ABSTRACT

The Project work at BHARATH HEAVY ELECTRICALS LIMITED,

RAMACHANDRAPURAM proposed to be carried out by the following members is on

“STUDY OF EHV CIRCUIT BREAKER”. This project involves understanding of

various aspects of EHV circuit breaker.

Circuit breaker is considered to be one of the most critical equipment in

modern day power system. Its importance lies not only in its fault clearing ability and

protecting high value equipment connected to that system but also in maintaining

stability of the connected healthy part of the power system.

Circuit breakers can be broadly classified based on various criteria like voltage

level, interrupting media, application, external design etc. But present day breakers

are dominated by SF6 gas breakers.SF6 gas with its superior arc quenching properties

have replaced all other interrupting media.

Circuit Breakers have to perform various switching duties varying like

switching high magnitude short circuit currents, normal load currents, low magnitude

capacitor currents, reactor current switching which pose different arduous conditions

like RRRV, Recovery voltage, travelling wave voltage surges, Electromagnetic forces

while interrupting various type of currents. Breakers are designed to overcome all

those constraints and successfully interrupt all types of circuits with in specified time.

Different types of Arc quenching techniques are applied in the breakers. There

is lot of evolution in these techniques varying from first generation compressed gas

quenching technique to present day third generation technique which utilizes the arc

energy to quench it. These changes have made it possible to use low energy operating

mechanisms like spring mechanisms which are of low cost and maintenance free,

giving customer trouble less performance.