The document provides an overview of a training experience at the 220kV Howrah substation in West Bengal, India. It discusses the layout and purpose of the substation, including its panel, control room, and switchyard sections. It also summarizes the key equipment used at the substation, such as transformers, circuit breakers, insulators, lightning arrestors, and instrument transformers. The substation receives power from various 220kV, 132kV and 33kV transmission lines and transforms voltages for distribution.

2. A GOVERNMENT OF WEST BENGAL ENTERPRISE
A PROJECT ON
HOWRAH 220 KV SUBSTATION
PRESENTED BY:-

3. Training Duration
• We have completed our vocational
training at Howrah 220 kV Sub-station ,
Danesh Seikh Lane, Howrah on
September 26th, 2022.The objective of
this presentation is to express our
experience in a sub-station where we got
the practical outline of a system, achieved
the overview regarding the practical
usage of the power system equipment.

4. 220kV Substation
• It is divided into Three(3) parts:-
A. Panel Section
A. Control Panel Section
B. Relay and Protection Panel Section
B. Switch Yard
A. 220kV Section
B. 132kV section
C. 33kV section
C. Battery Room (Extra)

5. INTRODUCTION
• Now days the electrical power demand is increasing very rapidly. For fulfilling
these huge power demands the modern time requires creation of bigger and
bigger power generating stations. These power generating stations< may be
hydro – electric, thermal or atomic. Depending upon the availability of
resources these stations are constructed different places. These places may
not be nearer to load centres where the actual consumption of power takes
place. So it is necessary to transmit these huge power blocks from generating
station to their load centres. Long and high voltage transmission networks are
needed for this purpose. Power is generated comparatively in low voltage
level. It is economical to transmit power at high voltage level. Distribution of
electrical power is done at lower voltage levels as specified by consumers. For
maintaining these voltage levels and for providing greater stability a number
of transformation and switching stations have to be created in between
generating station and consumer ends. These transformation and switching
stations are generally known as electrical substations.

6. ABOUT W.B.S.E.T.C.L.
• West Bengal State Electricity Transmission Company Limited
(WBSETCL) was set up in 2007 following the unbundling of the state
electricity board of West Bengal. With a share of 4 percent each in the
total intrastate transformer capacity, WBSETCL is the eleventh largest
of the 23 state transmission utilities in the country. It is responsible
for power transmission across the state at the 400 kV, 220 kV, 132 kV
and 66 kV Voltage levels. The company also manages the state load
dispatch centre, which monitors and controls the grid operations.

7. SUB-STATION
A substation 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. Between the generating station and consumer, electric
power may flow through several substations at different voltage
levels. A substation may include transformers to change voltage
levels between high transmission voltages and lower distribution
voltages, or at the interconnection of two different transmission
voltages.
Substations may be owned and operated by an electrical utility, or
may be owned by a large industrial or commercial customer.
Generally substations are unattended, relying on SCADA for remote
supervision and control.
The word substation comes from the days before the distribution
system became a grid. As central generation stations became larger,
smaller generating plants were converted to distribution stations,
receiving their energy supply from a larger plant instead of using
their own generators. The first substations were connected to only
one power station, where the generators were housed, and were
subsidiaries of that power station.

8. OVERVIEW OF 220/132/25 kV HOWRAH SUBSTATION
Connected Transmission line Line Length(Km)
220 kV Howrah-KTPP double ckt 70
220 kV Howrah-Domjur double ckt via Foundary Park. 48
132 kV Howrah-Liluah 1 & 2 double ckt 12
132 kV Howrah-Liluah 3 & 4 double ckt 15(#3)/24(#4)
132 kV CESC feeder (3 circuits) 24

9. POWER TRANSFORMERS PRESENTLY IN SERVICE
3*160+1*150 MVA ,220/132/33 KV AUTO TRANSFORMER
• #1
2*20 MVA,132/25 KV TRACTION TRANSFORMER
• #2

10. BAYS WITH EQUIPMENTS PRESENTLY IN SERVICE
BUS SYSTEM BAYS WITH EQUIPMENTS PRESENTLY IN SERVICE
220 KV SYSTEM 1.Howrah-KTPP circuit1
2.Howrah-KTPP circuit 2
3.Howrah-Domjur circuit 1 via Foundary Park
4.Howrah-Domjur circuit 2 via Foundary park
5. Bus coupler Bay
6.220 kV side of 160 MVA Transformer 1
7.220 kV side of 160 MVA Transformer 2
8.220 kV side of 150 MVA Transformer 3
9. 220 kV side of 160 MVA Transformer 4
132 KV SYSTEM 1. Howrah-Liluah circuit 1
2. Howrah-Liluah circuit 2
3. Howrah-Liluah circuit 3
4. Howrah-Liluah circuit 4
5. Howrah-CESC circuit 1
6. Howrah-CESC circuit 2
7. Howrah-CESC circuit 3
8. Bus Coupler Bay
9. 132 kV side of 160 MVA Transformer 1
10. 132 kV side of 160 MVA Transformer 2
11. 132 kV side of 150 MVA Transformer 3
12. 132 kV side of 160 MVA Transformer 4
13. 132 KV side of 20 MVA 132/25 KV Traction Tr.1
14. 132 KV side of 20 MVA 132/25 KV Traction Tr.2
33 KV SYSTEM 315 MVA,33/0.4 KV Auxiliary Transformer connected at tertiary of 160 MVA Transformer 2

11. Important Terms
• Tripping – Power goes due to over load . It is for the protection of
components.
• Shut down – Power is cut due to maintenance in progress. It is done
manually.
• Break down – Power goes due to any fault in the line. When fault is
removed , power is back.
• Rosting – Power is cut deliberately on order of higher authority due
to shortage of power.

12. POWER TRANSFORMERS
Also known as the heart of
substations. These are
used to reduce the
voltages at appropriate
levels
INSTRUMENT TRANS
FORMAR
It is a used in power systems to
step down extra high
voltage signals and provide a low
voltage signal, for measurement or
to operate a protective relay
WAVETRAP AND CVT(PLCC
SYSTEM)
Traps the high frequency signals
ISOLATORS
Used for maintenance of the
circuit in no load condition
CIRCUIT BREAKER
used to protect the
eqiupment by opening the
circuit for over current and
over voltages
LIGHTINING ARRESTER
Used for protecting the
equipment from surge
voltages
MAIN EQUIPMENTS AT HOWRAH SUBSTATION
220KV

13. OTHER ELEMENTS:
E.H.V. TRANSMISSION LINE
CONDUCTORS AND CABLES
BUS BARS
BATTERY AND BATTERY CHARGERS
SAFETY INSTRUMENTS.

14. E.H.V. TRANSMISSION LINE TOWERS
• A transmission tower is a tall structure, usually a steel lattice tower, used
to support an overhead power line.
• There are four major categories of transmission towers:
SUSPENSION,TERMINAL,TENSION and TRANSPORTATION.
• Each tower shall be earthed properly. Earth strips shall be fixed to the
tower stubs during concreting of chimney.
Fig-B: Tubular Steel H-Frame Tower Fig-c: Lattice Tower With Double Circuit Fig-A: Lattice Tower With Single
Circuit

15. WIRES AND UNDERGROUND CABLES
• WIRES: Aluminum-conductor steel-reinforced(ACSR) cables are primarily used for
medium and high voltage lines and may also be used for overhead services.
Fig: Zebra Conductor Fig: Dog Conductor

16. WIRES AND UNDERGROUND CABLES
• UNDERGROUND CABLES: The design and construction of underground transmission
lines differ from overhead lines because of two significant technical challenges that
need to be overcome. These are:
1. Providing sufficient insulation so that cables can be within inches of grounded
material.
2. Dissipating the heat produced during the operation of the electrical cables.

17. INSULATORS
• An electrical insulator is a material whose internal electric charges do not flow freely and therefore
make it very hard to conduct an electric current under the influence of an electric field.
• PROPERTIES:
1. High mechanical strength in order to withstand conductor load, wind load etc.
2. High electrical resistance of insulator material in order to avoid leakage current to earth.
• TYPES:
1. PIN Type 2.SUSPENSION Type

18. INSULATORS
• TYPES:
3. STRAIN Type 4.SHACKLE Insulator
5. POST Insulator 6.GUY Insulator

19. LIGHTNING ARRESTER
• A lightning arrester is a device used on electrical power systems and
telecommunications systems to protect the insulation and conductors of the
system from the damaging effects of lightning.
• The typical lightning arrester has a high voltage terminal and a ground terminal.

20. WAVE TRAP & CVT
• WAVE TRAP: Power-line communication(PLC) carries data on a conductor that is also used
simultaneously for AC electric power transmission or electric power distribution to
consumers. Wave trap communicates between two sub-station by power lines.

21. WAVE TRAP & CVT
• CVT: The Ferro resonant transformer, Ferro resonant regulator or constant-voltage
transformer is a type of saturating transformer used as a voltage regulator.

22. INSTRUMENT TRANSFORMER
• The lines in sub-station operated at high voltage and carry current of thousands amperes. The measuring instruments and
protecting devices are designed for low voltage(110V) and current(5A).There are two types of instrument transformer-
1. CURRENT TRANSFORMER: Current transformers(CT) are a series connected type of instrument transformer. They are
designed to present negligible load to the supply being measured and have an accurate current ratio and phase relationship
to enable accurate secondary connected metering.
SPECIFICATION OF 220 KV CURRENT TRANSFORMER
Sl. No. SPECIFICATION VALUES
1 Feeder Name Domjur-II
2 Rated kV 245
3 Ph R
4 Manufacturer Alstom
5 Mfg. year 2004
6 Ratio Amps 1000-800/1-1-1-1-1
7 Connected Ratio 800
8 Burden VA 30-40-40-40-40
9 Class 05-PS-PS-PS-PS
10 Commissioning Date 03-May-07

23. INSTRUMENT TRANSFORMER
Fig: Current Transformer

24. INSTRUMENT TRANSFORMER
2.VOLTAGE TRANSFORMER: Voltage transformers(VT)(also called potential transformers(PT)) are a parallel
connected type of instrument transformer, used for metering and protection in high-voltage circuits or phasor
phase shift isolation.
SPECIFICATION OF 220 KV POTENTIAL TRANSFORMER
SL.NO. SPECIFICATION VALUES
1 Feeder Name 220 kV PT-a
2 Kv class 245
3 Phase R
4 Manufacturer Rade Koncar
5 Serial no 776089/75
6 Mfg year NA
7 Ratio 220000:110-110
8 Burden VA 300
9 Class A/B

25. INSTRUMENT TRANSFORMER
Fig: Voltage Transformer

26. POWER TRANSFORMER
• A transformer is an electrical device that transfers energy between two or more
circuits through electromagnetic induction.
ACCESSORIES OF TRANSFORMER:
CORE: The core has stepped cross-section.
WINDING: The conducting material used for the windings depends upon the
application, but in all cases the individual turns must be electrically insulated
from each other to ensure that the current travels throughout every turn.
BUSHING: Bushing is output condenser type or porcelain type depending upon
the voltage class.
OIL TANK: The tank is welded mild steel plate construction, shot blasted an inside
and outside to remove scale before painting. The tank is coated inside with two
coat of yellow oil proof enamel. On the outside it is applied with anticorrosive
primer paint and final coat of synthetic enamel to shade as per customer’s
specification.

27. POWER TRANSFORMER
PROTECTION OF TRANSFORMER: The principle relays and systems used for transformer
protection are:
Buchholz devices: Providing protection against all kinds of incipient faults.
Earth-fault relays: Providing protection against earth-faults only.
Overcurrent relays: Providing protection mainly against phase-to-phase faults and
overloading.
Differential relays: Providing protection against both earth and phase faults.

28. POWER TRANSFORMER
SPECIFICATIONS OF 150 MVA TRAFO-III INSTALLED AT HOWRAH 220 KV SUB-STATION:
RATED CURRENTS(AMPS)
ONAN ONAF OFAF
MVA AMPS MVA AMPS MVA AMPS
HV 75.00 197.00 112.50 NA 150.00 393.60
IV 75.00 328.00 112.50 NA 150.00 656.10
LV 22.50 394.00 33.75 NA 45.00 787.30
COOLING
Cooling type ONAN/ONAF/OFAF
Temp rise of oil(0c) 40
Temp rise of winding(0c) 55
Oil(main tank)(liters) 45100
Oil(OLTC tank)(liters) 510
WEIGHT
Weight(core WDG)(k.g.) 60000
Weight(accessories)(k.g.) NA
Weight(oil)(k.g.) 39460
Weight(total)(k.g.) 132800

29. BUS BAR

30. BUS BAR
• A bus bar in electrical power distribution refers to thick strips of copper or aluminum that conduct
electricity within a switchboard, distribution board, substation, or other electrical apparatus.
BUS-BAR ARRANGEMENT IN A SUB-STATION:
• Bus-bars are important components in a sub-station. There are several bus-bar arrangements that
can be used in a sub-station. They are:
i. Single bus-bar system: As the name suggests, it consists of a single bus-bar and all the incoming
and outgoing lines are connected to it.
ii. Single bus-bar system with sectionalisation: In this arrangement, the single bus-bar is divided into
sections and load is equally distributed on all the sections.
iii. Duplicate bus-bar system: This system consists of two bus-bars, a “main” bus-bar and a “spare”
bus-bar.

31. CIRCUIT BREAKER
A circuit breaker is equipment, which can
open or close a circuit under normal as well as
fault condition. These circuit breaker breaks
for a fault which can damage other instrument
in the station. It is so designed that it can be
operated manually (or by remote control)
under normal conditions and automatically
under fault condition. Whenever a fault occurs
trip coil gets energized, the moving contacts
are pulled by some mechanism & therefore the
circuit is opened or circuit breaks.

32. TYPES OF CIRCUIT BREAKERS
Oil circuit breaker
Air-blast circuit breaker
Sulphar hexafluoride circuit breaker (SF6)
Vacuum circuit breakers

33. OIL CIRCUIT BREAKER
It is designed for 11kv-765kv.
These are of two types
• BOCB (Bulk oil Circuit Breaker)
• MOCB (Minimum oil Circuit Breaker)
The contacts are immersed in oil bath.
Oil provides cooling by hydrogen
created by arc.
It acts as a good dielectric medium
and quenches the arc.

34. AIR BLAST CIRCUIT BREAKERS
This operates using high velocity blast of air which
quenches the arc.
It consists of blast valve , blast tube & contacts.
Blast valve contains air at high pressure.
Blast tube carries the air at high pressure & opens the
moving contact attached to spring.
There is no carbonization of surface as in VCB.
Air should be kept clean & dry to operate it properly.

35. SF6 CIRCUIT BREAKERS
 It contains an arc interruption chamber containing SF6 gas.
 In closed position the contacts remain surrounded by SF6 gas at a
pressure of 2.8 kg/cm2 .
 During opening high pressure SF6 gas at 14 kg/cm2 from its reservoir
flows towards the chamber by valve mechanism.
 SF6 rapidly absorbs the free electrons in the arc path to form
immobile negative ions to build up high dielectric strength.
 It also cools the arc and extinguishes it.
 After operation the valve is closed by the action of a set of springs.
 Absorbent materials are used to absorb the byproducts and moisture.

36. VACCUM CIRCUIT BREAKER
It is designed for medium voltage range (3.3-
33kv).
This consists of vacuum of pressure (1*10-6)
inside arc extinction chamber.
The arc burns in metal vapor when the
contacts are disconnected.
At high voltage , it’s rate of dielectric
strength recovery is very high.
Due to vacuum arc extinction is very fast.
The contacts loose metals gradually
due to formation of metal vapors.

37. ISOLATOR
Isolator
Used to ensure that an electrical circuit is
completely de-energised for service or
maintenance. Such switches are often
found in electrical
distribution and industrial applications,
where machinery must have its source of
driving power removed for adjustment or
repair. High-voltage isolation switches are
used in electrical substations to allow
isolation of apparatus such as circuit
breakers, transformers, and transmission
lines, for maintenance. The disconnector is
usually not intended for normal control of
the circuit, but only for safety isolation.
Disconnector can be operated either
manually or automatically (motorized
disconnector)

39. STEPS OF OPERATION OF ISOLATOR
SEQUENCE OF STEPS FOR ATTENDING
MAINTENANCE:
1. Open CB on no load or full load
2. Open the isolator on no load
3. Close the earth switch
SEQUENCE OF STEPS FOR KEPT IN SERVICE
1. Open the earth switch
2. Close the isolator
3. Close the CB

40. Battery Room &
Charger
•It is responsible of supplying all the
relay panels which are situated in
control room
•Typically room containing the battery
bank is dark in color to avoid the
evaporation of solution inside the
battery

42. Panel Section
• It is a room which contains all types of panels.
• Typically a control panel consists of
 Metering Equipments.
 Controlling Equipments.
 Protective Relaying.
• Control Cables are laid between Switchyard
equipment and these panels.

43. Importance of control panel
• Control and Relay panel is most important equipment of the substation
as it work as shield guard for all substation equipments and electrical
network. Moreover, these panels are useful to control the flow of
electricity as per the Voltage class and detect the faults in transmission
lines.

44.  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: system aging, lightning, etc.
Why A System Needs Protection?

45. PROTECTIVE RELAY
Current
Voltage
Insulation
Temperature
Pick up levels
Time
Visual indication
Warning alarm
Remove power
output
input
setting
A protection relay is a smart device that receive inputs, compares them to set
points, and provide outputs .
Inputs can be current ,voltage ,resistance or temperature.
Outputs can include visual feedback in the form of indicator lights.
A diagram is shown below.
Relay

46. OPERATING PRINCIPLE
 There are really only two fundamentally different
operating principles,
1. Electromagnetic attraction
2. Electromagnetic induction
 Electromagnetic attraction relays operate by virtue of
a plunger being drawn into a solenoid.
 Electromagnetic induction relays use the principle of
the induction motor whereby torque is developed
by induction in a rotor.

47. Importance of relay
•By adequate protection the damage can be eliminated
or minimized.
•Inadequate protection can lead to a major fault that
would have been avoided.
•If the faulty part is disconnected quickly the damage
caused by fault is minimum.
•The protective relaying helps in improving service
continuity and its importance to self evident.

48. SUB STATION GROUNDING
Sub-station grounding is needed -------
• To provide discharge path for lightning over voltages coming via rod-
gaps, surge arresters, and shielding wires etc. .
• To ensure safety of the operating staff by limiting voltage gradient at
ground level in the substation
• To provide low resistance path to the earthing switch earthed
terminals, so as to discharge the trapped charge (Due to charging
currents even the line is dead still charge remains which causes
dangerous shocks) to earth prior to maintenance and repairs.

49. MAINTENANCE OF A SUB-STATION
Maintenance is classified in two categories as follows:
• The breakdown or corrective maintenance activities are undertaken
after failure of an equipment. Such maintenance results in outage of
circuit and supply. In general, it consists of locating the trouble,
repair and re commissioning.
• The preventive maintenance is undertaken to ensure smooth and
efficient working of a system, equipment. Preventive maintenance is
undertaken as per schedule before breakdown of a system or
machine takes place.

50. ACTIVITIES RELATED TO MAINTENANCE
INSPECTION.
SERVICING.
EXAMINATION.
OVERHAUL.
REQUIRMENTS OF THE ABOVE VARY WITH
ENVIRONMENTAL ASPECTS.
OPERATING DUTY.
SWITCHING DUTY SEVERITY.

51. WHAT IS SINGLE LINE DIAGRAM?
A single line diagram is diagrammatic representation of power
system in which the components are represented by their symbols
and interconnection between them are shown by a straight
line(even though the system is three phase system).The ratings and
the impedances of the components are also marked on the single
line diagram.
So One-line diagram or a single line diagram is a diagram that uses
single lines and graphic symbols to indicate the path and
components of an electrical circuit.

52. PURPOSE AND EXAMPLE
One-line diagrams are used when information about a circuit is required but
detail of the actual wire connections and operation of the circuit are not.
The purpose of the single line diagram is to supply in concise form of the
significant information about the system.

54. OTHER ASPECTS OF INDUSTRIAL TRAINING
LET US REVISE WHAT ARE THE PURPOSES OF AN INDUSTRIAL TRAINING????
THEN WHAT MORE???
 WE OFTEN FORGET ABOUT THE SOFT SKILL IT OFFERS.
 CORPORATE COMMUNICATION.
 CORPORAL WORK ENVIRONMENT.
 CORPORATE CULTURE.
 OVERVIEW OF PROFESSIONAL RESPONSIBILITIES.
 CORPORATE MANARISM AND OTHER SOFT SKILL.

55. CONCLUSION
• An Engineer need to have not just theoretical but practical as well as
and so every student is supposed to undergo a practical training
session. where one may have impaired the knowledge about
transmission ,distribution . One must have never thought that so
many things are required for just switching on a television or a
refrigerator or say an electric trimmer. The three wing of electrical
system viz. Generation, transmission and distribution are connected
to each other and that too very perfectly. Lots of labour, capital and
infrastructure is involved in the system just to have a single
phase,220V,50Hz power supply at our houses.