In this paper

the defect of over heat in 220 kV capacitor voltage transformer（CVT） is introduced The defect type and location are confirm by the infrared thermometry

the reason of the defect is analyzed by way of high voltage test and disassembly at the factory and its correctness is verified. At the same time

in view of such factors as historical operation data and the situated environment etc. of the substation equipment the comprehensive fault diagnosis system is proposed based on the fusion features

so to keep it find and diagnose fault of the equipment more accurately and efficiently and assure safe operation of the equipment.