when the power is to be supplied

when the line is to be tested

when the switch is to be put on

whenever fault occurs in the line

high dielectric strength and thermal stability

non inflammable

arc extinguishing ability

all of the above

restriking

breaking

arc

recovery

good cooling properties and absorption of arc energy

high dielectric strength

acting as an Insulator

all of the above

Air blast circuit breaker

Minimum oil circuit breaker

Bulk oil circuit breaker

Sulphur hexafluoride circuit breaker