacce
protection Y-E Trip and
5.Distance protection R-
Y Trip. Trip Relay 86.
RICB Substation, Thimphu
There was breaker
problem at RICB
Substation.
2 5/5/2018 7:22 5/5/2018 7:25 0:03 6.9 66/33kV 20MVA TR.I
66/33kV 20MVA TR.I
along with all the 33kV
outgoing feeders
Tripped due to tripping
of DPH- II,Fdr.
1.TRAFO DIFFL
PROTN. Relay 87.
2.Master trip relay 86.
3.Indication 1,3,4&5
1.Device Trip 3.y phase
Differential Trip 4.B
phase differential Trip
5.Differenttial Trip.
Dir. O/C & EF PROTN
RELAY 67. Indication
2&4. 2.R Phase over
current pickup. 4. B
phase over current
pickup.
Line Segments
Reset the relay and
test charged the
Transformer and stood
normal.
66/33/11kV Jemina substation
Sl. NoDate of
Tripping
Time of
Outage
Date of
Normalizatio
n
Time of
Fault
cleared
Duration of
Outages
Load before
Outage (MW)
Name of
Feeders/Equipment
Tripped
Name of
Substations/Line
affected by fault
Reason of FaultRelay indication and
operation
Exact location of fault (Line
segment/substation)Remarks
Chumdo switching station
Sl. NoDate of
Tripping
Time of
Outage
Date of
Normalizatio
n
Time of
Fault
cleared
Duration of
Outages
Load before
Outage (MW)
Name of
Feeders/Equipment
Tripped
Name of
Substations/Line
affected by fault
Reason of FaultRelay indication and
operation
Exact location of fault (Line
segment/substation)Remarks
66/33/11kV Paro substation
Sl. NoDate of
Tripping
Time of
Outage
Date of
Normalizatio
n
Time of
Fault
cleared
Duration of
Outages
Load before
Outage (MW)
Name of
Feeders/Equipment
Tripped
Name of
Substations/Line
affected by fault
Reason of FaultRelay indication and
operation
Exact location of fault (Line
segment/substation)Remarks
66/11kV Haa substation
Sl. NoDate of
Tripping
Time of
Outage
Date of
Normalizatio
n
Time of
Fault
cleared
Duration of
Outages
Load before
Outage (MW)
Name of
Feeders/Equipment
Tripped
Name of
Substations/Line
affected by fault
Reason of FaultRelay indication and
operation
Exact location of fault (Line
segment/substation)Remarks
66/33kV Watsa substation
Sl. NoDate of
Tripping
Time of
Outage
Date of
Normalizatio
n
Time of
Fault
cleared
Duration of
Outages
Load before
Outage (MW)
Name of
Feeders/Equipment
Tripped
Name of
Substations/Line
affected by fault
Reason of FaultRelay indication and
operation
Exact location of fault (Line
segment/substation)Remarks
No Tripping
No Tripping
No Tripping
No Tripping
No Tripping
No Tripping
No Tripping
No Tripping
Transmission System Performance Report Second Quarterly Report-2018
37 | P a g e
June, 2018
400/220/66/11kV Malbase substation
Sl. NoDate of
Tripping
Time of
Outage
Date of
Normalization
Time of
Fault
cleared
Duration of
Outages
Load before
Outage
(MW)
Name of
Feeders/Equipment
Tripped
Name of
Substations/Line
affected by fault
Reason of Fault Relay indication and operation
Exact location of fault
(Line
segment/substation)
Remarks
1 03.06.2018 19:13 03.06.2018 19:24 0:11 114 200MVA ICT 200MVA ICT Trip
400kV M CB open,400kV TI CB open
Trip Values: HV
L1=0.030A<-127.6deg, HV
L2=0.073A<58.63deg, HV
L3=0.075A<-66.53deg. LV
L1=.038A<-122.7deg, LV
L2=0.269A<deg, LV
L3= .027<153.3deg.
Substation
2 03.06.2018 19:17 03.06.2018 19:32 0:15 10220kV Malbase -
Samtse Feeder.
220kV Malbase -
Samtse Feeder.Trip
M-1 TRIP,TRIP R PH,TRIP Y PH,TRIP B PH
Trip Values:
I1=84.05A<352.6deg,
I2= 5353A<163.8deg,
I3=33.39A<24.93deg,
I4=5237A<163.6deg.
Line
3 03.06.2018 19:11 03.06.2018 20:43 0:55 2850/63MVA Transformer
I
50/63MVA
Transformer ITrip
DIFF trip. Trip
Values:
I1=123.22A<-2.58deg,
I2=68.72A<9.41deg,
I3=73.14A<96.68deg,
I4=184.77A<13.86deg.
Substation
4 03.06.2018 19:39 03.06.2018 21:08 0:29 2850/63MVA Transformer
II
50/63MVA
Transformer IITrip
86A OPTD,GENERAL TRIP,BBP- OPTD, LBB TRIP
Trip Values: I1=.11A<-
61.85deg, I2=.04A<144.41deg,
I3=.09A<-4.16deg.
Substation
5 03.06.2018 19:12 03.06.2018 19:52 0:40 3050/63MVA Transformer
III
50/63MVA
Transformer IIITrip
DIFF. TRIP,DIFF START, DIFF=HARM
BLK,DIFF=WAVW BLK Trip
Values: I1=154.49A<.37deg,
I2=91.93A<-9.28deg, I3=84.61A<-
84.77deg, I4=262.55A<15.56deg.
Substation
6 04.06.2018 14:05 04.06.2018 14:16 0:11 5220kV Chukha -
Malbase Feeder.
220kV Chukha -
Malbase Feeder.Trip - Line
The feeder got tripped at Chhukha end. Heavy
rainfall with thunder and lightening at the time of
tripping.
7 07.06.2018 14:52 07.06.2018 14:56 0:04 119 200MVA ICT 200MVA ICT Trip
86A optd,Main CB open,TIE CB open Trip
Values: I1=1146A,
I2=250.9A, I3=.1385A,
Neutral= 974.5A
Substation
8 07.06.2018 14:52 07.06.2018 15:00 0:08 83220kV Chukha -
Malbase Feeder.
220kV Chukha -
Malbase Feeder.Trip
TRIP-R- PH,TRIP-Y-PH,TRIP-B-PH, ZONE I TRIP
,General trip. Trip Values:
I1=4062A<277.5deg,
I2=258.9A<57.57deg,
I3=4744A<49.04deg,
I4=3807A<353.9deg
Line
9 10.06.2018 19:47 10.06.2018 19:53 0:06 91 200MVA ICT 200MVA ICT Trip
RET 521, 86 Optd. Trig signal, 400KV M CB OPEN &
400KV Ti CB open Trip Values:
IL1=71.29A<-178.8deg,
IL2=71.29A<58.79deg,
IL3=67.63A<-79.23deg,
Substation
10 10.06.2018 19:47 10.06.2018 19:55 0:08 11220kV Malbase -
Samtse Feeder.
220kV Malbase -
Samtse Feeder.Trip
REL=511, 86A OPTD. Trip
Values: IL1=71.75A<810.9eg,
IL2=3530A<-174.7deg,
IL3=4010A<32.62deg,
IL4=2342A<88.79deg
Line
11 10.06.2018 22:01 10.06.2018 22:07 0;06 12220kV Malbase -
Samtse Feeder.
220kV Malbase -
Samtse Feeder.Trip
86 tripped ,Main 1 tripped , R,Y,B Phase tripped ,
Zone 1 tripped.
Trip Values:
IL1=2915A<285.1deg,
IL2=74.77A<120.2deg,
IL3=118.1A<108.4deg,
IL4=2722A<284.6deg
Line
12 10.06.2018 22:58 10.06.2018 23:05 0:08 12220kV Malbase -
Samtse Feeder.
220kV Malbase -
Samtse Feeder.Trip
86 tripped ,Main 1 tripped , R,Y,B Phase tripped ,
Zone 2 Tripped Trip
Values:
IL1=120.1A<219.6.1deg,
IL2=219.2A<229.8deg,
IL3=3257A<41.65deg,
IL4=2918A<41.31deg
Line
13 19.06.2018 21:49 19.06.2018 21:58 0:09 - 66kV Bus Coupler 66kV Bus Coupler Trip
86 optd.,IOC-50 trip,General trip,IEF-50n trip.
TripValues:
IL1=72519A<82.00deg. IL2=6647.15A<-
61.03deg. IL3=304.60A<140.15deg.
Substation
14 19.06.2018 21:49 19.06.2018 21:59 0:10 28 66kV Pasakha Feeder I 66kV Pasakha Feeder I Trip 86 optd. Line
15 23.06.2018 2:00 23.06.2018 2:10 0:10 52 200MVA ICT 200MVA ICT Trip
86 optd, Main CB open, Tie CB open. Trip
Values: IL1=274.7A,
IL2=1143A,
IL3=254.5A,
IL4=1638A.
Substation
16 23.06.2018 2:00 23.06.2018 2:23 0:23 181400kV Tala - Malbase
Feeder
400kV Tala - Malbase
FeederTrip
86 optd.,Zone-I trip,dist.trip.
Trip Values:
IL1=130.3A,
IL2=3.788KA,
IL3=380.7A
Fault loop= Y phase-
Neutral. Distance=
11.78KM.
For 50/63MVA Transformer I, the HV SIDE
breaker was closed at 19:34 hrs but the LV side
breaker could not hold while charging. So at
20:43 hrs the LV side breaker charged through
emergency switch .i.e( PLUNGER) For
50/63MVA transformer II, the LV side breaker
was still on when it's 86 relay got operated. At
20:40hrs opened the LV side breaker with
emergency switch to charge its HV side
breaker.At 21.07hrs HV breaker charged and
21.08hrs LV side breaker close through
emergency switch. Heavy rainfall with thunder
and lightning at the time of tripping.
Tripped at the same time. Heavy rainfall with
thunder and lightning at the time of tripping.
Heavy lightning at the time of tripping. Weather
was bad at Samtse end at the time of tripping as
per the information received from operation
staff.
Heavy rainfall with thunder and lightning at the
time of tripping. The fault value of Pasakha
feeder - I could not be obtained as no data was
displayed in relay.
Rainfall with thunder and lightning at the time
of tripping. 400kV Tala Feeder III tripped at the
same time.
220/66/11kV Singhigaon substation
Sl. NoDate of
Tripping
Time of
Outage
Date of
Normalization
Time of
Fault
cleared
Duration of
Outages
Load before
Outage
(MW)
Name of
Feeders/Equipment
Tripped
Name of
Substations/Line
affected by fault
Reason of Fault Relay indication and operation
Exact location of fault
(Line
segment/substation)
Remarks
1 10.06.2018 19:47 10.06.2018 20:13 0:26 4Samtse-singhigaon
Fdr(206 bay)Trip 50/51 and 21 Line
samtse-singhigaon got trip on over current and
distance protection(21)
2 10.06.2018 22:01 10.06.2018 23:17 0:16 3.5Samtse-singhigaon
Fdr(206 bay)Trip 50/51 and 21 Line
samtse-singhigaon got trip on over current and
distance protection(21)
3 18.06.2018 4:41 18.06.2018 4:53 0:11 36 66kV BFAL Frd Trip 51Trip on Over current.R Phase=0.38kA
Y.Phase=0.44kA and B Phase=0.37.
66/33/11kV Phuentsholing substation
Sl. NoDate of
Tripping
Time of
Outage
(Hrs)
Date of
Normalization
Time of
Fault
cleared
(Hrs)
Duration of
Outages
Load before
Outage
(MW)
Name of Feeders
Tripped
Name of
Substations/Line
affected by fault
Reason of Fault Relay indication and operation
Exact location of fault
(Line
segment/substation)
Remarks
1 03.06.2018 19:39 03.06.2018 19:48 0:09 3.4 66KV Chukha-Pling Gedu Temporary 86 & 186 Line
2 04.06.2018 14:04 04.06.2018 14:37 0:33 7.25 66KV Chukha-Pling Gedu Temporary Dist. Prot, 86 & 186 Line
3 07.06.2018 14:59 07.06.2018 15:45 0:46 7.03 66KV Chukha-Pling Nil Temporary Dist. Prot, 86 & 186 LineTest charged the feeder at 15:11hrs but did not
withstand
4 13.06.2018 19:44 13.06.2018 20:47 1:03 4.86 66KV Pling-Gomtu Nil Temporary Dist. Prot, 86 & 186 Line
66/33/11kV Gomtu substation
Sl. NoDate of
Tripping
Time of
Outage
Date of
Normalization
Time of
Fault
cleared
Duration of
Outages
Load before
Outage
(MW)
Name of
Feeders/Equipment
Tripped
Name of
Substations/Line
affected by fault
Reason of Fault Relay indication and operation
Exact location of fault
(Line
segment/substation)
Remarks
1 13.06.2018 19:45 13.06.2018 19:57 0:12 4.980 66kV P/Ling Nil Over Current IDMTL O/C, 51Ax, 51Bx & 51Cx Line segment
66kV supply tripped on Over Current, thereby
informed to BPSO and P/ling Sub Station and
charged.
2 03.06.2018 19:17 03.06.2018 19:32 0:15 -13.2166kV Incomer
Dhamdum Whole Gomtu
Tripped at Malbase
substationMalbase S/s Transformer tripped at Malbase Substation.
3 11.06.2018 14:24 11.06.2018 14:29 0:05 -14.65066kV Incomer
Dhamdum
Supply feed from
P/Ling
Distance protection
operatedGeneral trip. Zone 2 trip. R PH faulty. YPH faulty Line segment
As per charging code no. 446. test charge was
done. Line stood to normal.
Transmission System Performance Report Second Quarterly Report-2018
38 | P a g e
220/66/33kV Dhamdum substation
Sl. NoDate of
Tripping
Time of
Outage
Date of
Normalization
Time of
Fault
cleared
Duration of
Outages
Load before
Outage
(MW)
Name of
Feeders/Equipment
Tripped
Name of
Substations/Line
affected by fault
Reason of Fault Relay indication and operation
Exact location of fault
(Line
segment/substation)
Remarks
1 01.06.2018 18:26 01.06.2018 18:30 0:04Trx=8.52,
Trx =8.57
220/66 kV, 50/63MVA
transformer I &IIDhamdum substation Transient fault 86A tripped 86 B tripped NA
2 06.06.2018 12:58 06.06.2018 1:03 0:05Trx=7.39,
Trx=7.39
220/66 kV, 50/63MVA
transformer I &IIDhamdum substation Transient fault 86A tripped 86 B tripped NA
3 10.06.2018 19:46 10.06.2018 20:13 0:27Mal = -11.62
Sing=-6.01
220kV Malbasey &
Singyegoan feederDhamdum substation Transient fault General trip,zone I trip, B-phase fault NA
4 10.06.2018 19:46 10.06.2018 20:08 0:22 Trx= 8.74X2
220/66 kV, 50/63MVA
transformer I &II(Both
HV&LV)
Dhamdum substation Transient fault 86A tripped 86 B tripped NA
5 10.06.2018 22:01 10.06.2018 22:09 0:08 -11.59 220kV malbase feeder Dhamdum substation Transient fault General trip,zone I trip, R-phase fault NA
6 10.06.2018 22:58 10.06.2018 23:06 0:08 -11.59 220kV malbase feeder Dhamdum substation Transient fault General trip,zone I trip, B-phase fault NA
7 11.06.2018 14:24 11.06.2018 14:30 0:06 8.19220/66 kV, 50/63MVA
I,IIDhamdum substation Transient fault 86A tripped 86 B tripped NA
8 11.06.2018 14:24 11.06.2018 14:31 0:07 8.16220/66 kV, 50/63MVA I
,II,L.V.Dhamdum substation Transient fault 86A tripped 86 B tripped NA
9 11.06.2018 14:24 11.06.2018 14:38 0:14 13.86 66KV GOMTU Dhamdum substation Transient fault General trip,zone 1,R n Y phase fault NA
66/33/11kV Gedu substation
Sl. NoDate of
Tripping
Time of
Outage
(Hrs)
Date of
Normalization
Time of
Fault
cleared
(Hrs)
Duration of
Outages
Load before
Outage
(MW)
Name of Feeders
Tripped
Name of
Substations/Line
affected by fault
Reason of Fault Relay indication and operation
Exact location of fault
(Line
segment/substation)
Remarks
1 04.06.2018 14:08 04.06.2018 14:15 0:07 1.5866kV Chukha-Pling
feederGedu blackout
Tripped at Chukha
end. Weather
condtion: Heavy
rainfall with
lightning.
Chukha end
2 19.06.2018 21:54 19.06.2018 21:57 0:03 1.9566kV Chukha-Pling
feederGedu blackout
Tripped at Chukha
end. Chukha end
3 22.06.2018 6:35 22.06.2018 6:40 0:05 0.285MVA Trsansfomer I &
IIAll 11kV feeders
Temporary
overcurrent.
Weather condition
was heavy rainfall
with lightning.
1. O/C relay (R,Y,B) INST.
2.Tripping relay 86Gedu Substation
66/33/11kV Lobeysa substation
Sl. NoDate of
Tripping
Time of
Outage
Date of
Normalizatio
n
Time of
Fault
cleared
Duration of
Outages
Load before
Outage (MW)
Name of
Feeders/Equipment
Tripped
Name of
Substations/Line
affected by fault
Reason of Fault Relay indication and operationExact location of fault (Line
segment/substation)Remarks
1 04/06/2018 14:02hrs 04/06/2018 14:19hrs 0:17 0.0766kV Lobeysa to
Basochu feederLobeysa substation Trip on fault NA grid fail
The line tripped at
14:02hrs from both the
end
220/66/11kV Semtokha substation
Sl. NoDate of
Tripping
Time of
Outage
Date of
Normalizatio
n
Time of
Fault
cleared
Duration of
Outages
Load before
Outage (MW)
Name of
Feeders/Equipment
Tripped
Name of
Substations/Line
affected by fault
Reason of Fault Relay indication and operationExact location of fault (Line
segment/substation)Remarks
1 6/4/2018 1405hrs 6/4/2018 1420hrs 0:15 -24.63220kV Semtokha-
ChukhaBlackout Thimphu Indian grid fail Main-I&II, TOV trip India grid
2 6/4/2018 1405hrs 6/4/2018 1429hrs 0:24 8.99220kV Semtokha-
RurichuBlackout Thimphu Indian grid fail India grid
Hand trip to normalise
supply from Chukha
3 6/28/2018 1220hrs 6/28/2018 1237hrs 0:17 9.01220/66kV 50/63mVA-I
transformer
Nill feed from
50/63MVA transformer-
II
Not known Back-up over current poerated Semtokha substation
4 6/12/2018 1653hrs 6/12/2018 1700hrs 0:07 -1.4566kV Semtokha-Lobesa
feederNill
Transient fault, trip
only at SemtokhaEarth fault Not known
66/33/11kV Dechenchholing substation
Sl. NoDate of
Tripping
Time of
Outage
Date of
Normalizatio
n
Time of
Fault
cleared
Duration of
Outages
Load before
Outage (MW)
Name of
Feeders/Equipment
Tripped
Name of
Substations/Line
affected by fault
Reason of Fault Relay indication and operationExact location of fault (Line
segment/substation)Remarks
1 04.06.18 14:05:00 04.06.18 14:18:00 0:13 2.86 I/C S/kha Black out.Supply failed from I/C
Semto-kha._ _ _
66/33kV Olakha substation
Sl. NoDate of
Tripping
Time of
Outage
Date of
Normalizatio
n
Time of
Fault
cleared
Duration of
Outages
Load before
Outage (MW)
Name of
Feeders/Equipment
Tripped
Name of
Substations/Line
affected by fault
Reason of Fault Relay indication and operationExact location of fault (Line
segment/substation)Remarks
1 8/6/2018 13:42 8/6/2018 13:43 0:01 4.2 20MVA TR.IOlakha S/S & all
outgoing feeders
Tripped due to tripping
of Gedakom
1.TRAFO DIFFL PROTN. Relay 87.
2.Master trip relay 86. 3.Indication
1,3,4&5 1.Device Trip 3.y phase
Differential Trip 4.B phase
differential Trip 5.Differenttial Trip.
Dir. O/C & EF PROTN RELAY 67.
Indication 134&5. 1.Divic tiip.3.Y
phase over current pick up 4. B
phase over current pickup.5.
BabesaTripped while test
charging Gedakom fdr.
2 8/6/2018 13:44 8/6/2018 13:45 0:01 4.2 20MVA TR.IOlakha S/S & all
outgoing feeders
Tripped due to tripping
of Gedakom
1.TRAFO DIFFL PROTN. Relay 87.
2.Master trip relay 86. 3.Indication
1,3,4&5 1.Device Trip 3.y phase
Differential Trip 4.B phase
differential Trip 5.Differenttial Trip.
Dir. O/C & EF PROTN RELAY 67.
Indication 134&5. 1.Divic tiip.3.Y
phase over current pick up 4. B
phase over current pickup.5.
BabesaTripped while test
charging Gedakom fdr.
3 29/06/2018 18:14 29/06/2018 18:18 0:04 4.1 20MVA TR.IOlakha S/S & all
outgoing feeders
Tripped due to tripping
of DPH II
1.TRAFO DIFFL PROTN. Relay
87..Indication , 1.Device Trip 3.y
phase Differential Trip 4.B phase
differential Trip 5.Differenttial Trip..
Trip relay 86. DIR. O/C&E/F PROTN
RELAY 67. 2.R phase over current
Pick up. 3. Y phase over current Pick
up
DPH IIDue to 33 kV DPH II
tripping.
4 30/06/2018 6:10 30/06/2018 6:14 0:04 2.3 20MVA TR.IOlakha S/S & all
outgoing feeders
Tripped due to tripping
of DPH II
1.TRAFO DIFFL PROTN. Relay
87..Indication , 1.Device Trip 3.y
phase Differential Trip 4.B phase
differential Trip 5.Differenttial Trip..
Trip relay 86. DIR. O/C&E/F PROTN
RELAY 67. 2.R phase over current
Pick up. 3. Y phase over current Pick
up
DPH IIDue to 33 kV DPH II
tripping.
5 30/06/2019 9:08 30/06/2019 9:11 0:03 1.9 20MVA TR.IOlakha S/S & all
outgoing feeders
Tripped due to tripping
of DPH II
1.TRAFO DIFFL PROTN. Relay
87..Indication , 1.Device Trip 3.y
phase Differential Trip 4.B phase
differential Trip 5.Differenttial Trip..
Trip relay 86. DIR. O/C&E/F PROTN
RELAY 67. 2.R phase over current
Pick up. 3.
DPH IIDue to 33 kV DPH II
tripping.
66/33/11kV Jemina substation
Sl. NoDate of
Tripping
Time of
Outage
Date of
Normalizatio
n
Time of
Fault
cleared
Duration of
Outages
Load before
Outage (MW)
Name of
Feeders/Equipment
Tripped
Name of
Substations/Line
affected by fault
Reason of Fault Relay indication and operationExact location of fault (Line
segment/substation)Remarks
No Tripping
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