ZW27K-12 Outdoor AC End-user Sectionalized Vacuum Circuit Breaker.The circuit fault was reduced after trolly wire was replaced by insulate wire,
power transformer through low resistance to earth to simple the rely protection,under this condition, the substation circuit was trip when single phase current on a fixed data, power off for all the line. So this entry- house circuit
breaker will be selected.
One minute power frequency withstand voltage-dry(42kV)