The leakage current protection device, or ground fault circuit protection device, is used to detect the ground fault current produced in electrical systems, instrument, devices, equipment and power supply systems, when the ground fault current exceeds specified limit, the circuit protection device will automatically shut down the power supply and so as to protect human being and properties. In actual application, the leakage current protection device or ground fault circuit protection device may partly or wholly malfunction, and the protection device thereby may malfunction, but users do not know that, and safe risk may occur. In actual application, for the circuit protection device with both load terminals and socket terminals, if the AC power source is input from the load terminals due to error wiring, the protection device for the socket terminals malfunctions, because the socket terminals are connected directly with the load terminals, but users do not know that, and safe risk may occur.
To solve the problems above, some circuit protection devices are designed to provide a manual test button and a manual reset button. The manual test button can test electrically whether the circuit protection device works properly, and the reset button can perform mechanical resetting for the protection device. But when the protection device fails and the protection function is lost, and the failure protection device cannot be tripped manually by the user, the AC power source connected to load terminals and socket terminals cannot be interrupted in time. On the other hand, the failure protection device can be reset by the user, and also safe risk may occur.
To solve the problems above, some circuit protection devices are provided with a circuit interrupter which can be connected respectively with load terminals and socket terminals, and the load terminals can be isolated from the socket terminals, to prevent from causing socket terminals energizing when the AC power source is input to the load terminals due to error-wiring. However, the design shall be provided with several contacts on one actuator, and that leads to imbalances of loads at different contacts. In addition, in some laboratory application, multiple sets of instruments are connected respectively to load terminals and socket terminals. If the above method of supplying power by multiple sets of contacts is adopted, when one or more contacts occurs poor contacting or disconnecting, the synchronization of power supply will be influenced, and users do not know that at this time, and the performance of power supply system is degraded.