Current Transformer, measured current and monitored the operation of the power grid to isolate the measuring instruments from what may be high voltage in the monitored circuit, Which is commonly used in metering and protective relays. With high accuracy and reliability, rated test voltage general up to3KV AC RMS for 1minute, encapsulated in fire-retardant plastic, operating temperature between -10℃ ~ 50℃ and relative humidity upto 80%.