The new DC system insulation monitoring device based on phase differences of magnetic modulation

According to the exiting issues of currently DC system insulation monitoring device, this paper developed a more comprehensive function monitoring device. The device adopted phase different of magnetic modulation detection principle. Though access to the unbalanced grounding relay, it can solve the conventional devices which unable to detect issue like: the DC system grounding simultaneity or equivalent insulation deterioration, with this method the device can determine a variety of ground failure correctly, and it also can predict the insulation decline. Because the 500kV transfer substation exiting serious electromagnetic interference which can make the data of insulation monitoring device inaccurate and work unstable. According to these phenomenon, we use a variety of anti-jamming measures on both hardware and software. This paper describes the overall hardware of the device composition and a detailed description of key technologies. Field experimental results show that the device may change from time to time to monitor the insulation resistance and have the ability to find out the grounding branches accurately; also it has no effects on disturbed capacitance. Currently, the device has been putting into use and working well.