| 摘要 |
A method and an apparatus for extracting an active leakage current are provided to extract the active leakage current without stopping an electric device, only by pure resistor components except for reactive current generated due to earth capacitance. A method for extracting an active leakage current is composed of steps of: measuring the leakage current flowing in load impedance of an object; making first bias current having a phase corresponding to the phase of power voltage, flow in the load impedance; measuring a first compound current generated by the sum of the leakage current and a first bias current; making a second bias current having the same size of the first bias current and phase difference of 180°, flow in the load impedance; measuring a second compound current generated by the sum of the leakage current and a second bias current; and calculating a value of the active leakage current by dividing a value outputted by subtracting a square of a virtual value of the second compound current from a square of a virtual value of the first compound current, by a value outputted by multiplying the virtual value of the first bias current by 4. A zero-phase current transformer(10) measures the leakage current flowing in the load impedance of an object. |
