This document provides information about the construction, components, testing, operation, protection and maintenance of a 132kV switchyard. It includes details about the bus bars, circuit breakers, current transformers, potential transformers, wave traps, isolators, control and protection schemes. The key components of the switchyard are described along with their ratings and testing procedures. The operational modes and protection philosophy are also summarized.

1. 1
BLA Power Pvt. Ltd

2. 2

3. DEFINATION
• A switchyard is a part of an electrical Generation, Transmission,
and Distribution system. Substations transform voltage from high to
low, or the reverse, or perform any of several other important
functions.
• Switchyards generally have Breakers, Isolators , CTs ,PTs , Bus bars,
protection and control equipments, transformers ,grounding wires
and switches, disconnects and metering devices, etc.
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4. 132 KV Switchyard
• Constructional Overview
• Testing
• Operation & Maintenance
• Protection
• Conclusion
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5. Constructional Overview
• Two main Bus-1& 2 bars – ACSR TWIN MOOSE Conductor.
Both are used to energize any abnormality with Bus-coupler for un
interruption Operation.
• Current rating 2000A,Fault Level 40KA for 3 Sec.
• Bay Equipment to Equipment Connection-ACSR Moose
Conductor.
• CTs are connected in Series , PTs are connected across supply.
• STG Generator Transformer Bay -01 No.
• Start-up S.A.T. Bay -01 No.
• 132 KV overhead line circuit Bay -02 No.s
• 132 KV Transfer Bus coupler Bay - 01 No.s
• Fully Equipped Bus PT Bay -02 No.s
5

6. 6
GEN. TRFO. BAY
TRNSFER BUS
COUPLER BAY
BUS PT
O/G OHL #1 BAY
STN. TRFO. BAY
O/G OHL # 2 BAY

7. • Total no. of Towers- 28 (A/B/C/D/E)
• Total no. of SF6 CB- 5
• Total no. of PT-12
• Total no. of CT-12
• Total no. of LA-12
• Total no. of Wave Trap -2
• Total no. of Isolators- 22
• Total no. of CVT- 6
• Total no. of BPI- 18
• Total no. of EMPT -6 7
Constructional Overview

8. 8
GEN BAY SAT BAY

9. 9
B/C BAY
Line# 1 & 2
BAY

10. 10
Bus Bar
Protection Scheme

11. • Rated Voltage 145 KV
• Rated Current 1250 A Frequency 50 Hz
• Breaking Capacity 40 KA
• Making Capacity 100 KVP
• Short Time Rating 40 KA for 3 sec
• Operating sequence
O-0.3 sec - CO- 3 MIN- CO
• Trip and Closing Coil Voltage 110V DC
• Motor Supply 240 V
11
These are used to operate on the fault on line or X-mer depending upon where it is
connected. This isolates the faulty line or equipments from the live portion of the sub
station by opening automatically through protective relays; control cables etc. in
definite time.
Testing for SF6:-
Applied Volt 5KV DC
•IR Value
> 20 GΩ CB ON
[R(Y+B+E),Y(R+B+E),B(R+Y+E)]
> 50 GΩ CB OFF
[R-R’,Y-Y’,B-B’]
•Applied current 100 A DC
Contact Resistance test: R-ø ,Y-ø B-ø < 34 μΩ
•SF6 Gas pressure setting 5.4 bar.
•Breaker , Closing Time 72 ms
Opening Time -29 ms Each Phase

12. 12
Make CGL
Type Outdoor
No of Core 2 Core
Ratio 400-800/1-1A
Class 0.25/0.25
Burden 30 VA
ISF <= 5
Make CGL
No of Core 2
Ratio 132KV/√3/110V/√3/110V/√3
Class 0.2/3P
Burden 100 VA/100 VA
a) Measurement of voltage
b) Provide secondary voltage for
protection.
a) Measurement of current
b) Protection current circuits when currents
passed through protective relays like
Distance protection, Backup protection.

13. Common Testing's Required for CT & PT:-
•IR Test :
Applied Volt 5KV DC
> 10 GΩ [Prim – Earth, Prim – Core]
Applied Volt 1KV DC
> 500 MΩ [Core-Earth]
•Winding Resistance Test:
< 5-6 Ω [Ex: R-ø ,1s1-1s2,1s1-1s3]
•Ratio Test :
[Prim current 400-800]/ [Sec. current 1-1A]
[Ex: R-ø ,1s1-1s2,2s1-2s2]
•Polarity Test :
[Ex: R-ø ,1s1-1s2,2s1-2s2]
•Knee voltage Test:
[Only For Protection Class CT ]
is significance of saturation level of a current
transformer core mainly used for protection
purposes. The sinusoidal voltage of rated
frequency is applied to the secondary
terminals of CT, with other winding being
open circuited which increased by10%, cause
the exiting current to increase by 50%. NEXT
Press

14. 14
P1 P2
S1 S2
Battery 9V
Press Back
•Polarity Test :

15. Make
OBLUM ELECTRICAL
Type METAL OXIDE
LD DISCHARGE CLASS Class-3
Rated Voltage 60 KV
Rated Frequency 48-62 HZ
Maximum continuous Operating
Voltage
102 KV
Nominal Discharge Current 10 KA
MFD 2010
Make
OBLUM ELECTRICAL
 Wave trap is an instrument of Low pass
filter, when power frequency currents are
passed to switchyard & high freq. signals are
blocked. Line trap also is known as Wave trap.
 Shapes like a DRUM.
Use for Carrier Communication (PLCC)
systems for communication among various
substations without dependence on the telecom
company network located in substation control
room (through coupling capacitor and LMU).
To discharge the switching & lighting
voltage surges to earth to protect instrument
in the station. These are high pass filters (50
KHZ to 500 KHZ) pass carrier.
15

16. 16
Make CGL
No of Core 3
Ratio 132KV/√3/110V/√3/110V/√3/110V
Class 0.2/3P/3P
Burden 100 VA/100 VA/100VA
> CVT is a transformer used to step down extra
high volt. Signals & provide low volt. Signals
either for measurement or to operate protective
relays. CVTs are typically 1-ø devices where
stack of capacitors are connected in series
result voltage drop.
Make S & S POWER SWITCHGEAR
EQUIPMENT LTD.
Type Drive Motor/Manual,415 v,3ø
Rated Voltage 145 kv
Rated Current 1250 A
Frequency 50 Hz
Short Time Rating 100 KA for 3 sec
Lightning Impulse with stand
Across voltage
650 kv
> Isolators are used to isolate the high Volt.
from flow through the line into the Bus. It
allows only needed voltage and rest is earthed
by itself if required.
Bushing

17. 17
•Bus: is a line in which the incoming feeder
come into & get into the instruments for
further step up or step down.
•Double line in the bus so that if any fault
occurs in one the other can still have the
current and the supply will not stop.
•Two lines are separated by a little distance by
a conductor [spacer] having a connector
between them .
Spacer
Clamp
Tension
Suspension

18. OPERATIONAL MODES
• Normal Operation :
Synchronization
Start Up / Import
• Inter -Transfer Mode Operation:
Inter Transfer Mode
By Pass change over Scheme:
18
Press
Press
Move Next
Press
Press

19. G
19
DS-1 DS-2
CB
CB
DS-4
DS-3 DS-2
CB
DS-4
DS-3DS-1
DS-2
CB
DS-3
DS-4
DS-1 DS-2
CB
DS-4
DS-1
DS-3
OUTGOING OHL #2 BAYOUTGOING OHL #1 BAY
BUS COUPLER CUM
TRNSFER BREAKER
MAIN -1 BUS
MAIN -2 CUM TRANSFER BUS <--- GT BAY  <--- STN. TRFO BAY 
GENERATOR
G. TRFO
STN. TRFO
DS-5 DS-5
U.A.TRFO
DS-1 DS-2
Gen CB
LOAD

20. G
20
DS-1 DS-2
CB
CB
DS-4
DS-3 DS-2
CB
DS-4
DS-3DS-1
DS-2
CB
DS-3
DS-4
DS-1 DS-2
CB
DS-4
DS-1
DS-3
OUTGOING OHL #2 BAYOUTGOING OHL #1 BAY
BUS COUPLER CUM
TRNSFER BREAKER
MAIN -1 BUS
MAIN -2 CUM TRANSFER BUS <--- GT BAY  <--- STN. TRFO BAY 
GENERATOR
G. TRFO
STN. TRFO
DS-5 DS-5
U.A.TRFO
DS-1 DS-2
LOADLOAD
Press Back

21. G
21
DS-1 DS-2
CB
CB
DS-4
DS-3 DS-2
CB
DS-4
DS-3DS-1
DS-2
CB
DS-3
DS-4
DS-1 DS-2
CB
DS-4
DS-1
DS-3
OUTGOING OHL #2 BAYOUTGOING OHL #1 BAY
BUS COUPLER CUM
TRNSFER BREAKER
MAIN -1 BUS
MAIN -2 CUM TRANSFER BUS <--- GT BAY  <--- STN. TRFO BAY 
GENERATOR
G. TRFO
STN. TRFO
DS-5 DS-5
U.A.TRFO
DS-1 DS-2
LOADLOAD
Press Back

22. 22
CB
DS-2
CB
DS-4
DS-3DS-1
BUS COUPLER CUM
TRNSFER BREAKERS
MAIN -1 BUS
MAIN -2 CUM TRANSFER BUS
DS-1 DS-2
Tripping Prt.
OUTGOING OHL #1 BAY
1. Close DS-3
2. Open DS-3 & DS4
Close DS-3
Tripping Prt.

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CB
DS-2
CB
DS-4
DS-3
DS-1
BUS COUPLER CUM
TRNSFER BREAKER
MAIN -1 BUS
MAIN -2 CUM TRANSFER BUS
DS-1 DS-2
Press Back
Tripping Prt.
OUTGOING OHL #1 BAY

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CB
DS-2
CB
DS-4
DS-3DS-1
BUS COUPLER CUM
TRNSFER BREAKERS
MAIN -1 BUS
MAIN -2 CUM TRANSFER BUS
DS-1 DS-2
Tripping Prt.
OUTGOING OHL #1 BAY
1. Open DS-1
2. Close DS-1
Tripping Prt.
Protection
Tripping fuse Out
Press Back

25. Maintenance
• CTs, PTs ,all auxiliaries terminal tightness.
• SF6 Breaker Gas pressure monitoring &
maintain.
• Stone,metnal layer maintain across the area.
• Monitoring & diagnosis using Hotspot detector
or temperature scanner .
• Isolator & contact cleaning on scheduled.
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26. Thermal Sensor / Hot Spot Detector
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27. 27

28. Protection
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30. 30

31. Protection System
• A series of devices whose main purpose is to
protect persons and primary electric power
equipment from the effects of faults.

32. Why A System Needs Protection?
• There is no ‘fault free’ system.
• It is neither practical nor economical to build a ‘fault free’
system.
• Electrical system shall tolerate certain degree of faults.
• Usually faults are caused by breakdown of insulation due to
various reasons: Short Circuit, High Voltage, system aging,
lighting, etc.

33. Protection System Elements
• Protective relays
• Circuit breakers
• Current and voltage transducers
• Communications channels
• DC supply system
• Control cables

34. Three-Phase Diagram of the Protection scheme
CTs
VTs
Relay
CB
Control
Protected
Equipment

35. How Do Relays Detect Faults?
• When a fault takes place, the
current, voltage, frequency, and other electrical variables
behave in a peculiar way. For example:
– Current suddenly increases
– Voltage suddenly decreases
• Relays can measure the currents and the voltages and
detect that there is an overcurrent, or an undervoltage, or
a combination of both
• Many other detection principles determine the design of
protective relays

36. Main Protection Requirements
• Reliability
• Selectivity
• Speed
• Sensitivity

37. Typical Short-Circuit Type Distribution
Single-Phase-Ground: 70–80%
Phase-Phase-Ground: 17–10%
Phase-Phase: 10–08%
Three-Phase: 03–02%

38. Following type of Protection Curve
used in our plant
1. INSTANTANEOUS/High Speed
2. DMT: (Definite Mean Time-I>>/high set)
3. IDMT: (Inverse Definite Minimum Time)
a. SI - Standard Inverse (I>)
b. VI - Very Inverse
c. EI - Extreme Inverse
d. LTI - Long Time Inverse

39. Formula for Relay Operating Time
calculation
Operating Time:
= A X TMS
Ir C - 1
o A=0.14 & C=0.02 for SI
o A=0.13.5 & C=1.0 for VI
o A= 80 & C= 2.0 for EI
o A=120 & C=1.0 for LTI
o Ir= I(multiple of fault current) / Iset

40. Example:
• If FLC=100A, % setting =105,
• Operate time = 10sec Then TMS=?
If CTR =150/1A, In=150, Isec=1A
As per CTR % set= 0.7*In.
Relay Iset= 700mA, Ir=1.05/1.0=1.05
=>TMS will be 0.136

41. IDMT:SI

42. IDMT:

43. Basic Requirement for Relay Setting
• Equipment Full Rating(V, Amp, Z)
• CT/PT Ratio installed on that feeder
• Identification of CT/PT for Particular
protection.
• Breaker opening & tripping time.
• Equipments Factory Test report/Curve

44. Relay Setting Adopted for our system:
1. OC: 105% to 120% - SI,
2. EF: 10% to 30%. - SI
3. OV: 110%, U/V: 80% - DMT
4. SEF: more than EF and time >0.8to1.0sc.
5. REF/Diff : 08 to12% -Inst.
6. DPR (Z1-inst. Z2-300ms, Z-800ms)

45. Protection used for different System
• For Transmission Line :
a. Distance Protection
b. Backup Direction OC/EF
c. Lightning Protection
• For Transformer:
a. Differential Protection
b. Overfluxing
c. O/C & E/F
d. Restricted E/F

46. e.Sensitive or standby E/F
f. Buchholz
g. Pressure Release Valve
h. Winding/ oil Temperature & LA
• For LT Motor (up to 35KW)
a. Thermal Overload
b. Fuse
• For LT Motor (Above 35KW)
a. Thermal Over Laod
b. O/C & E/F

47. • For HT Motors:
a. Thermal Over Load
b. O/C & E/F
c. Locked Rotor
d. Negative Phase Sequence
e. Start supervision
f. Restart Inhabit
• For Generator :
a. Differential Protection
b. Stator Earth Fault (100% & 90 %)

48. c. Rotor E/F
d. NPS
e. Backup Impedance
f. Backup O/C & E/F
g. Loss of field
h. Reverse Power (Short Time /Long time)
i. Thermal Overload Alarm
j. Dead Machine
k. Winding temperature
l. O/V & U/V

49. .

50. SUMMARY
• The Operative Direction for Directional OC Relays are as follows:
– GT bay relay is having operative direction towards GT.
– Line bay relay is having operative direction towards Line.
– Station Transformer. Relay is having operative direction towards Station Transformer.
• Grading margin of 0.3 seconds has been considered between different levels of
protective devices.
• In case of a fault on Line, Distance relay will operate instantaneously. If it fails to
Operate than Directional OC relay will operate as backup.
• If the fault is still found persisting than GT bay and other line bay relay will give
further backup and will trip their respective breakers to clear the fault.
• In case of a fault on Bus, Bus differential relay will operate instantaneously. If this
relay fails to clear the fault , all other feeders including two line bays and GT bay
relays will trip their respective breakers to clear the fault .
• In case of a fault in Generator Transformer (GT),Differential protection for GT will
operate instantaneously. And Directional relay looking towards GT will give backup to
it. If the fault is still found persisting than all other feeders including two line bays will
trip their respective breaker to clear the fault.

51. Forward Path
• For Trouble Free Operation.
• Longevity of System.
• 2 No.s Upcoming Bays for Unit-II
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52. Special Thanks
• for Guidance
Mr. U.P. Sharma
Sr. Manager [ Dept. Of Electrical ]
• for Co-ordination
Mr. Nilesh Malviya
Mr. Dhanajya Ray
Engineer [ Dept. Of Electrical ]
52