132KV Sub-Station RRVPNL,

• 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

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 substationTransmission substation connects two or more

transmission lines.Distribution substation transfers power from

transmission system to the distribution system of an area.

COMPONENTS USED

• ISOLATERS

• CIRCIUT BREAKERS

• INST. TRANSFORMERS

• RELAYS

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

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 busbarAuxiliary busbarOne busbar is main busbar & another is spare

or auxilary busbar.

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.

CLASSIFICATION:- oil circuit breakers Sulphur Hexa Fluoride circuit breakers Air-Blast circuit breakers vaccum circuit breakersUnder training SF6 type, vaccum ckt breaker &

Air-Blast ckt breakers were used in the GSS.

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.

MAIN PARTS OF POWER TRANSFORMERS:-a)coreb)Winding(H.V winding, L.V winding, tertiary

winding)c)Tap changerd)Tank e)Conservatorf)Aircellg)Buchholz relayh)Dehydrating breatheri)Oil temperature indicatorj)Winding temperature indicator

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.

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.TProtective 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.

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.

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.

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

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

REQUIREMENT OF DC SYSTEM

• BATTERY• HYDRO METER

QUERY