| 摘要 |
A residual current switching device (14) comprises live and neutral terminals (32, 34), outgoing load terminals (36) electrically communicable with the respective live and neutral terminals (32, 34), and a switching device (22) between at least one of the live and neutral terminals (32, 34) and its respective outgoing load terminal (36). There is also a sensing element (24) for sensing a nonzero sum of currents between the said terminals, a sensing circuit (26) for receiving a sensing signal from the sensing element (24), the sensing circuit (26) controlling the switching device (22) to open based on the sensing signal from the sensing element (24), and a timer circuit (28) for automatically periodically outputting a test signal and having a user interface (29) for manually setting a specific time of day that said periodic test signal is outputted. A warning circuit 30 having a warning device (56) is also provided from which an alert signal is outputable following output of the test signal from the timer circuit (28). Preferably, the timer circuit (28) outputs the test signal to the sensing circuit (26), whereby the switching device (22) is controlled by the sensing circuit (26) to open based on the test signal. A warning signal is thus outputable by the sensing circuit (26) to the warning circuit (30) to activate the warning device (56) if the switching device (22) does not open on outputting of the test signal from the timer circuit (28). Optionally, the test signal is outputable from the timer circuit (28) to the warning circuit (30) to directly activate the warning device (22) without control of the switching device (22). |
