In order to maintain operational reliability of low-voltage supply system and information system

it is very important to detect the varistor’s condition timely and effectively. In this paper

several types of failure modes of varistor are concerned. According to the research of varistor’s response to combination wave

it shows that the responses vary with the varistor’s failure modes because of the difference in V-A characteristic. Based on the response

the kind of failure modes of varistor could be determined.