2. Electrical substation consists of a number of
incoming circuits and outgoing circuits
connected to common busbar system. Busbars
are conducting bars to which a number of
incoming or outgoing circuits are connected.
A substation receives electrical power from
generating station via incoming transmission
lines and delivers electrical power via the
outgoing transmission lines.
4. A transformer is an electrical device that transfers
electrical energy between two or more circuits through
electromagnetic induction. Commonly, transformers are
used to increase or decrease the voltages of alternating
current in electric power applications.
Transformer is a static machine, which transforms the
potential of alternating current at same frequency.
This substation has two types of transformer:-
-Two 165MVA 220/132kV transformers
- One 315MVA 400/220kV transformer
5. Cooling fans are used for forced air
cooling of the transformer
165 MVA uses six cooling fans
315 MVA uses eight cooling fans
All fans not start at the same time.
They start in pairs.
6. In electrical engineering, a current
transformer(CT) is used for measurements of
electric currents.Current transformers, together
with voltage transformers(VT)(potential
transformers(PT)), are known as instrument
When current in a circuit is too high to directly
apply measuring instruments, a current
transformer produces a reduced current
accurately proportional to the current in the
circuit,which can be conveniently connected to
the measuring and the recording element.
7. A capacitor voltage transformer (CVT) is a transformer
used in power systems to step-down extra high voltage
signals and provide low voltage signals either for
measurement or to operate a protective relay.
In its most basic form the device consists of three
parts: two capacitors across which the voltage signal is
split, an inductive element used to tune the device to
the supply frequency and a transformer used to isolate
and further step-down the voltage for the
instrumentation or protective relay.
8. A circuit is a automatically operate switch designed to protect the system during shortcircuit
or abnormal conditions.
Below shown is of SF6 circuit breaker.
9. In electrical engineering, a
disconnector, disconnect switch
or isolator switch is used to
ensure that an electrical circuit is
completely de-energized 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.
10. Surges, or transients, are brief
overvoltage spikes or disturbances on a
power waveform that can damage,
degrade, or destroy electronic
equipment within any home,
commercial building, industrial, or
The overvoltage protection is obtained
by the use of lightning/surge arresters.
Lightning Arresters or Surge Arresters
are always connected in shunt to the
equipment to be protected, they provide
a low impedance path for the surge
current to the ground.
Mostly in present days zinc oxide(Zno)
gapless arresters are in use
11. In electrical engineering, a protective relay is
a device designed to trip a circuit breaker
when a fault is detected.
The first protective relays were
electromagnetic devices, relying on coils
operating on moving parts to provide
detection of abnormal operating conditions
such as over-current, over-voltage, reverse
power flow, over- and under- frequency.
Microprocessor-based digital protection
relays now emulate the original devices, as
well as providing types of protection and
supervision impractical with
12. Wave trap are used for carrier
It traps the higher frequency
above 50 Hz.
It is the effort to utilize the
same transmission line
between to substation for the
purpose of communication
14. The control panels and relays of
the substation require DC
supply of 220V.This DC supply
is made with the help of battery
bank reserve normally kept in a
separate room called Battery
The batteries used in this
substation are Nickel-Cadmium
15. The control room has various control panels which shows the
information like incoming power, outgoing power, frequency,
time common to all substations, status of various lines
(healthy, faulted, under outage or maintenance), status of
various protective instruments like isolators, circuit breakers;
temperatures of various instruments, working tap of
The relay room is separate from the control room. All relays
used here are numerical and are either from Siemen ”OR
The protection system is so fast that it can detect a fault within
30 ms and hence the circuit breaker can be operated within as
less as 80 ms. For 400 kV side C.B.