Substation Components
Substation Components
Substation Components
by
P.K.PATTANAIK
07/11/14 P.K.PATTANAIK 1
House Keeping ……
1. Introduction
2. Acquaintance to Sub- Station Equipments
i. Working Principle
ii. Significance to Protection Scheme
iii.Name plate Study
iv.Updated technology in present Practice
3. Sub-Station Lay out/ Electrical Concepts
4. OPEN SESSION
5. Conclusion
DC -
SECONDARY
PROTECTION
DC +
SUB STATION MAIN EQUIPMENTS
Equipments Functions
Lightning Arrester Discharges the lightning and switching surge Voltage
to Earth
Wave trap Traps the high frequency signals to the system
equipments
Isolator Air dis-connection of circuit for safety maintenance
Earth Switch Discharges voltage on Dead line
Circuit Breaker Auto disconnection of circuit for fault or abnormal
condition
Current Transforms current from High to Low for control and
Transformer protection circuit
Potential Transforms voltage from High to Low for control and
Transformer protection circuit
Lightning Arrester
Surge Arrestor / Lightning Arrestor
Make/Model
1. MCOV :- Maximum Continuous
Sl No / Year
Mounting Suspension
Make Type
Rated Normal 3150 A Rated Duration of short Circuit current 31.5 KA , 3 Sec
Current
Rated Opening 220V DC Rated Voltage and frequency for Aux. 415 VAC , 50 HZ
Voltage Circuit
Month / Year of
Manufacturing
Circuit Breaker Name Plate Study
Rated Lightning withstand voltage:- Peak value of standard voltage surge 1.2/50 μs that the
insulation of a device can withstand. The meaning of this is “ in 1.2 micro second the voltage reaches its
peak value and in 50 micro second it decays to the half of this value
1st pole to clear factor:- For 3 phase circuit breakers, arc extinction in 3 pole does not become
simultaneous, for which the recovery voltage of the pole, first to extinguish the arc is of the order of
1.2 to 1.5 times the phase voltage and called First Pole to Clear Factor and defined as the ratio of the
Voltage between the (healthy phase and faulty phase) to (Normal phase voltage)
Operating cycle :- The possible operational sequence of the breaker between the close and
opening operation is called Operating cycle . This information is important for the choice of the
breaker whether suitable for auto reclosing system or not. General operating cycle is as ( O-10s-CO-
3min-CO for normal operation and O-0.3s-CO-3min-CO for auto re-close condition
Short-time Current Rating:- The circuit breaker must be capable of carrying short-circuit
current for a short period while another circuit breaker (in series) is clearing the fault. The rated
short-time current is the rms value (total current, both A.C and D.C components) of the current
that the circuit breaker can carry safely for a specified short period
Transient Recovery Voltage (TRV) or Re-striking voltage:-For the AC circuit breaker , for
the case of current interruption even after current becoming zero, certain voltage appears across the
contacts, which is transient in nature and called TRV or Re-striking Voltage.
Instrument Transformer ( CT, PT)
Current Transformer Principle
Current sensor
I2
I1
Voltage Transformer
Principle Voltage sensor
Magnetic circuit (core)
Primary
Windings Secondary
Windings
U1 U2
CVT Principle
OUT DOOR S/S CTs (Live Tank CT)
Dead Tank CT U Shape Live Tank CT
Voltage Transformer CVT
Oil expansion device
Capacitor elements
Capacitor column
Insulating oil
Insulator flange
Inductance
MV Transformer
Damping circuit
Combined CT and PT unit
Optic Fiber CT
Current Transformer Principle
CT NAME PLATE STUDY
Particulars Rating / Value Particulars Rating / Value
Make Type
Sl. No/YEAR
P1 C2
C1
P2
S1 S2 S3
CT NAME PLATE STUDY
RATIO 400-200-100/1-1-1-1-1
PRI/SEC CURRENT (A) 400/1 200/1 100/1
PRI. CONN. P1C1– P2C2 C1-C2 C1-C2
SEC. CONN.
CORE 1 1S1-1S3 1S1-1S3 1S1-1S2
CORE2 2S1-2S3 2S1-2S3 2S1-2S2
CORE3 3S1-3S3,S’ 3S1-3S3,S’ 3S1-3S2,S’
CORE4 4S1-4S3 4S1-4S3 4S1-4S2
CORE5 5S1-5S3 5S1-5S3 5S1-5S2
CORE 1 2 3 4 5
OUT PUT* - - 40 - -
ACC. CLASS* PS PS 0.5 PS PS
ISF/ALF* - - ≤5 - -
Vk (V) Min* 1200 1200 - 1200 1200
I exc@Vk *(mA) Max * 25 25 - 25 25
Rct at 75 0 C Max* 5 5 - 5 5
* AT 400/1 AND 200/1 RATIO ONLY
CVT NAME PLATE STYUDY
Particulars Rating / Value Particulars Rating / Value
110/√3 V 3a-3n 50 3P
CT Circuit Connection Principle
Polarity and connection.
Star connection circuit
IR = I , angle( 0 ) R
IY = I, angle (-120)
IB = I, angle (120)
IR+ IY+ IB= IN R
y
B
Application of Instrument Transformers
ELECTRICAL PROTECTION SYSTEM
DC -
SECONDARY
PROTECTION
DC +
FAULT OUTSIDE Differential ZONE
2400 A 4800A
600/1 A 1200/1A
0A
4A 4A
132Kv
66Kv
FAULT INSIDE DIFFERENTIAL ZONE
2400 A 4800A
600/1A 1200/1A
8A
4A 4A
132KV 66Kv
PROTECTION PHILOSOPHY ( WHY)
Protection System
CT Circuit Breaker
Circuit
Protection Breaker
VT Trip
Equipment Mecha-
Coil
nism
TE
DC-System
1. What is Relay?
A device which detect intolerable or unwanted
conditions within the assigned area.
A watchman or watchdog for the equipment/area
Silent sentinels to power system.
Setting groups
Programmable logic
Adaptive schemes
Communication capability
Instrumentation features
ADDITIONAL FEATURES
State-of-the-art-technology
Simple design
Operational flexibility
Low relay burden
Reduction of panel size & wiring
Reduced commissioning time
Reduced testing time
Fault disturbance recording & analysis
Sequence of events recording
PROTECTION SYSTEM
Generator T/F Protection 220 KV LINE
protection
BUS
LBB
132KV
BUS 132/11KV
T/F
Line protection
132 KV D/C
TR. LINE
11KV
BUS
Bus Bar
Protn.
Generation Evacuation
GENERATOR PROTECTION
Field Failure
GEN. DIFF.
Reverse
Power
Differential
element
400/1 1200/1
100MVA , 220/66 KV
262.5A 875A
00 00
Yy0
400/1 1200/1
Over fluxing
Buchholz, WT, OT, & PRV alarm / trip
BUS FAULT
BUS BAR PROTECTION
BUS-1
BUS-2
BUS BAR PROTECTION
ZONE-1
BUS BAR PROTECTION
ZONE-1
ZONE-2
LINE PROTECTION Z3
Z2
Z1
X X X X
X X
Z1
Z3 Z2
X X
X X
X X
A B C D
IED ( Intelligent Electronics Device)
Event Logger
Disturbance recorder
Fault Locator
Numerical relays