| 摘要 |
A device for detecting a fault in an AC supply comprising a detection circuit (CT1, W1a, U1) for detecting a fault in an AC supply to a load and providing a corresponding output (30). A disconnect circuit (SCR1, SCR2, K1, SW1, SW2) disconnects the load from the supply in response to an output (30) from the detection circuit. The device also includes a generator (40) of intermittent test pulses, and a test circuit (Q2, D11, R12, W2, K1, R9) coupled to the detection circuit (CT1, W1a,U1) and containing a first solid state switch (Q2). Each test pulse turns on the solid state switch (Q2) for the duration of the test pulse so that a current simulating the fault flows intermittently in the test circuit and a corresponding output (30) is provided by the detection circuit (CT1, W1a,U1). The device further comprising means to disable the disconnect circuit (SCR1, SCR2, K1, SW1, SW2) in response to each test pulse. |
