Study on state judgment method of metal oxide arrester without gaps in AC power system

In this paper, the AC and DC test platforms are set up to study the change regularity of MOA characteristic parameters with various factors and typical faults by online and offline detection methods. The sensitivity and uniqueness of the characteristic parameters are summarized and analyzed to determine the state of MOA or varistors. The test results show that the resistive fundamental current is the most sensitive to the environment temperature and it increases about 2.27 times when the temperature changes from 20 C to 80 C. The resistive fundamental current is also the most sensitive to the change of MOA surface state and it increases about 1.52 times when the equivalent salt deposit density of surface is 0.06mg/cm
²
, but the DC leakage current is also very sensitive and it increases to 72.0μA. The characteristic parameters change a little after the deterioration test of MOA. The DC reference voltage is the most sensitive to the overvoltage deterioration of MOA and it decreases 6.4% when part of MOA is in the state of severe deterioration. Based on the test results, a qualitative state detection method is put forward.