Study On DC System Earth Detecting Device

The shortages of method are analyzed on detecting earth fault of DC system by the principle of electrical bridge balance and frequency conversion in the thesis. It advances a method of synthesis criterion, which detects earth fault with Huoer sensor of the principle of magnetic potential balance and through detecting the positive and negative pole bus voltage, insulation resistance and leakage current. It samples directly DC system leakage current, which need not feed low frequency AC signal to DC bus and the detected earth resistance has nothing to do with the distributed capacitance. In the meantime to achieve the detecting method, hardware circuit, software designs and interference prevention designs are introduced. Experiment shows that synthesis criterion method can detect the DC system earth fault correctly.