| 摘要 |
<p>PROBLEM TO BE SOLVED: To connect a plurality of inverters in series or in parallel to each other and detect ground leakage in the respective inverters easily. SOLUTION: Resistors R1-R4 are connected between the output terminals of inverter circuits 401 and 402 so as to form a bridge. Divided voltages of the respective middle points M1 and M2 are inputted to a differential amplifier 25. Particularly, the middle point M2 is connected also to an earth terminal E. If a ground leakage occurs, a difference between the voltages at the middle points M1 and M2 which are divided by resistors is produced and the output of the differential amplifier 25 is changed. If the change of the output is larger than a threshold, it is judged that the ground leakage exists.</p> |
