For studying the reason of ferromagnetic resonance fault in 220 k V capacitor voltage transformer（CVT）

through the discussion of structure principle

internal steady resonance

transient resonance and its suppression measures

and after the analysis of capacitance

dielectric loss and oscillogram

the initial judgment is CVT cause ferromagnetic resonance

and the fault cannot be effectively damped. After the study

the faulty CVT is returned to the manufacturer for accuracy test

ferromagnetic resonance check. The item of ferromagnetic resonance check is unqualified and the correctness of the analysis is verified. Finally

the external condition causing ferromagnetic resonance of CVT and the damping invalidity are summarized

also many suggestions on how to avoid the ferromagnetic resonance of capacitor voltage transformer are proposed.