2. • GENERAL DISCUSSION ON SUB STATIONS
• LAYOUT OF 132 KV GSS
• SINGLE LINE DIAGRAM
• COMPONENTS USED
• ISOLATERS
• BUSBARS
• CIRCIUT BREAKERS AND ITS CLASSIFICATION
• POWER TRANSFORMERS AND ITS MAIN PARTS
• INSTRUMENT TRANSFORMERS
• CURRENT TRANSFORMERS
• BUCHOLZ RELAY
• EARTHING
• POWER LINE CARRIER COMMUNICATION
3. Substation:- A station is a subsidiary station of an
electricity generation, transmission, & distribution system
where voltage is transformed to high to low or the reverse
using transformers.
A substation generally have switching, protection, & control
equipment & one or more transformers.
Types:-
(a) Transmission substation
(b) Distribution substation
Transmission substation connects two or more transmission
lines.
Distribution substation transfers power from transmission
system to the distribution system of an area.
4. The present day N.P.H. GSS was formerly a thermal
power house with generation capacity of 3 kw each .
There was also a railway line for direct supply of coal to
power house. However with due course of time this
had to be abandoned because of problems like
pollution & inability to meet the power supply.
The load requirement of about 200 MW of present day
is being obtained from interconnected grid system.
There are two incoming feeders from 220kv baasni 2nd
phase, 3wire system and reduce the voltage to 33kv &
11kv GSS. One of them goes to tinwari.
7. Isolators are designed to open a ckt under n0 load. Its
main purpose is to isolate portion of ckt from the
other & is not intended to be opened while current is
flowing in the line.
There are two types of isolators:-
off load isolators
on load isolators
8. 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,
busbar 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 busbar
Auxiliary busbar
One busbar is main busbar & another is spare or auxilary
busbar.
9. A circuit breaker is a piece of equipment which can:-
break a ckt automatically under fault conditions.
make a ckt either manually or by remote control
under fault conditions.
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.
10. CLASSIFICATION:-
oil circuit breakers
Sulphur Hexa Fluoride circuit breakers
Air-Blast circuit breakers
vaccum circuit breakers
Under training SF6 type, vaccum ckt breaker & Air-Blast
ckt breakers were used in the GSS.
11.
12. 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.
13. MAIN PARTS OF POWER TRANSFORMERS:-
a) core
b) Winding(H.V winding, L.V winding, tertiary
winding)
c) Tap changer
d) Tank
e) Conservator
f) Aircell
g) Buchholz relay
h) Dehydrating breather
i) Oil temperature indicator
j) Winding temperature indicator
14.
15. 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.
16. 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. There are two classes of
C.T:
protective C.T
measuring C.T
Protective C.Ts are used for over current protection, earth
fault protection, differential protection& impedence
protection, etc.
Measuring C.Ts are used with ammeters, wattmeters, KV
meters & KWH meters for reducing line.
17.
18. Potential transformers are instrument transformers.
They have a large number of secondary turns and a
fewer number of primary turns. They are used to
increase the range of voltmeters in electrical
substations and generating stations.
These are also called as voltage transformers used for
line and circuit protections.
19.
20. Definition:- Buchholz relay is a gas actuated relay. It
can only be fitted to the transformers equipped with
conservator tanks as it is installed in b/w the
conservator tank and the main tank i.e., the pipe
connecting the two.
Principle:- Whenever a fault occurs inside the
transformers, the oil of the tank gets overheated and
gases are generated.
The heat generated by the high local current causes the
transformer oil to decompose and produce gas which
can be used to detect the faults.
21. Operation:- When a fault occurs, heat is produced due
to current leakage, some of the oil in the transformer
tank evaporates and some vapours collect in the top of
the chamber while passing to conservator tank. When
a predetermined amount of vapours accumulate in the
top of the chamber, the oil level falls, and so closes the
alarm circuit of the relay and rings the bell. Thereby
the operator knows that there is some fault occurred in
the transformer.
22.
23. Connection of an electric equipment to the earth with
the help of connecting rod or wire of negligible
resistance is known as earthing.
Methods of earthing arrangments at 132 kv GSS:
pipe earthing
plate earthing
24.
25. 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
