The document discusses various components used in electrical substations. It describes key equipment like transformers, circuit breakers, isolators, busbars, instrument transformers, and protection devices. It also discusses the purpose of a substation to step up or down voltages for transmission or distribution and provide protection for the transmission system. The control room is mentioned as the place from where all substation equipment is monitored and controlled.

1. Submitted To:-
Dr. Dinesh Birla
(Professor)
MR. Ashok Kumar Sharma
(Associate professor)
Submitted BY:-
Abhishek Dosaya
Roll no.- 13/003
7th sem,Btech,EE

3. Substation:- From where electricity is transmitted or
distributed.
Step up for long distance transmission
Step down for distribution purpose
A substation generally have switching, protection, & control
equipment & one or more transformers.
Purpose of substation:-
 Protection of transmission system.
 voltage control; reducing the reactive power flow by compensation of
reactive power.
 Ensuring the stability of the network.
 Determining the energy transfer through transmission line.
 Data transmission via power line carrier for the purpose of network
monitoring , control and protection.
 Fault analysis and recover

5. DEFINITION:- A bus bar is a conducting bar that
carries heavy currents to supply several electric
circuits.
When a no. of generators or feeders operating at the
same voltage level to be directly connected electrically,
Bus bar are used as the common electrical component.
Bus bars are copper rod or thin walled tubes and
operate at constant voltage.
TYPES OF BUSBARS:-
 Main Bus bar
 Auxiliary Bus bar
One Bus bar is main Bus bar & another is spare or
Auxiliary Bus bar.

6. When any apparatus become faulty which is directly
connected to main Bus bar then we use auxiliary bus bar
to keep supply continue.

7.  Lightning arrester is a
protective device which
provides protection against the
high voltage from lightning.
 A lightning arrestor has two
terminal one is the high
voltage terminal and one
terminal is ground.
 It is used only from overhead
line
 Zno type LA are mostly used.

9. Close Condition
Open Condition

10. A circuit breaker is a equipment which can:-
 break a ckt automatically under fault conditions.
 make a ckt either manually or by remote control .
PRINCIPLE:- A ckt breaker essentially consists of fixed
& moving contacts, called electrodes under normal
operating conditions, these contacts remain closed &
will not open automatically until & unless the systems
becomes faulty. When a fault occurs on any part of the
system, the trip coils of the breaker get Energised &
the moving contacts are pulled apart by some
mechanism. Thus opening the circuit.

11. It is generally used in on load condition.
CLASSIFICATION:-
 oil circuit breakers
 Sulphur Hexa Fluroide circuit breakers
 Air-Blast circuit breakers
 vaccum circuit breakers
Under training SF6 and oil circuit breaker were used
in the GSS.

13. Isolator is used When current is not
flowing into the line, because there is no
arc interrupting medium But Circuit
breaker is used on load condition
because arc interrupting medium is
available.

14.  Transformer is an electrical machine
which works on the principle of
electromagnetic induction.
 It transfers electric power from one electric
ckt to other with the help magnetic
path(flux) on constant frequency but
equal or different current voltages.
 For this purpose two sets of insulated
windings are wounded on a close
terminated steel core.
 The winding which is connected to the
supply is called primary winding & that
winding is connected to the load is called
secondary winding.

15. 1. Three limb core
2. LV winding
3. HV winding
4. LV bushings
5. HV bushings
6. Transformer oil
7. Tap changer
8. Conservator
9. Breather
10. Buchholz relay
11. Radiator

16. Instrument transformers are used for measurement
and protective applications together with equipments
such as meters & relays.
The lines in a station are operated at high voltages and
carry currents of thousands of amperes. The
measuring and protective devices are designed for low
voltage generally 100v and currents about 5A, therefore
they will not work satisfactory if mounted on the
power lines. This difficulty can be overcome by using
instrument transformers, which will step down the
voltages and currents to the convenient level for the
operation of measuring instruments & relays.

17.  C.T. is an instrument transformer used for
protection & metering of high values of currents.
C.T. is used for reducing A.C. from higher to lower
value for measurement/protection/control.
 Turns Ratio normally 1:1000
 IS= IP * NP / NS
 CT rating 100/5 and 20/1 is not same because this is
the input/output rating(not turns ratio).
 Secondary of CT is short circuited due to following
reasons:-
1. If the secondary is open circuited , no current flow
secondary side, so no counter magnetic field , flux
in the core saturates and char. Of CT changes and
damage permanently
2. No of sec. turns high , so high voltage induce which
can harm the persons working on the panel
 CT consist of single core in high voltage side
and 3 0r 4 cores in low voltage side.

19. >

20. Potential transformer (voltage
transformer) is used for protection and
measurement.Voltage transformer is
necessary for directional, voltage, distance
protection.
 A PT or sometimes called VT is a step-
down transformer having many primary
turns but few secondary turns.
 In a step-down transformer the voltage
decreases and the current increases, thus
voltage can be easily measured by using a
low-range voltmeter instrument.
Oil cooled PT
A VT is a "stepdown transformer" that steps down voltage from a very high voltage
level(200KV,...) to a lower level(110V). Since, the power(P=VI) in a
transformer(input and output) is same, the current rises to a very high level. Thus,
a very high resistance is maintained at the secondary terminal to limit the
current(which appears as open circuit)

23. A capacitor voltage
transformer (CVT or CCVT), is
a transformer used in power
systems to step down extra high
voltage signals and provide a low
voltage signal, for metering or
operating a protective relay.
Capacitor Voltage
Transformers also serve as coupling
capacitors for coupling high
frequency power line carrier signals
to the transmission line.

24. In practice, capacitor C1 is
often constructed as a stack
of smaller capacitors
connected in series. This
provides a large voltage
drop across C1 and a
relatively small voltage drop
across C2. As the majority of
the voltage drop is on C1,
this reduces the required
insulation level of the
voltage transformer. This
makes CVTs more
economical than the wound
voltage transformers under
high voltage (over 100kV)

25.  A relay is automatic device which senses an abnormal
condition of electrical circuit and closes its contacts. These
contacts in turns close and complete the circuit breaker trip
coil circuit hence make the circuit breaker tripped for
disconnecting the faulty portion of the electrical circuit from
rest of the healthy circuit.
 Based on application the protection relay can be categorized
as- Primary relay.
Backup relay.
 Primary relay or primary protection relay is the first line of
power system protection whereas backup relay is operated only
when primary relay fails to be operated during fault. Hence
backup relay is slower in action than primary relay.

26. 1.
132 KV
Transmission Line
Main Protection :
Switched distance
scheme (fed from
bus PT).
Backup Protection:
3 Nos. directional
IDMT O/L Relays
and
1 No. Directional
IDMT E/L relay.
2. 33 KV lines
Non-directional
IDMT 3 O/L and 1
E/L relays.
3. 11 KV lines
Non-directional
IDMT 2 O/L and 1
E/L relays.

27. 132/33KV,40/
50 MVA
3 nos
O/L
Relay
1 no
Directio
nal E/L
Relay
3 nos O/L Relay
1 no E/L Relay
Differential Relay
Over flux Relay
Buchholz Relay
OLTC Buchholz
Relay
PRV Relay
OT Trip Relay
WT Trip Relay

28.  For compensate the reactive power, we use capacitor
bank.
 Advantage-
 It reduces Line current of the system.
 It improves voltage level of the load.
 It improves power factor.
It is subdivided into two categories:-
1. Shunt capacitor
2. Series Capacitor

29. Inductive load increase,
Reactive power more absorb,
Q(+) increase, power factor
decrease
To deliver the required active
power, I increases so the
ampere burden increases and
more losses take place or
voltage dip(black out
situations)

30. The main reason for doing earthing in electrical
network is for the safety. When all metallic parts in
electrical equipments are grounded then if the
insulation inside the equipments fails there are no
dangerous voltages present in the equipment case.
To save human life from danger of electrical shock or
death i.e. To provide an alternative path for the fault
current to flow
To lightning overvoltage protection
Methods of earthing arrangments at 132 kv
GSS:
 pipe earthing
 plate earthing

33.  Control room is a place from where we control all the
actions on all equipment in the yard.
 The control room work on 110V Dc supply. These supply are
taken from the station transformer By convert ac to dc through the
rectifiers. In the case of failure of ac supply. DC supply voltage will
be available automatically from the lead acid battery.
 Control Panels: Control panels contain meters, control
switches and recorders. These are used to measure all
readings and to control the substation equipment, to send
power from one circuit to another or to open or shut down
circuits when needed.
 Relay Panels: In Which the different types of relays
are present for different fault protection, and
indicate that type of fault

35. The control room work on
110V Dc supply. These supply
are taken from the station
transformer By convert ac to
dc through the rectifiers. In
the case of failure of ac
supply. DC supply voltage will
be available automatically
from the lead acid battery.
In battery rooms 55 batteries
of each 2v is connected in
series to provide 110v.

36.  For exchange of dates and transfer
message between grid
substation,voice communication is
necesarry. for this purpose high
frequency carrier current is
transmitted on same transmission
line on which power is
transmitted.
 Hence such communication is
called “power line communication.
 High frequency signal is
transmitted and received Through
coupling capacitor and is trapped
by line trap unit(parallel
combination of L and C).

38. Its was great experience for me, I have more cleared my
theoretical knowledge with the practical knowledge and
learn that how do complex distribution be successful so
that we may get continuous power supply.