In furnace we have real and reactive power, and the furnace resistance and reactance can all exhibit sudden and significant variations with time.The EAF may be switched as much as 100 times a day.The vacuum interrupter can easily handle this duty. A vacuum circuit breaker would be possible to design for switch and protect EAF systems for more than 250,000 operations. When interrupting the EAF load current high over-voltages are possible as a result of voltage escalations similar to switching inductive current. Thus, it is recommended that great attention be paid to adding surge protection to components in an EAF electrical circuit. Harmonic filter banks designed for transient, dynamic, and steady state duties, RC surge networks as well as metal oxide varistor-lightning arresters can be employed. The vacuum interrupter has great flexibility in being able to withstand high frequency TRVs. It is important, however, that any surges on the feeder and/or line side of the vacuum circuit breaker be limited by surge arrester.
