High Voltage circuit breaker (including breakers rated at intermediate voltage) is used for service on circuits with voltage ratings higher than 600 volts. Standard voltage ratings for these circuit breakers are from 4,160 to 765,000 volts and three-phase interrupting ratings of 50,000 to 50,000,000 kVA.
In the early stage of electrical system , the major portion of high-voltage circuit breakers were oil circuit breakers. Later, magnetic and compressed-air type air circuit breakers have been developed and are in use today.