Components & Operations of 132 / 33 KV SUBSTATION

Chhattisgarh State Power Transmission Company Ltd.(A successor division of CSEB)KACHNA, RAIPUR.

INTRODUCTIONSubstation, Kachna is situated at 5 kms from Raipur.The main purpose of this substation is to step down

the supply voltage from 132 KV to 33 KV. The 132 kV supply is incoming from Urla 1, Urla 2 &

Mahasamund.The two transformers with rating 40 MVA & one with

63 MVA steps down the supply voltage from 132KV to 33 KV and is supplied to 9 different feeders & 4 feeders in spare for future use, however one more transformer of 200 KVA is used to convert 33kv to 0.4 kv for the internal use of the substation.

INTRODUCTIONFeeders are lines from which supply passes to

the area.The feeders feeds the supply line to the

following areas:Mandir HasaudVidhan SabhaAshoka RatnaShanker Nagar PurenaMana

Components of 132KV SubstationSingle line Connection Diagram

Transformer

Current/Potential Transformer

Circuit Breaker

PLCC

Single Line Connection Diagram

Transformer

TransformerIntroduction:

SPECIFICATION of Transformer used in 132 kv SubstationContinuous Rating MVA : 63

Phase : 3

Frequency: 50Hz

Normal voltage rating at no load :132/33 KV

SPECIFICATION of Transformer used in 132 kv SubstationConnection : star-star

Vector group: YNyno

Tapping rate: +5% to -15% in 1.25% steps of HV & LV

Current Transformer

Current Transformer A current transformer (CT) is used for measurement

of electric currents. Current transformers are also known as instrument transformers. When current in a circuit is too high to directly apply to measuring instruments, a current transformer produces a reduced current accurately proportional to the current in the circuit, which can be conveniently connected to measuring and recording instruments. A current transformer also isolates the measuring instruments from what may be very high voltage in the primary circuit. Current transformers are commonly used in metering and protective relays in the electrical power industry.

Current TransformerWORKING PRINCIPLE

The most common design of CT consists of a length of wire wrapped many times around a silicon steel ring passed over the circuit being measured. The CT's primary circuit therefore consists of a single 'turn' of conductor, with a secondary of many hundreds of turns. The primary winding may be a permanent part of the current transformer, with a heavy copper bar to carry current through the magnetic core.

Principle of CURRENT TRANSFORMER

Usage of C.T.Current transformers are used extensively for

measuring current and monitoring the operation of the power grid. Along with voltage leads, revenue-grade CTs drive the electrical utility's watt-hour meter on virtually every building with three-phase service, and every residence with greater than 200 amp service.

The CT is typically described by its current ratio from primary to secondary. Often, multiple CTs are installed as a "stack" for various uses (for example, protection devices and revenue metering may use separate CTs). Similarly potential transformers are used for measuring voltage and monitoring the operation of the power grid.

Circuit BreakerINTRODUCTION:A circuit breaker is an automatically-operated electrical

switch designed to protect an electrical circuit from damage caused by overload or short circuit. Its basic function is to detect a fault condition and, by interrupting continuity, to immediately discontinue electrical flow. Unlike a fuse, which operates once and then has to be replaced, a circuit breaker can be reset (either manually or automatically) to resume normal operation. Circuit breakers are made in varying sizes, from small devices that protect an individual household appliance up to large switchgear designed to protect high voltage circuits feeding an entire city.