| 摘要 |
Three-pole circuit-breakers incorporating residual current protection is provided of which not only an earth leakage detecting function but also the function of an earth leakage current test device can be made to work normally whichever phase of a 3-phase circuit fails, without its construction being made complicated. In circuit-breakers incorporating residual current protection having a zero phase current transformer 5 with the three power lines 3 of a 3-phase circuit passing through it, for detecting an earth leakage current of the 3-phase circuit, an earth leakage detecting circuit 7 for performing a level determination on a signal outputted by this zero phase current transformer 5, an electromagnetic device 8 for responding to the output of this earth leakage detecting circuit 7 by opening circuit contacts 4, and an earth leakage current test device 12, to be operated at the time of an earth leakage test, for passing a test current through the zero phase current transformer 5, the earth leakage detecting circuit 7 and the electromagnetic device 8 receive a supply of operating power from the three power lines 3 of the 3-phase circuit by way of a rectifier circuit 10 and the earth leakage current test device 12 is connected to the output terminals of the rectifier circuit 10. |
