The AC filter arresters frequently operate in use. It's core component

ZnO varistor

shows aging phenomenon in case of multiple impulse currents. While

the variation of AC/DC reference voltage and leakage current of ZnO varistor are closely related to the impulse current amplitude

impulse current waveform

number of impulses and interval time. In this regard

the variation of the AC and DC V-A characteristics of the ZnO varistor under 8/20 μs standard lightning impulse current with single group of 2 impulses and single group of 20 impulses are compared and analyzed. The test results show that for either DC V-A c

haracteristics or AC V-A characteristics

the influence of aging phenomenon of the ZnO varistor is more obvious under single group of 2 impulses than under single group of 20 impulses. In addition

when the DC reference voltage

U

1mA

drops to the value of 5%

the leakage current

I

L

at 0.75

U

1mA

is much smaller than 50 μA

namely

I

L

is deficient in characterizing the aging state of ZnO surge arresters independently；while the resistive component amplitude of the leakage current under continuous operation voltage shows linear upward trend with the number of impulse groups which

as an on-line monitoring and evaluation indicator

can well characterize the state of impulse aging

and the variation rate of it is about 70.6% when the variation rate of

U

1mA

is 5%.