Md. Merajul IslamID:5551310212nd batch, 5th

semesterDept. of EEE

Presented ToFarha Nazrun

Course teacherPower System-I

Arc phenomena

Resulting a current through normally nonconductive media such as air.

Temperature ionize the medium contacts(Air or oil)

Factors responsible for maintaining Arc…

1. P.D. between the contacts2.  Ionized particles between contacts

Arc resistance depends on the following factor…..

1. Degree of ionization 2. Length of arc

There are two method to extinction of arc…

1. High Resistance method.2.  Low resistance method or zero current method.

Methods of increasing arc resistance……..

1. Lengthening of arc.2. Cooling of arc.3. Reducing cross section area of arc.4. Splitting the arc.

Low Resistance or Current Zero Method...

High power a.c. circuit breakers employ this method for arc extinction.

There are some circuit breaker use different arc extinction system…

Ari-blast circuit breaker

Oil circuit breaker

SF6 circuit breaker

Vacuum circuit breaker

Disadvantages……

arc flashes produce concentrated radiant energy that can cause severe burns to

unprotected workers Numerous physical

hazards Dangerous and costly

industrial accident.

Conclusion……Arc flash accidents are very dangerous. These energy levels can produce severe burns leading to death for those within close to the arc flash.

Thanks