| 摘要 |
<p>PURPOSE:To make the constitution simple and small, and to reduce the detected level of a ground current much more, by making possible the detection of an inverter input direct current and the ground fault current by a set of detectors for current including a current transformer. CONSTITUTION:A current detecting circuit 3 consists of a current transformer, and a current detector for receiving the output voltage of the Hall element 3a of the transformer to discriminate between an input direct current and a ground current and to detect the magnitude of each current. In the transformer, currents I1, I2 are allowed to flow on the same iron core having the element 3a inserted into its opening part, and the predetermined turn difference eta is provided between the first and second coils the numbers of turns of which are N1, N2 respectively. The directions of magnetic fluxes phi1, phi2 generated through both coils become opposite to each other. The ground fault current I3 flows into the ground through a virtual switch 6. By such a circuit constitution, the discrimination of currents I1 and I2 by polarity and the detection of each magnitude can be made by using a set of detected signals of the transformer, and the reduction of the detection level can be made together with the sharp detection.</p> |
