In this paper

the faults of discharge coil are classified into three types. Firstly

fault due to self defects（several hours after operation）

secondly

fault due to incorrect use（several minutes after operation）

thirdly

combination fault（during switching period）based on the existing research results and technical standards of current product and also on the fault case of discharge coil for practical reference. Three prevention measure suggestions of the faults from practice experience are adopted by the latest national standard. It is suggested to add such two test items as "Sustaining operation"and "Differential pressure test"

which is helpful in quality assurance of product.