This document contains a presentation given by G Ravindra Kumar about his full semester internship training at GMR Kamalanga Energy Limited. The presentation discusses different types of switchgear including low voltage, medium voltage, and high voltage switchgear. It describes components of switchgear like circuit breakers, relays, current transformers, and details the operating principles and advantages of vacuum and air circuit breakers. Load details of various units of 6.6kV switchgear are also presented.

1. GMR Institute of Technology
An Autonomous Institute Affiliated to JNTUK Kakinada.
Full semester Internship 1st Presentation
Dept. Of Electrical and Electronics Engineering

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Title
FULL SEMESTER INTERNSHIP TRAINING
AT
GMR KAMALANGA ENERGY LIMITED
Topic:
HT and LT SWITCHGEAR
PREPARED BY:
G Ravindra Kumar
(14341A0233)
Under the esteemed guidance of
Debasis Das and Somanath Patra
2

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Switchgear:
It is defined as the apparatus used for Switching, Controlling and Protecting the
Electrical Circuits and equipment.
In general, Switchgear is used for two purposes
• Switching during normal operating conditions for the purpose of Operation
and Maintenance.
• Switching during Faults and Abnormal conditions and interrupting the fault
currents.
3

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Depending on the voltage level, switch gear is classified into 3 types
 Low Voltage Switchgear/LT Switchgear (<1KV)
 Medium Voltage Switchgear/MV Switchgear (<33KV)
 High Voltage Switchgear/HT Switchgear(>33KV)
But in heavily polluted areas Indoor Switchgear are preferred even for high
voltages
Scheme of switchgear bus
a) 2 incomers & 1 bus coupler
b) Bus coupler can be manual or auto changeover

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Components of Switchgear:
 Circuit Breaker
 Relay
 Current Transformer
 Capacitor Voltage Transformer
 Terminal Box
 Switches
 Fuse
 Energy Meter

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WHAT IS A CIRCUIT BREAKER?
A circuit breaker is an equipment that make or breaks a circuit either manually or
automatically under all conditions at no load, full load or short circuit.
Operating Principle
Two contacts called electrode remains closed under normal operating conditions.
When fault occurs on any part of the system, the trip coil of the circuit breaker
get energized and contacts are separated
The Circuit breaker used are:
 Air Circuit Breaker
 Vacuum Circuit Breaker
 Moulded Case Circuit Breaker

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Vacuum Circuit Breaker
Advantages
• Compact, reliable and have
longer life.
• No fire hazards.
• No generation of gas during
and after operation.
• Can interrupt any fault current.
• No noise is produced while
operating.
• Require less power for control
operation.

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Vacuum Circuit Breaker
Vacuum ChamberInside the Vacuum Circuit Breaker

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Air Circuit Breaker
• Circuit breaker shall be three pole, single
throw, air break type.
• Circuit breakers shall be draw out type,
having SERVICE, TEST & ISOLATED
positions with indication for each
position.
• Each breaker shall be provided with an
emergency manual trip, mechanical ON-
OFF indicator mechanism,
charge/discharge indicator.
• Mechanical safety interlock shall be
provided to prevent the circuit breaker
from being racked in or out of the service
position when the breaker is closed.

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220V to 24 V
converter for
Protection Device
Spring Charging
Handle
Plug Connector
for Aux
Contacts(Fixed &
Moveable)
Protection relay
with Lock out
release
Mechanical On
Off Button
CB Position
Indicator
CB Isolation
locking & Tagging
Spring Charge
Position Indication
CB Rack In & Out
Handle
CB Name Plate
Ratting
CB Open/Close
Indication
Air Circuit Breaker

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Molded Case Circuit Breaker:
 Molded case circuit breakers (MCCBs) can withstand amperage levels of up
to 2,500 amperes.
 It’s also used for overload and fault protection, though normally for more
energy-intensive systems.
 The adjustability of MCCBs make them particularly useful in main electric
feeders as more circuits may eventually be added to the system and thus, will
possibly require a change in the overall trip settings.
 Motor protection is also a common application for MCCBs.

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• Definition:- Relay is a device which detects an abnormal fault
condition by constantly measuring the electrical quantities which are
different under normal and faulty conditions.
Battery
Circuit
Breaker
C.T. Relay
Coil
Trip Coil
Relay operating
circuit
Tripping circuit
Sensing circuit
Relay

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Protection Relays
Numerical Relays
Feeder Protection
Transformer
Protection
Voltage
Management
Motor Protection
Electromechanical
Relays
CB Fuse failure
indication relay
CB contact
multiplier
Relay Classification

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Current Transformers
Current Transformers are used as measuring and protecting equipment, that
step down the high current to low measurable current.
Wound Type Ring Type Window/Bar
Type
Core Balance Current Transformer is a ring type current transformer, in which
three core cable or three single core cables of three phase system passes. This
transformer is normally used for earth fault protection for low and medium
voltage system.

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SWITCHES
The switches shall be TP/TPN heavy duty, air break mechanism operated by a
suitable external handle with position indicator.
FUSES
 The fuses shall be of HRC link type. Visual indication shall be provided to
indicate fuse failure.
 The motor fuse rating and characteristics shall be suitably chosen so that they
do not operate during the starting period of the motor.

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Detail Load upon Individual Unit 6.6 KV Switchgear
UAT-A
1 WORKING INCOMER OF 6.6KV UNIT SECTION 1A
2 STAND 3BY INCOMER (TIE TO ST-A)
3 BUSBAR PT
4 VENTILATION TRANSFORMER
5 U-1 LV TRANSFORMER 1A
6 U-1 ESP TRANSFORMER 1A
7 IDCT TRANSFORMER 1A
8 ID FAN 1A
9 PA FAN 1A
10 CW PUMP 1A
11 CONDENSATE PUMP 1A
12 FD FAN 1A
13 UAT-1A SPARE-1
14 TDBFBP 1A
15 MILL 1A
16 MILL 1B
17 MILL 1 C
18 Bucket Wheel Stacker 1 And Reclaimer 1A
UAT-B
1 WORKING INCOMER OF 6.6KV USECTION 1B
2 STAND 1BY INCOMER (TIE TO ST-B)
3 BUSBAR PT
4 U-1 LV TRANSFORMER 1B
5 U-1 ESP TRANSFORMER 1B
6 IDCT TRANSFORMER 1B
7 ID FAN 1B
8 PA FAN 1B
9 CW PUMP 1B
10 CONDENSATE PUMP 1B
11 FD FAN 1B
12 6.6 kV Intake Pump House 1A
13 LIGHTING TRANSFORMER
14 TDBFBP 1B
15 MILL 1 D
16 MILL 1E
17 MILL 1F
18 UAT-1B SPARE-2

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SNO. Description Rating
415 V UNIT Aux.Section in MPB(LOC: 6.3 M TG building)
PCC#A (2500KVA dry type transformer 6.6 KV/0.433 KV)
1 Emergency MCC power#A
2 Sealing air Fan#A 185 Kw
3 Vacuum pump#A 110 Kw
4 UPS #1 power supply 240 KVA
5 Condensate water Transportation pump#A 90 KW
6 BA slurry pump#A 110 Kw
7 Turbine MCC#A 255KW
8 Boiler MCC#A 329KW
9 Chemical MCC#A 52Kw
10 Boiler Motor Drive valve power supply panel 70Kw
11 In-line pump#A 75 Kw
12 Power for lighting & maintenance of switch cabinet#A 20 Kw
13 Switch cabinet Power#A 10Kw

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