Download - Oc Relay Ion
-
7/29/2019 Oc Relay Ion
1/47
Basic Information
O/C E/F Relay & Time Coordination1
O/C E/F Relay &Time Coordination
Basic
Information
-
7/29/2019 Oc Relay Ion
2/47
O/C E/F Relay & Time Coordination2
General Circuit Diagram200/1 Amp
R Ph O/C (51R)
E/F (51N)
B Ph O/C (51B)
150 Amp
150 Amp
150 Amp
0.75 Amp
0.75 Amp
0.75 Amp
0.0 Amp
C11
C31
C51
C71
S1
S1
S1
S2
P1 P2
-
7/29/2019 Oc Relay Ion
3/47
O/C E/F Relay & Time Coordination3
1S1R
1S2R
1S3R
1S1Y
1S2Y
1S3Y1S1B
1S2B
1S3B
2S1R
2S2R
2S3R
2S1Y2S2Y
2S3Y
2S1B
2S2B
2S3B
3S1R
3S2R3S3R
3S1Y
3S2Y
3S3Y
3S1B
3S2B
3S3B
R Ph CT
Y Ph CT
B Ph CT
Core-1Core-2Core-3
Core-1Core-2Core-3
Core-1Core-2Core-3
A11
A31
A51
A71
C11
C31
C51
C71
D71
D11
D31
D51
Yard MB Wiring
-
7/29/2019 Oc Relay Ion
4/47
O/C E/F Relay & Time Coordination4
1S1R
1S2R
1S3R
1S1Y
1S2Y
1S3Y1S1B
1S2B
1S3B
2S1R
2S2R
2S3R
2S1Y2S2Y
2S3Y
2S1B
2S2B
2S3B
3S1R
3S2R3S3R
3S1Y
3S2Y
3S3Y
3S1B
3S2B
3S3B
R Ph CT
Y Ph CT
B Ph CT
Core-1Core-2Core-3
Core-1Core-2Core-3
Core-1Core-2Core-3
A11
A31
A51
A71
C11
C31
C51
C71
D71
D11
D31
D51
Yard MB Wiring
-
7/29/2019 Oc Relay Ion
5/47
-
7/29/2019 Oc Relay Ion
6/47
O/C E/F Relay & Time Coordination6
Single Line to Ground Fault200/1 Amp
R Ph O/C (51R)
E/F (51N)
B Ph O/C (51B)
1500 Amp
7.5 Amp
7.5 Amp
C11
C31
C51
C71
S1
S1
S1
S2
P1 P2
-
7/29/2019 Oc Relay Ion
7/47
O/C E/F Relay & Time Coordination7
Electromagnetic Induction relays
50%75%
100%125%150%
200%
1 2
-
7/29/2019 Oc Relay Ion
8/47
Relay Operation Time - 1
O/C E/F Relay & Time Coordination8
E/F PSM 30% i.e. 0.3 Amp
E/F Relay Current 7.5 AmpE/F Relay Current is 7.5/0.3 = 25 Times
its operating current
From Graph for 25 Times relay operating
current for TMS = 0.15 relay time of
operation would be @ 0.35 Sec
O/C PSM 100%
O/C Relay Current 7.5 Amp
It is 7.5 times relay operating current
From graph for 7.5 Times relay operating
current and for TMS = 0.1 time of
operation for the relay would be 0.35 Sec
( Zoom out Graph)
http://localhost/var/www/apps/conversion/tmp/scratch_1/IEC-A%20Normal%20Inverse%20jpeg.jpghttp://localhost/var/www/apps/conversion/tmp/scratch_1/IEC-A%20Normal%20Inverse%20jpeg.jpg -
7/29/2019 Oc Relay Ion
9/47
Relay Operation Time - 2
O/C E/F Relay & Time Coordination9
Actually our problem is to decide relay settings and not relay time of
operations as shown previously
Hence Unknowns are
Relay PSM
Relay TMS
Whereas known facts areRelay placement and purpose of use
Relay current during fault ( i.e. CT secondary current during fault. )
Relay desired time of operation.
General Steps
1) Decide PSM2) Find out fault current
3) Find out multiple of relay set current as per decided PSM in step-1
4) Find out time of operation for above multiple of current and TMS=1 using
relay characteristic curve
5) Decide relay time of operation as per protection needs
6) Find out TMS = Required Time of operation /Time of operation with TMS =1
-
7/29/2019 Oc Relay Ion
10/47
Basic Information Selection of PSM
O/C E/F Relay & Time Coordination10
E/F PSM generally selected as 30% ( Other than 30% settings may also be selected but about this
discussed somewhere else in the presentation)
For O/C PSM is selection depends upon place and purpose of use for example
1.Transformer O/C protection
a) Transformer HV or LV side O/C relay PSM settings should be in commensuration with transformer
full load current and respective CT ratio such that PSM = T/F Full load current / CT ratio ( Generally
expressed in %)
b) For example for a 25 MVA transformer HV side full load current is 109 A if HV CT ratio is 200/1 Amp
then PSM =109/200 55% ( exact value 54.5%)
c) For old type numerical relay it was not possible to go as near as possible to value calculated fromabove formula due to large steps available
d) Under such condition it is decision as per local condition to select higher or lower nearest PSM
e) In above example it is customary to select 50%, however due to this selection there is apparent
loss of about 10% capacity of the T/F
f) It is also possible to select 75% but load on transformer is to be monitored carefully ( and manually
)
2.For 220-132 kV feeder
Here generally it is customary to select relay PSM as per-
a) Line conductor allowable loading limit
b) CT primary normal current
c) Substations capacity/normal load feed by the line
d) Considering above facts it is very common to select 100% PSM for 132kV lines with CT ratio 400/1
Amp
e) For 220kV lines with CT ratio 800/1 amp and conductor 0.4 ACSR or 0.525 AAAC it is 100%
a)For 33-11kV feedera) As per local feeder condition, load pattern and needs ranging between 50% to 100%
-
7/29/2019 Oc Relay Ion
11/47
Relay Operation Time - 3
Desired time of operation will depend upon
a) Equipment being protected
b) Time discrimination from down stream protection (150 ms 250 ms)
c) Time of operation of main protection etc.
For transformer LV side protection it is common to adopt 250 ms asoperating time.
This is so as to have 150 ms time discrimination from 100 ms relay
time of operation for lower (feeder) protection.
When relays are used as backup protection of 132kV lines its time
of operation shall be equal to Z-2 time of operation (300 350 ms). Once these two things decided there remains only mathematical
part
O/C E/F Relay & Time Coordination11
-
7/29/2019 Oc Relay Ion
12/47
-
7/29/2019 Oc Relay Ion
13/47
14
-
7/29/2019 Oc Relay Ion
14/47
Introduction
Fuse wire is simplest protection
Fusing ampere of copper wire of diameter d
expressed in Cm is given by the formula A =
2530*d3/2
Time taken by fuse to blow off depends up onfusing amperes
O/C E/F Relay & Time Coordination14
-
7/29/2019 Oc Relay Ion
15/47
-
7/29/2019 Oc Relay Ion
16/47
-
7/29/2019 Oc Relay Ion
17/47
18
-
7/29/2019 Oc Relay Ion
18/47
Simplest Protection - Fuse
Log scale graph are
use full tool where
range of values varies
very widely
This variation in rangeis generally 10,000
times
It does not affect
overall accuracy of
selecting proper value
manually
O/C E/F Relay & Time Coordination18
O/C / & C19
-
7/29/2019 Oc Relay Ion
19/47
General mathematical formula for timecharacteristic of the relay as per IEC
Standards
K
Time Of Operation = ---------------------
( ( Is/Ib) - 1 )
O/C E/F Relay & Time Coordination19
-
7/29/2019 Oc Relay Ion
20/47
-
7/29/2019 Oc Relay Ion
21/47
O/C E/F R l & Ti C di ti22
-
7/29/2019 Oc Relay Ion
22/47
Use of Log Scale-2
O/C E/F Relay & Time Coordination22
-
7/29/2019 Oc Relay Ion
23/47
O/C E/F R l & Ti C di ti24
-
7/29/2019 Oc Relay Ion
24/47
Use of Log Scale-4
O/C E/F Relay & Time Coordination24
O/C E/F R l & Ti C di ti25
-
7/29/2019 Oc Relay Ion
25/47
Transformer Protection Damage Curve
Damages to the equipment due
to fault current flowing through itare mainly due to heating effect
of the current ( I2Rt)
Hence fuse time characteristic
initially suited very well to the
equipments in the power system
This figure shows protection of
transformer with the help of relay
and breaker
This also indicates how inverse
characteristic of O/C Relay is
suitable to protection of powersystem equipments
( More about Transformer
Damage Curves)
( More about this figure )
O/C E/F Relay & Time Coordination25
http://localhost/var/www/apps/conversion/tmp/scratch_1/LINK-C57.109-1993.pdfhttp://localhost/var/www/apps/conversion/tmp/scratch_1/LINK-C57.109-1993.pdfhttp://localhost/var/www/apps/conversion/tmp/scratch_1/LINK-Guide%20for%20protection.pdfhttp://localhost/var/www/apps/conversion/tmp/scratch_1/LINK-Guide%20for%20protection.pdfhttp://localhost/var/www/apps/conversion/tmp/scratch_1/LINK-C57.109-1993.pdfhttp://localhost/var/www/apps/conversion/tmp/scratch_1/LINK-C57.109-1993.pdf -
7/29/2019 Oc Relay Ion
26/47
O/C E/F Relay & Time Coordination27
-
7/29/2019 Oc Relay Ion
27/47
Protection of Transformer by O/C Relay
O/C E/F Relay & Time Coordination27
Trafo Damage
Curve
Long Time
Inverse
Extremely Inverse
Normal Inverse
O/C E/F Relay & Time Coordination28
-
7/29/2019 Oc Relay Ion
28/47
End of More Information
O/C E/F Relay & Time Coordination8
After understanding basics of relaycharacteristic curves and its selection
according to protection needs we will
turn to allied information about O/C E//Frelaying
This allied information will prove helpful
in overall understanding aboutdevelopment of protective relays and its
use in power system
O/C E/F Relay & Time Coordination29
-
7/29/2019 Oc Relay Ion
29/47
Basic Information
O/C E/F Relay & Time Coordination
O/C E/F Relay &Time Coordination
Allied
Information
O/C E/F Relay & Time Coordination30
-
7/29/2019 Oc Relay Ion
30/47
Disadvantages of fuses
Though simple less accurate ( If Rewirable)
Because of previous heating effect
Ambient Temperature
In consistencies in material
Limitations for breaking capacities hence suitable for LV and to
some extent MV HRC Fuses
More accurate
Higher rupturing capacities
Requires time for replacement
Suitable for LV and to some extent MV
O/C E/F Relay & Time Coordination
O/C E/F Relay & Time Coordination31
-
7/29/2019 Oc Relay Ion
31/47
Early Development of Protective Schemes
This simple device (Fuse) played a veryvital role during early development of
power systems
As the complexity of power system
increased other technique get introduced
like breaker, relay DC battery etc. (How?)
O/C E/F Relay & Time Coordination
O/C E/F Relay & Time Coordination32
http://localhost/var/www/apps/conversion/tmp/scratch_1/LINK-History%20of%20protection.pdfhttp://localhost/var/www/apps/conversion/tmp/scratch_1/LINK-History%20of%20protection.pdf -
7/29/2019 Oc Relay Ion
32/47
Early development of power system
History of power system protection dates back nearly to the start of development of power system
it self
In real sense power system started growing due to invention of incandescent lamp by Edison
during 1880
Edison was promoter of DC power system ( Why ? )
General Electric founded by him was main supplier of electricity in Newyork.
Washington first introduced AC system with the advancement in transformer during 1887
During 1890 charls introduced symmetrical component analysis which helped in analyzing 3 ph.
Power system and there by possible to design larger machines and power systems. Modern day power system came into existence from 1890
One of the patent of fuse is in the name of Edison
Development of relays breakers and instrument transformers took place during 1890 to 1920 and
modern day protection system came into existence.
And during last century development of power system continuous to be there however main
principles of power system protection are 3S and 1R remained same.
Development of relays breakers and instrument transformers took place during 1890 to 1920 andmodern day protection system came into existence.
And during last century development of power system
continuous to be there however main principles of power
system protection are 3S and 1R remained same.
O/C E/F Relay & Time Coordination
O/C E/F Relay & Time Coordination33
-
7/29/2019 Oc Relay Ion
33/47
General Requirements of Protective Scheme
For any protective device following Functional
Characteristic are important.
Sensitive
Selectivity
Speed
Reliability
( Note:- 3 S & 1 R)
As a improvement over simple fuses (in aboveareas) other protective devices get developed
with the advancement of power system
O/C E/F Relay & Time Coordination
O/C E/F Relay & Time Coordination34
http://localhost/var/www/apps/conversion/tmp/scratch_1/LINK-Functional%20Characteristics.jpghttp://localhost/var/www/apps/conversion/tmp/scratch_1/Links/LINK-Functional%20Characteristics.jpghttp://localhost/var/www/apps/conversion/tmp/scratch_1/Links/LINK-Functional%20Characteristics.jpghttp://localhost/var/www/apps/conversion/tmp/scratch_1/LINK-Functional%20Characteristics.jpghttp://localhost/var/www/apps/conversion/tmp/scratch_1/LINK-Functional%20Characteristics.jpghttp://localhost/var/www/apps/conversion/tmp/scratch_1/LINK-Functional%20Characteristics.jpghttp://localhost/var/www/apps/conversion/tmp/scratch_1/LINK-Functional%20Characteristics.jpg -
7/29/2019 Oc Relay Ion
34/47
3S & 1R
Sensitivity is that property of protection system which enables it to
distinguish between fault and no fault condition very correctly. As if we say that some animals are more sensitive than humans to
natural disasters like earthquake.
Where as selectivity is that property of the power system which
enables it to isolate only the faulty part from healthy part.
In this sense differential protection is most selective protection
Once the fault detected by SENSITIVE system and area to bedisconnected detected by SELECTIVE system then there comes the
SPEED.
This faulty section should be get cleared as early as possible.
For EHV system Faults are once in blue moon. Hence this all above
said things should happen RELIABELY even after 5-10 years from
design and commissioning of the protection system.
O/C E/F Relay & Time Coordination
O/C E/F Relay & Time Coordination35
-
7/29/2019 Oc Relay Ion
35/47
O/C E/F Relay & Time Coordination
Changing Trend In Protective Relaying
Protection relay is a tool for
protection engineer
During last 30 years relay
operating principles changed
very drastically
Electromagnetic Relays
Static Relays
Digital Relays
Numerical Relays
Though it is not required to
design a relay or repair a relay
at site it is customary to havesome working knowledge of
these relays for better
understanding and use of it
O/C E/F Relay & Time Coordination36
-
7/29/2019 Oc Relay Ion
36/47
O/C E/F Relay & Time Coordination
Electromagnetic Induction relays
O/C E/F Relay & Time Coordination37
-
7/29/2019 Oc Relay Ion
37/47
O/C E/F Relay & Time Coordination
Static Relays
-
7/29/2019 Oc Relay Ion
38/47
O/C E/F Relay & Time Coordination39
-
7/29/2019 Oc Relay Ion
39/47
O/C E/F Relay & Time Coordination
Numerical Relay
FunctionsAvailableinNum
ericalO/C
Relay
-
7/29/2019 Oc Relay Ion
40/47
O/C E/F Relay & Time Coordination41
-
7/29/2019 Oc Relay Ion
41/47
Introduction
O/C E/F Relay & Time Coordination
R3 R2 R1
A B C
10 sec.25 sec.40 sec.
R3 R2 R1
A B C
200 ms220 ms180 ms
R3 R2 R1
110 ms350 ms500 ms
S
S
S
O/C E/F Relay & Time Coordination42
-
7/29/2019 Oc Relay Ion
42/47
Study of Time Co-ordination and its role in design of protection scheme.
Over Current and Earth Fault Protection is
used for
Protecting a equipment
Selective tripping of faulty section of the
power system
Backing up the main protection
O/C E/F Relay & Time Coordination
O/C E/F Relay & Time Coordination43
-
7/29/2019 Oc Relay Ion
43/47
Role of Over Current Relay in Protecting the Equipment
It is obvious that over current protective system should
act and interrupt the fault current before to damage ofequipment due to fault current through it.
Power system equipments include Line, Isolator, CT,
Breaker, Transformer
Obviously Transformer is most costliest and delicate (forfault currents) equipment first we will consider its
damage curve and decide parameters of protection
system so that it should act fast enough to protect the
transformer This can be ascertained with the help of Damage Curve
of the transformer and time-current curve of the
protective system
O/C E/F Relay & Time Coordination
O/C E/F Relay & Time Coordination44
-
7/29/2019 Oc Relay Ion
44/47
Role of Over Current Protection in Selective Tripping
It is obvious that only that part of the power system
should get disconnected where the fault exists
Hence proper time co-ordination should be there so as to
let the down stream protection should act fast enough
and up-stream protection should give sufficient time for
down stream protection to act
Otherwise un-necessary larger area get affected
O/C E/F Relay & Time Coordination
O/C E/F Relay & Time Coordination45
-
7/29/2019 Oc Relay Ion
45/47
y &
Backup Protection
When ever main protection fails to separate the
faulty section backup protection take up this role As such there is inherent time delay in operation
of backup protection
This backup protection can be employed in main
protection itself as additional function, butinvariably it is employed as a separate relay toensure its operation even if failure ofquantities/links which are common to bothfunctions such as-
DC Source PT supply
Relay hardware
Main CTs
-
7/29/2019 Oc Relay Ion
46/47
O/C E/F Relay & Time Coordination 47
-
7/29/2019 Oc Relay Ion
47/47
y
Backup Relay Time Coordination
A C
E
F
X Y
Z
M