bhutan power corporation...

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


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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


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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)


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


Eastern Grid Load (MW) Western Grid Load (MW) National Load (MW)

Lo

ad

(M

W)

Load Summary

April

May

June


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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


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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)


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)


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


Binaguri (MW) Birpara (MW) Salakoti and Rangia

(MW)

Exp

ort

(M

W)

Export to India

April

May

June


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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



2 Alert State 0.00%



0.00

10.00

20.00

30.00

40.00

50.00

60.00

70.00

80.00

90.00

100.00


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


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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



2 Alert State 0.13%



Graph 6.2.1. Bus frequency of Semtokha Substation




2 Alert State 0.13%




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%


Normal State

Alert State

Emergency State

Blackout/Other

99.87%

0.13%

0.00%

0.00%


Hydropower Plant

Normal State

Alert State

Emergency State

Blackout/Other


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6.3.Frequency for the month of June, 2018

Table 6.3.1. Bus frequency of Semtokha Substation



2 Alert State 0.13%



Graph 6.3.1. Bus frequency of Semtokha Substation




2 Alert State 0.00%




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%


Normal State

Alert State

Emergency State

Blackout/Other

96.77%

0.00%

0.00%

3.23%


Hydropower Plant

Normal State

Alert State

Emergency State

Blackout/Other


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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)


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


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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



2 Alert State 2.28%



Graph 7.1.3. Voltage Profile of 132/33/11kV Nangkor Substation

7.2.Voltage Profile for month of May, 2018.



1 Normal State 100.00% 100.00% 98.66%

2 Alert State 0.00% 0.00% 0.40%


4 Blackout/Other 0.00% 0.00% 0.54%



Sl. No. Operating State 220kV Bus Voltage 66kV Bus Voltage

1 Normal State 99.73% 99.87%




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%


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


100.00%

0.00%

0.00%

0.00%

400kV Bus Voltage at Malbase Substation

Normal State

Alert State


100.00%

0.00%

0.00%

0.00%


Normal State

Alert State

Emergency State

Blackout/Other


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2 Alert State 0.00%



Graph 7.2.3. Voltage Profile of 132/33/11kV Nangkhor Substation

7.3.Voltage Profile for the month of June, 2018



1 Normal State 96.77% 96.77% 95.83%

2 Alert State 0.00% 0.00% 0.94%


4 Blackout/Other 3.23% 3.23% 3.23%



Sl. No. Operating State 220kV Bus

Voltage

66kV Bus

Voltage

1 Normal State 99.60% 99.46%




99.73%

0.13%

0.13%0.00%


Normal State

Alert State


99.87%

0.00%

0.13%0.00%


Normal State

Alert State


100.00%

0.00%0.00%

0.00%


Substation

Normal State

Alert State


96.77%

0.00%

0.00%3.23%


Normal State

Alert State

Emergency State

Blackout/Other 96.77%

0.00%

0.00%3.23%


Normal State

Alert State

Emergency State

Blackout/Other


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2 Alert State 0.00%



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%


Normal State

Alert State

96.64%

0.00%

0.00%

3.36%


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


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.


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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














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)


15 | P a g e

Table: Generation for the month of May, 2018

Graph: Generation for the month of May, 2018

May-18


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


BHP (MW) CHP (MW) THP (MW) KHP (MW) DHP (MW)


16 | P a g e

Table: Generation for the month of June, 2018

Graph: Generation for the month of June, 2018

Jun-18


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


DHP (MW)BHP (MW) CHP (MW) THP (MW) KHP (MW)


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


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


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


20 | P a g e

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)


Substation


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)


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


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



Substation


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)


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


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



Substation


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)


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)


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)


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


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)



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


400kV (Max)400kV (Min)400kV (Ava)220kV (Max)220kV (Min)220kV (Ava)66kV (Max)66kV (Min)66kV (Ava)132kV (Max)132kV (Min)132kV (Ava)


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


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)



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


400kV (Max)400kV (Min)400kV (Ava)220kV (Max)220kV (Min)220kV (Ava)66kV (Max)66kV (Min)66kV (Ava)132kV (Max)132kV (Min)132kV (Ava)


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




operation


(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




operation


(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




operation


(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


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




operation


(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




operation


(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


(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


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



(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



(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


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


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-



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


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-



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


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


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

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

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-


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



(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


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



(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


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




operation


(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




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




operation


(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




operation


(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.


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




operation


(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


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




operation


(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


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




operation


(Line

segment/substation)

Remarks

No Tripping


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


(Line

segment/substation)

Remarks


JigmelingTsi-Jig Line O/C at R &Y Phase 21, Z1/Z1B, 17.4KM Linesegnment


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


operation


(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


General trip,o/c on 3 -

Phases, Zone I, Dist

39.67km towards

Salakati end


lightning


General trip,o/c on B-

Phase, Zone I, Dist

27km towards Salakati

end


lightning


29 | P a g e

June, 2018


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




operation


(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)



Time of

Outage

(Hrs)

Date of

Normalizati

on

Time of Fault

cleared (Hrs)

Duration of

Outages

Load before

Outage

(MW)

Name of Feeders

Tripped




operation


(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


Time of

Outage

(Hrs)

Date of

Normalizati

on

Time of Fault

cleared (Hrs)

Duration of

Outages

Load before

Outage

(MW)

Name of Feeders

Tripped




operation


(Line

segment/substation)

Remarks



Time of

Outage

(Hrs)

Date of

Normalizati

on

Time of Fault

cleared (Hrs)

Duration of

Outages

Load before

Outage

(MW)

Name of Feeders

Tripped




operation


(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



Time of

Outage

(Hrs)

Date of

Normalizati

on

Time of Fault

cleared (Hrs)

Duration of

Outages

Load before

Outage

(MW)

Name of Feeders

Tripped




operation


(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



Time of

Outage

(Hrs)

Date of

Normalizati

on

Time of Fault

cleared (Hrs)

Duration of

Outages

Load before

Outage

(MW)

Name of Feeders

Tripped




operation


(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


operation


(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


main1 optd, RYB phase

tripped main2 optd,

RYB phase tripped

Main1 =11.77km

main2 = 12kmTransient fault


main1 optd, RYB phase

tripped main2 optd,

RYB phase tripped

Main1= 15.2km

Main2= 15.82kmTransient fault


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


operation


(Line

segment/substation)

Remarks


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


30 | P a g e


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


operation


(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


operation


(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-


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


Phase-ABC, Over

Voltage,Fault


trip

time:80.85ms,System


00,IB-00A,IC-00A,VAN-

82.82KV,VBN-

85.61KV,VCN-85.39kV.

132kV Tingtibi-

Nanglam feeder Line


Yourmoo feeder

132kV Tingtibi-

Yourmoo LineTempoary Fault

(Distance relay ) :Trip-

ABC,Fault


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-



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


805.4,IB-830.9A,IC-

824.4A,VAN-

12.46KV,VBN-

12.87KV,VCN-11.38kV.

132kV Tingtibi-


6 13/6/2018 22:06Hrs 13/6/2018 22:13 Hrs 0;07 30.560132kV Tingtibi-

Jigmeling feeder

132kV Tingtibi-


(Distance relay )

:Active Group-I,Start

Phase:ABCN,Trip


I, Fault


t


trip

time:80.18ms,System


827A,IB-828.5A,IC-

822.1A,VAN-

13.51KV,VBN-

14.33KV,VCN-13.23kV.

132kV Tingtibi-



Jigmeling feeder

132kV Tingtibi-


(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


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-


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


t


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


Jigmeling feeder

132kV Tingtibi-



Phase-ABC,Start

Phase:ABCN,Trip


I, Fault


t


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-


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


operation


(Line

segment/substation)

Remarks

No tripping


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



(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


50N-TRIP Trip Values:

I1=360.67A<31.33deg,

I2=37.76A<-87deg,

I3=1969.46A<66.08deg,

I4=360.67A<31.33deg

Line


IV


IV

Tripped due to

trasient fault


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



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



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.


IV


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


II


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



(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.


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


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



(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



(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


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


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



(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


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).



ITransient

1. O/C relay (R & B phase).


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



(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.


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.


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.


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


operation



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


operation



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


operation



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


operation



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


operation



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


operation



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


operation



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


operation



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


34 | P a g e

May, 2018


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



(Line

segment/substation)

Remarks

1 01.05.2018 15:36 01.05.2018 15:41 0:05 3350/63MVA Trasformer -

III


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)


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


ITrip - Substation

6 07.05.2018 17:53 07.05.2018 19:22 0:29 3650/63MVA Trasformer -

III


III Trip - Substation


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



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 -



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



18 23.05.2018 2:55 23.05.2018 3:26 0:31 11220kV Malbase -

Samtse Feeder.

220kV Malbase -



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 -



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



21 23.05.2018 6:03 23.05.2018 6:30 0:27 11220kV Malbase -

Samtse Feeder.

220kV Malbase -


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



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.


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



(Line

segment/substation)

Remarks

No Tripping


35 | P a g e


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



(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


8 23.05.2018 4:05 23.05.2018 6:05 2:00 8.63 66KV Pling-Gomtu Nil Temporary 86 &186 Line




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



(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


6 07.05.2018 21:50 07.05.2018 22:00 0:10 12.566kV Incomer


7 07.05.2018 22:03 07.05.2018 23:20 0:17 12.566kV Incomer


8 08.05.2018 0:05 08.05.2018 1:17 1:12 1.3566kV Incomer


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.


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



(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.


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



(Line

segment/substation)

Remarks


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


II

Transformer got

tripped due to fault

on 33kV

Gurungdara fdr II.


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


II

Transformer got


on 33kV

Gurungdara fdr II.




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


II

Transformer got


on 33kV

Gurungdara fdr II.




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.


36 | P a g e


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


operation




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


operation



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


operation




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


operation



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


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.


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


operation



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


operation



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


operation



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


operation



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


operation



No Tripping

No Tripping

No Tripping

No Tripping

No Tripping

No Tripping

No Tripping

No Tripping


37 | P a g e

June, 2018


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



(Line

segment/substation)

Remarks


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.


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


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


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.


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



(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.


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



(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


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



(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.


38 | P a g e


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



(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


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



(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


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


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


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



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



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._ _ _


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



1 8/6/2018 13:42 8/6/2018 13:43 0:01 4.2 20MVA TR.IOlakha S/S & all

outgoing feeders


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 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.


outgoing feeders


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 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.


outgoing feeders


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.


outgoing feeders


of DPH II







Pick up. 3. Y phase over current Pick

up


tripping.


outgoing feeders


of DPH II







Pick up. 3.


tripping.


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



No Tripping

bhutan power corporation...

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