Patent ID: 7492559
Filing Date: 2009-02-17
Classification: H01H,H02H

Abstract:
1. An apparatus for testing the life of a leakage current protection device, wherein the leakage current protection device has a first input, a second input, a third input, a fourth input, a first output, a second output, a third output, a trip switch having two LINE terminals that are electrically coupled to the first input and the second input, respectively, and two LOAD terminals that are electrically coupled to the inputs of an electrical appliance, respectively, a reset circuit having an input that is electrically coupled to the third input, and an output that is electrically coupled to the first output, a trip coil circuit having a switching device having a gate, an anode and a cathode, a first input electrically coupled to the output of the reset circuit and the first output, a second input that is electrically coupled to the fourth input, an output that is electrically coupled to the second output, and a leakage current detection circuit having an output that is electrically coupled to the third output of the leakage current protection device, comprising: (i) a microcontroller unit (MCU) having a first input that is electrically coupled to the second output of the leakage current protection device, a second input, a third input that is electrically coupled to the output of the leakage current detection device and the third output of the leakage current protection device, a first output that is electrically coupled to the third input of the leakage current protection device, a second output, a third output, a fourth output that is electrically coupled to the second input of the trip coil circuit and the fourth input of the leakage current protection device, and a power supply input P; (ii) a power grid signal synchronization monitoring circuit having an input that is electrically coupled to the first output of the leakage current protection device, and an output that is electrically coupled to the second input of the MCU; (iii) an alarm circuit having an input that is electrically coupled to the third output of the MCU, and a power supply input; (iv) a power supply circuit having an input that is electrically coupled to the first output of the leakage current protection device, and an output that is electrically coupled to the power supply input P of the MCU and the power supply input of the alarm circuit; and (v) a ground fault simulation unit having an input that is electrically coupled to the second output of the MCU, a first output that is electrically coupled to the first input of the leakage current protection device, a second output that is electrically coupled to the second input of the leakage current protection device, wherein, in operation, the power grid signal synchronization monitoring circuit generates a first signal synchronized with an AC power from the first input and the second input of the leakage current protection device to form a power grid signal synchronization signal electrically coupled to the second input of the MCU; the MCU generates a pulse signal when the power grid signal synchronization signal reduces to a first predetermined threshold value during every positive half-wave of the AC power, and a second signal from the second output to the ground fault simulation unit to generate a simulated ground fault signal; the leakage current detection circuit generates a third signal in responsive to the simulated ground fault signal and the pulse signal, which is input into the third input of the MCU; the gate of the switching device receives the pulse signal to turn the switching device into its conductive state during the pulse period; and the MCU receives a DC voltage at the first input of the MCU, and compares the DC voltage with a second predetermined threshold value to determine whether a fault exists in the leakage current protection device, and activates the alarm circuit if the at least one fault exists.