This is a group effort to express our experience ,we gethered in our Industrial Training.

1. A GOVERNMENT OF WEST BENGAL ENTERPRISE
A PROJECT ON
HOWRAH 220 KV SUBSTATION
PRESENTED BY:- AVIRUP GHOSH (EE/4TH YEAR/ROLL NO 24)
SUBHASHIS GHOSH(EE/4TH YEAR/ROLL NO 27)
SUMAN KUMAR GHOSH(EE/4TH YEAR/ROLL NO 28)
ARIJIT MUKHERJEE(EE/4TH YEAR/ROLL NO 49))

2. Training Duration
• We have completed our vocational
training at Howrah 220 kV Sub-station ,
Danesh Seikh Lane,Howrah from
28.12.2015 to 11.01.2016.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.

3. 3
INTRODUCTION.
220KV SUB-STATION.
ABOUT WBSETCL.
SUBSTATION.
IMPORTANT TERMS.
OVERVIEW OF HOWRAH 220/132/33 kV SUBSTATION.
MAIN ELEMENTS OF HOWRAH SUB-STATION.
PANEL SECTION.
GROUNDING.
SINGLE LINE DIAGRAM.
MAINTENANCE OF SUB-STATION.
EXPERIENCE OF CORPORAL CULTURE.
CONCLUSION.
SOURCES.

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. Type Public Sector Undertaking
Industry transmission
Founded April 1, 2007
Headquarters Kolkata, West Bengal, India
Area served West Bengal, India
Key people Sri Gopal Krishna (Power Secretary)
Products Electricity
Parent WBSEB
Website www.wbsetcl.in

8. 2008-09 2009-10 Growth (%)
Line length (ckt. km) 11,089.50 11,456.90 3.31
Substations (no.) 93 102 9.68
Transformation capacity
(MVA)
13,951.20 16,347.70 17.18
Transmission Losses (%) 3.90 2.74 -
GROWTH STATISTICS

9. TECHNICAL INFORMATION
TOTAL NO. OF EHV SUB-STATION 103
400 kV SUB-STATION 03
220 kV SUB-STATION 19
132 kV SUB-STATION 70
66 kV SUB-STATION 08
SWITCHING 03

10. DIST. NO. OF SUB-STATIONS
BANKURA 05
BIRBHUM 03
BURDWAN 10
COOCH BEHAR 01
DAKSHIN DINAJPUR 02
DARJEELING 03
HOOGHLY 11
HOWRAH 04
JALPAIGURI 12
MALDA 03
MURSHIDABAD 07
NAIDA 06
PASCHIM MIDNAPUR 07
PURBA MIDNAPUR 07
PURULIA 03
UTTAR DINAJPUR 02
24 PARGANAS(NORTH) 10
24 PARGANAS(SOUTH) 07
TOTAL 103

11. 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.

12. TYPES OF SUBSTATION
• TYPE ACCORDING TO VOLTAGE CLASS.
TRANSMISSION SUB-STATION
DISTRIBUTION SUBSTATION
COLLECTOR SUB-STATION
SWITCHING SUB-STATION
• TYPE ACCORDING TO PURPOSE
STEP UP SUBSTATION
PRIMARY GRID SUB-STATION
SECONDARY GRID SUB-STATION
DISTRIBUTION SUBSTATION
MINING SUBSTATION
MOBILE SUB-STATION

13. • TYPE ACCORDING TO CONSTRUCTIONAL FEATUREES
OUTDOOR TYPE
INDOOR TYPE
UNDERGROUND TYPE
POLE MOUNTING OPEN TYPE

14. 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

15. 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

16. 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

17. 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.

18. 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 downextra 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

19. OTHER ELEMENTS:
E.H.V. TRANSMISSION LINE
CONDUCTORS AND CABLES
BUS BARS
POWER FACTOR IMPROVEMENT EQUIPMENT
BATTERY AND BATTERY CHARGERS
SAFETY INSTRUMENTS.

20. 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

21. CONDUCTOR USED IN E.H.V.TRANSMISSION LINE
• Generally in E.H.V. transmission line MOOSE and PANTHER
conductors are used.
• Normally MOOSE are used for 220 kv & above.
• PANTHER are used for 132 kv.
Fig: Panther Conductor Fig: Moose Conductor

22. 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

23. 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.

24. 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

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

26. 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.

27. 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.

28. 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.

29. 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

30. INSTRUMENT TRANSFORMER
Fig: Current Transformer

31. 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

32. INSTRUMENT TRANSFORMER
Fig: Voltage Transformer

33. 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.

34. 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.

36. POWER TRANSFORMER
SPECIFICATIONS OF 150 MVA TRAFO-III INSTALLED AT HOWRAH 220 KV SUBSTATION:
TRANSFORMERS PARTICULARS IMPEDENCE VOLTS AND BIL(KV)
Make: CGL Impedance volts(HV-IV):11.46% at N tap
Serial no.: 24822 Impedance volts(HV-LV):45.92% at N tap
Manufacturing year: 1988 Impedance volts(IV-LV):29.81% at N tap
Commissioning date:03-Dec-90 BIL(kV)-HV:900(peak)/395(r.m.s.)
Phase: 3 BIL(kV)-IV:550(peak)/230(r.m.s.)
Frequency: 50Hz BIL(kV)-LV:170(peak)/70(r.m.s.)
Vector Group: Yna0d11 BIL(kV)-Neutral:38(r.m.s.)
Voltage ratio(kV): 220/132/33
Rated capacity(kVA): 150000

37. 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

38. BUS BAR

39. 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.

40. 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.

41. Fixed
contact
Moving
contact
ARC
Fixed
contact
Moving
contact
ARCARC IS
QUENCHED BY
MEDIUM
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.
Operating Principle

42. The Electric Arc
During the separation of contacts, due to large fault
current and high current density at the contact
region the surrounding medium ionizes and thus a
conducting medium is formed. This is called the
ARC.
Factors responsible for arc:-
Potential difference between the contacts.
Ionized particles between the contacts.

43. Arc quenching is achieved by:
Greater dielectric strength than restriking voltage.
Faster rate of heat removal than rate of heat
generation.
Arc extinction methods are:
By lengthening the gap.
Cooling the arc.
Inserting medium of high dielectric strength.
PRINCIPLES OF ARC
EXTINCTION

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

45. 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.

46. Advantages of oil:
Oil has good dielectric strength.
 Low cost.
Oil is easily available.
It has wide range of breaking capability.
Disadvantages of oil:
Slower operation , takes about 20 cycles for
arc quenching.
It is highly inflammable , so high risk of fire.
High maintenance cost.

47. 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.

49. Advantages:
High speed operation as compared to OCB.
Ability to withstand frequent switching.
Facility for high speed reclosure.
Less maintenance as compared to OCB.
Disadvantages:
Little moisture content prolongs arcing time.
Pressure should be checked frequently for
frequent operation.
Risk of fire hazards due to over voltages.
It can’t be used for high voltage operation due to
prolonged arc quenching.

50. 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.

52. Advantages:
 Very short arcing period due to superior arc quenching property of SF6 .
 Can interrupt much larger currents as compared to other breakers.
 No risk of fire.
 Low maintenance, light foundation.
 No over voltage problem.
 There are no carbon deposits.
 SF6 breakers are costly due to high cost of SF6.
 SF6 gas has to be reconditioned after every operation of the breaker,
additional equipment is required for this purpose.
Disadvantages:

53. 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.

54. Advantages:
Free from arc and fire hazards.
Low cost for maintenance & simpler mechanism.
Low arcing time & high contact life.
Silent and less vibrational operation.
Due to vacuum contacts remain free from corrosion.
No byproducts formed.
Disadvantages:
High initial cost due to creation of vacuum.
Surface of contacts are depleted due to metal vapors.

55. Circuit Breaker Comparison
SF6 CIRCUIT BREAKER
• Gas is used as an arc
quenching medium.
• It is an electronegative gas.
• It has a tendency to absorb
free electrons.
VACUUM CIRCUIT BREAKER
• Vacuum is used as an arc
quenching medium.
• It has very fast rate of recovery
of dielectric strength.
• The arc is extinguished quickly.

56. SPECIFICATION OF 220 KV CIRCUIT BREAKER INSTALLED AT HOWRAH 220 KV SUB-STATION
SL.NO. SPECIFICATION VALUES
1 FEEDER NAME 220 KV BUS COUPLER
2 RATED VOLTAGE(KV) 245
3 RATED CURRENT(AMPS) 2000
4 MAKE TELK
5 SF6/MOCB SF6
6 TYPE OFPI-200
7 SERIAL NO 860037-3
8 OPERATING AIR PRESSURE 16KG/CM^2
9 OPERATING GAS PRESSURE 6KG/CM^2
10 MFG YEAR 1994
11 COMMISSIONING DATE 30.06.1998

57. 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)

59. 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

61. Methods of Reactive Power
Compensation
• Shunt compensation
• Series compensation
• Synchronous condensers
• Static VAR compensators
• Static compensators

63. Series compensation
• When a device is connected in series with the transmission line it
is called a series compensator. A series compensator can be
connected anywhere in the line.
• There are two modes of operation – capacitive mode of operation
and inductive mode of operation.
• A simplified model of a transmission system with series
compensation is shown in Figure .The voltage magnitudes of the
two buses are assumed equal as V, and the phase angle between
them is δ.

64. Shunt compensation
• The device that is connected in parallel with the
transmission line is called the shunt
compensator. A shunt compensator is always
connected in the middle of the transmission line.
It can be provided by either a current source,
voltage source or a capacitor.
• An ideal shunt compensator provides the
reactive power to the system.
• Shunt-connected reactors are used to reduce the
line over-voltages by consuming the reactive
power, while shunt-connected capacitors are
used to maintain the voltage levels by
compensating the reactive power to
transmission line.

67. Synchronous Condensor
• A device whose main function is the
improvement of power factor of the electrical
system is known as the synchronous condensor.
It is installed at the receiving end of the line .
• When a synchronous condensor is introduced it
supplies the kVAR to the system , and hence the
current is reduced .
• Therefore the losses are reduced and provides a
better efficiency . Hence more power can be
delivered to the load and improves the power
factor of the system.

68. 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

74. 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.

75. 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.

76.  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?

77. 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

78. Functional Characteristics of a protective relay
1.Reliability
2.Selectivity
3.Speed
4.Sensitivity

79. 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.

81. TYPES OF RELAY
Types of protection relays are mainly based on their
characteristics ,logic, on actuating parameter & operation
mechanism.
 Based on operation of mechanism
1. Electromagnetic relay
2. Static relay
3. Mechanical relay
 Based on actuating parameter
1. Current relay
2. voltage relay
3. Frequency relay
4. Power relay

82.  Based on characteristics
1. Inverse time relay with definite minimum
2. Instantaneous relays
3. IDMT with Instrument
4. Stepped characteristics
5. Programmed switches
6. Voltage restraint over electric current relay
7. Definite time relay.
 Based on application
1. Primary relay
2. Back up relay

83.  Based on logic
1.Differential
2. Unbalance
3. Neutral displacement
4. Direction
5. Restricted earth fault
6. Over fluxing
7. Distance scheme
8. Bus bar protection
9. Reverse power relay
10. Loss of excitation
11. Negative phase sequence relay

84. 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.

85. 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.

86. MORE ABOUT GROUNDING
TERMS NEED TO KNOW---
EARTH RESISTENCE.
STEP POTENTIAL AND TOUCH POTENTIAL.
TYPES OF GROUNDING—
UN EARTHED SYSTEM.
SOLID GROUNDING.
RESISTENCE GROUNDING.
REACTANCE GROUNDING.
RESONANT GROUNDING.
DIFFERENT GROUNDING EQUIPMENTS---
Earthing Electrodes
Earthing Mat
Risers
Overhead shielding wire (Earthed)

87. 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.

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

89. 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.

90. 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.

92. 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.

93. 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.

94. BIBLIOGRAPHY
GUPTA,J.B.,A COURSE IN POWER SYSTEM.
KOTHARI,D.P.AND NAGRATH,I.J. POWER SYSTEM ENGINEERING.
ROY,SANJIB.DIVISIONAL ENGINEER.
MUKHERJEE,SOURAV.ASSISTANT ENGINEER.
www.wbsetcl.com
www.wikipedia.com