This document provides an overview of an 11kV electrical system, including: 1) The main components of an 11kV electrical system including switchgear, distribution transformers, cables, and auxiliary power supply. 2) Details on the internal arrangement and functioning of 11kV switchgear, circuit breakers, and protection relays. 3) Explanations of temperature monitoring systems, interlocking mechanisms, and the roles of various components in protecting the electrical system.

1. 11kV Electrical System Operational Introduction
Present By : ESTA International Private limited.

2. 11kV Electrical System
AC &DC
Auxiliary Power
Supply
11000/415V
Distribution
Transformer
11kV Power
cable
11kV
Switchgear
Circuit Breaker ACDB
Winding
Earthing switch
24V Battery
charger
Housing
Curr. Tr. & Vol. Tr. Temperature
Monitor 24V Battery
bank
Protection relay
Meters
Indication
2

3. 11kV Electrical System

4. 11kV Switchgear Introduction
Make
Type
Busbar
:
:
:
ABB
Unigear ZS1
Air insulated
Single busbar system.
Circuit Breaker : V
acuum Circuit breaker
ABB - VD4-12.12.25.
Number of panel : 4 Nos

5. Incomer / Outgoing Panel-Internal Arrangement
 Breaker Compartment
 Bus Bar Compartment
 CT & Cable Compartment
 PT Compartment
 LV Compartment
Circuit Breaker
Bus Bar
Earth switch
V
oltage Detecting Insulator
V
oltage Transformer
Current Transformer

6. Circuit Breaker (CB) Introduction
• Mechanical device capable of making,
carrying and breaking currents under
normal and rated fault conditions.
• Provide electrical isolation when open.
Fault Occurs
Circuit Breaker
1. Trip Coil Energizes
2. Operating Mechanism
Starts
3. Circuit Breaker Opens
Relay Senses and
Relay contact
closes
Isolate The Faulty
Part from the
system

7. Parts Of Circuit Breaker Circuit Breaker
1. Lever for manually charging the
closing spring
Indication for circuit-breaker
open/closed
Rating plate
Opening pushbutton
Closing pushbutton
Indication for closing spring
charged/discharged
Operation counter
Connector (plug)
2
3
4
5
6
7
8

8. Parts Of Circuit Breaker Circuit Breaker
1.
2.
3.
Isolating contacts
Truck
Operating lever for circuit-
breaker racking-in/out

9. Incomer Panel - Control Cabinet Equipment.
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
Semaphore indicator
V
oltage Presence Indicator
Indication Lamps.
Annunciator Window.
Master trip relay.
Alarm sounder
AnalogAmmeter
Analog V
oltage meter
Multi Function Meter
Protection Relay
V
oltmeter Selector switch.
Ammeter Selector switch.
Remote-Local Selector Switch
Trip-Neutral-Close Switch
Test Terminal Block

10. Protection System Analogy
Protection Relay
Current Transformer
Voltage Transformer
Circuit Breakers
Hands & Legs
Eyes,Ears,Nose & Skin
Brain

11. Protection Functions In REF 601 relay.
Over Current (IDMT) - 51
Overcurrent (INST) - 50
Earth Fault (IDMT) - 51N
Earth Fault (INST) - 50N
IDMT (Inverse Definite Minimum Time)

12. Protection Relay REF 601.

13. 11kV Electrical system Interlocks
• To prevent damages and accidents
case of mal-operations
Can be electrical, mechanical or
electromechanical or combined
Can be realized via relays, coils or
numerical units
in
•
•
• Interlocking conditions for a HV switching
device depends on switchyard
configuration and status of other
switching devices

14. Electrical system Interlocks – In 11kV switchgear
• The circuit breaker can only be moved from the
test/disconnected position when the circuit
switch are off.
breaker and earthing
• The circuit breaker can only be switched
position.
on
In
when the circuit
breaker is in the test or service the intermediate
position, the circuit breaker is mechanically interlocked.
In the service or test positions, the circuit breaker can only be
switched off manually when no control voltage is applied and it
cannot be closed.
Connecting & disconnecting the control wiring plug is only in the
test/disconnected position of the circuit breaker.
•
•

15. Electrical system Interlocks – In 11kV switchgear
• The earthing switch can be switch on if the circuit breaker is in the
test/disconnected position or outside of the panel
If the earthing switch is on the circuit breaker cannot be moved
from the test/disconnected position to the service position.
The circuit breaker cannot be racked-in if the circuit breaker
compartment door is open.
The circuit breaker compartment door cannot be opened if the
circuit breaker is in service position.
•
•
•
• The compartment door cannot be opened if the earthing switch
open
is
• The earthing switch cannot be operated if the cable compartment
door is open

16. 11kV/415V
, 1500kVATransformer
• Static
transforms
alternating
device which
a system
voltage
of
and
current into
of voltage
another system
and current at
the same frequency
Type Cast coil dry type Transformer
Installation Indoor
Rated High Voltage 11000 V
Rated Low Voltage 415 V
Rated Power 2000/2800 kVA
Phase 3
Frequency 50 Hz
Tapping on HV ± 2 steps X 2.5 % (Off circuit)
Vector group Dyn11
Type of cooling AN/AF
Insulation class (HV/LV) F/F
Conductor Material (HV/LV) C-Copper A-Aluminum C/C

17. Transformer - Internal Arrangement

18. Temperature sensors
• Each
has
of
one
the coils in the transformer
pt100 temperature sensor
fitted inside it.
If the coil temperature reaches Alarm
•
temperature, the transformer load
must be reduced.
• If the coil temperature reaches Trip
temperature, the
be shut down.
transformer must

19. Transformer – Temperature Monitor
Class Alarm temperature Trip temperature
F 140 °C 155 °C
H 160 °C 175 °C
FAN MAN Activate cooling fan manually
Guard Setting (o
C)
Fan on 70
Fan off 60
Temp Alarm 90
Temp trip 110
TRIP Transformer Temp. High Trip activated
ALARM Transformer Temp. High Alarm activated
FAN Transformer cooling activated
FAULT Temperature monitor internal fault
T-MAX Maximumtemperature
SCAN Chanal 1-2-3-4 scanning( 2 sec)
AUTO Automatic hottest scanning
MAN Manual scanning

20. Auxiliary Power
Don’t
Let
Them
off.
 24 V DC
• For Protection & Control.
 230 VAC
• Spring charging motor.
• Space heaters.
• Control Cabinet light.
• Socket outlet.

21. Auxiliary Power 24 V DC

22. On Site Training
Identifying the parts of 11kV electrical system.
Taking meter readings.
Fault alarm and trip indication identification and resetting.

23. Thank you
Present By : ESTA International Private limited.