In this paper

the fault location analysis

comprehensive judgment and test method are introduced through one secondary voltage loss fault of a 220 kV capacitor voltage transformer（ CVT）. The faulty CVT is specifically judged comprehensively by on-line monitoring data

electrical test and test method of insulation oil so as to determine the fault type and fault location quickly and accurately which makes the effective fault treatment. The reason of the fault is analyzed through specific data of site test and inspection as well as disassembly condition

the measures on preventing such similar fault are raised and improvement suggestions on the manufacture and process of CVT are given.