A

Industrial Visit Report

In

“400 KV Substation, Khedamara”

Submitted In partial fulfillment of requirement for the award of degree

Of

Bachelor of Engineering

In

“Electrical & Electronics Engineering”

To

Chhattisgarh Swami Vivekanand Technical University, Bhilai

In Session: 2009- 2010

Submitted by:

BOYS

B.E., 7th /4th

Department of Electrical & Electronics Engineering

Chhatrapati Shivaji Institute of Technology

[ISO 9001:2000 Certified & NBA Accredited]

Balod Road, Durg. C.G. Pin: 491001

ACKNOWLWDGEMENT

We are thankful to the organization “KHEDAMARA-400KV

SUBSTATION” to permit us for our industrial visit there. We

are also thankful to the EEE department of our college to avail

us the application for visit. We would like to thank our guide

(Mr. Sudhanshu Tripathi) who guided us during visit. Last but

not the least we thank our college for providing us the

opportunity.

CONTENTS1. About Khedamara Substation2. Machine installed at the substation

a. CVT (Capacitor Voltage Transformer) b. LA (Lightening Arresters) c. WT (Wave Trap) d. CB (Circuit Breaker) e. Isolator f. CT (Current Transformer) g. PT (Potential Transformer) h. PT (Power Transformer) i. Reactor j. Earthing k. Feeder

3. One & Half Arrangement

Khedamara, 400KV Substation

An electrical substation is a subsidiary station of an electricity generation, transmission and distribution system where voltage is transformed from high to low or the reverse using transformers.

CSEB was formed in December 2000 to manage the power sector in the newly formed state of Chhattisgarh. The board is an integrated entity for transmission, distribution and generation of power.

Transmission operations in the state are divided into two circles - Bhilai and Bilaspur. The only 400 kV Substation of CSEB in Bhilai is situated at Khedamara, Jamul Bhilai.

Machine installed at Substation

CVT (capacitor voltage transformer)

It is a transformer used for the measurement, protection and communication purposes. The transmission line is used for the power transmission as well as for communication

between the substations. It acts as a filter which blocks the frequencies above 240 kHz. The transformer maintains the line voltage across the transmission line.

LA (Lightening Arrester)

A lightning arrester is a device used on electrical power systems to protect the insulation on the system from the damaging effect of lightning .

The typical lightning arrester also known as surge arrester has a high voltage terminal and a ground terminal.

When a lightning surge or switching surge travels down the power system to the arrester, the current from the surge is diverted around the protected insulation in most cases to earth.

They are metallic lightning rods extending to the ground from a point above the highest part of the tower, the conductor has a pointed edge on one side and the other side is connected to a long thick copper strip which runs down the building. The lower end of the strip is properly earthed. When lightning strikes it hits the rod and current flows down through the copper strip.

These rods form a low-resistance path for the lightning discharge. The resistance of lightning arrester should be less than unity.

WT (Wave Trap)

This is relevant in Power Line Carrier Communication (PLCC) systems for communication among various substations without dependence on the telecom company network. The signals are primarily teleprotection signals and in addition, voice and data communication signals. Line trap also is known as Wave trap.

Trapping the high frequency communication signals sent on the line from the remote substation and diverting them to the telecom/teleprotection panel in the substation control room (through coupling capacitor and LMU).

This is relevant in Power Line Carrier Communication (PLCC) systems for communication among various substations without dependence on the telecom company network. The signals are primarily teleprotection signals and in addition, voice and data communication signals.

The Line trap offers high impedance to the high frequency communication signals thus obstructs the flow of these signals in to the substation bus bars. If there were not to be there, then signal loss is more and communication will be ineffective/probably impossible.

CB (Circuit Breaker)

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. A circuit breaker can be reset (either manually or automatically) to resume normal operation

In Khedamara air blast circuit breaker , oil circuit breaker are used The circuit breaker must detect a fault condition; in low-voltage circuit breakers this is

usually done within the breaker enclosure. Circuit breakers for large currents or high voltages are usually arranged with pilot devices to sense a fault current and to operate the trip opening mechanism

Once a fault is detected, contacts within the circuit breaker must open to interrupt the circuit; some mechanically-stored energy (using something such as springs or compressed air) contained within the breaker is used to separate the contacts, although some of the energy required may be obtained from the fault current itself.

Isolator

A disconnector or isolator switch is used to make sure that an electrical circuit can be completely de-energized for service or maintenance.

High-voltage isolation switches are used in electrical substations to allow isolation of apparatus such as circuit breakers and transformers, and transmission lines, for maintenance.

The major difference between an isolator and a circuit breaker is that an isolator is an off-load device intended to be opened only after current has been interrupted by some other control device. Safety regulations of the utility prevents any attempt to open the disconnector while it supplies a circuit

The isolation switch is not intended for normal control of the circuit and is only used for isolation.

CT (Current Transformer)

A current transformer (CT) is used for measurement of electric currents. Current transformers, together with voltage transformers (VT) (potential transformers (PT)), are 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 monitored circuit. Current transformers are commonly used in metering and protective relays.

PT (Potential Transformer)

Potential transformers are instrument transformers. They have a large number of secondary turns and a fewer number of primary turns. They are used to in Potential transformers are instrument transformers.

They are used to increase the range of voltmeters in electrical substations creating the range of voltmeters in electrical substations.

Potential Transformer is designed for monitoring single-phase and three-phase power line voltages in power metering application.

POWER TRANSFORMER

Single phase auto transformers are used at Khedamara, It is of 105 MVA rating (total of 3 units producing 315 MVA). the transformers used here are having three windings and a neutral- First the primary winding-Second secondary winding-Third is tertiary winding. The primary winding of 400kv is supply to it.The secondary winding of 220kv is for supply to load.The tertiary winding of 33kv is used for the station requirements.

REACTOR

There is one reactor in Khedamara. Their function is to :-

a) Reduce the Harmonics from supply.b) To limit the receiving end voltage and maintain a constant supply.

EARTHING

The whole base of the substation has electric grid laid in the ground for earthing purposes.

Also trench earthing is provided at the substation.

FEEDER

Khedamara has 8 nos. of 440 v feeders and 6 nos. of 220 v feeders.

One & Half arrangement

In Khedamara the two bus lines of 400 KV &220 KV. These two are connected with each other via a circuit breaker at both end of which CT

(current Transformer) is connected. Thus when fault occurs in any of the lines the circuit breaker trips and that section is

protected. This arrangement is known as 1& half circuit breaker arrangement.

CONCLUSION

The visit to Khedamara substation has been useful. We enjoyed the visit and we found out many things new while our visit and the work done there. In the end we learned about the Ideal and practical variation in working of the equipments. This visit was great-full for our knowledge.