It is found through the fault analysis of capacitive voltage transformer（CVT） that such min fault of the CVT as partial damage of capacitor

short circuit of electromagnetic unit and ferromagnetic resonance can be reflected through

to a certain extent

the secondary voltage variation.Therefore

it is necessary to

with combination of faults of various instrument transformers which is found during the daily production work

study deeply the variation rule of waveform during the development of CVT transient faults

use the waveform feature as the basis for monitoring and discriminating the potential fault of the transformer and discover the CVT defects in time to ensure the safe and stable operation of the system.In this paper

the reason of the fault of 500 kV CVT is analyzed deeply by way of disassembly combined with abnormal rise of fault recording voltage with more than 2 times due to the defect of the CVT and eventually leading to secondary voltage disappear.The recording waveform is reproduced by the simulation calculation so to define the transient waveform feature and corresponding detect type and the conclusion can be used to provide a basis for the monitoring of the operating state of the transformer and the determination of the cause of the defect.