Current transformer

The transformer:type I (square circuit hole)capable of passing through either the cable or the purpose of monitoring. Type II(horizontal square hole)capable of passing through 1-3bus bar(s)is gnerally used for the purpose of monitoring.Type III (vertical square hole)capable of passingthrough 1-3 bus bar(s)has the same characteristics of Type I and II,and is also intended to measure theelectricenergy of powersupply system(Class 0.2).It can still be used at larger secondary impedance and act as the zero-sequence current transformer.