Patent ID: 6956726

Claim:
A power protection device, coupled to an alternating current (AC) power source having a hot line and a ground line, the power protection device comprising: a power source switching unit, coupled to the AC power source, for shutting off the AC power source according to an open control signal; a leakage current protecting unit, coupled to the AC power source and the power source switching unit, for preventing a leakage current, wherein the leakage current protecting unit receives a first current values of a current flowing through the hot line and a second current value of a current flowing through the ground line, compares a difference between the first current value and the second current values with a leakage current threshold, and outputs the open control signal if the difference is greater than the leakage current threshold; and an over-current protecting unit, coupled to the AC power source and the power source switching unit, for preventing an over-current at the AC power source, the over-current protecting unit including a current sensor, coupled to the AC power source, for outputting at least one of the first current value and the second current value of the AC power source, an analog/digital converter, for converting the output of the current sensor into a digital signal, an integrator, calculating a power level by integrating the digital signal squared over an integrating time interval, an short-time energy calculator, for receiving the power level to generate a short-time energy by accumulating the power level within a short time interval, a first comparator, for comparing the long-time energy with an abnormal threshold and outputting the open control signal when the short-time energy is larger than the abnormal threshold, a long-time energy calculator, for receiving the power level to generate a long-time energy by accumulating the power level within a long-time interval, and a second comparator, for comparing the long-time energy with a long-time threshold, and outputting the open control signal when the long-time energy is larger than the long-time threshold, wherein the long-time interval is longer then the short time interval.