A New Passive Fault Indicator For Locating Insulator Flashover

With the rapid development of economy in china, the scale of power network is more and more big, structure is increasingly complex, and high reliability of power supply is required by users. On the one hand, faults should be prevented during normal operation of power system; On the other hand, faults must be located and removed rapidly, thereby the loss can be minimized.In our country, the rate of trip-out caused by insulator faults occupies 60% of the total trip rate, insulator faults cause serious threat to the security of transmission network and distribution network, while the fault alarm problem of insulator cannot yet be well solved by existing technology, moreover flashover and breakdown of insulator may cause various short circuit or grounding faults, and the faults location problem need to be solved, especially the single-phase grounding fault of distribution network. At present, most blackouts that power consumers suffered were caused by faults of distribution network, according to statistics, single phase-to-earth fault was the one occurred most easily in distribution network, accounted for 80% in total, meanwhile, the equipments and system security may be destroyed by arc-grounding overvoltage that caused by single phase-to-earth fault. and compared with transmission network, the single phase-to-earth fault location of distribution network is more difficult, and it is still a problem which is unsolved by the recent distribution automation terminals. Therefore, the solution to the location for insulator which is flashover or breakdown and single phase-to-earth fault in distribution network based on automatic method are very important to improving reliability of power supply.According to the deficiency of existing insulator detection, grounding fault location methods in distribution network and distribution automatic terminals, a new passive automatic indicator for the grounding fault caused by insulator flashover was designed in this paper. The nano-crystalline power supply coil of passive indicator can get power from fault current flowing through the end of insulator or the earthing point of tower, then the indicator will store the power, so the grounding fault can be located by it based on msp430 and wireless module without its own power. This kind of passive indicator is low cost, stable and accurate. The results of experiments show that minimum running current of the indicator is only 210mA, and the indicator can bear high current impulse, so the single-phase grounding fault and multi-phase grounding fault caused by insulator flashover can be located by the device. Therefore, it's applicable to different types of neutral ground in power transmission and distribution systems.