Resonance overvoltage in power system causes wire breakage and even burning of voltage transformer

but also causes damage of primary equipment large scale of power off and a serious threat to safe and stable operation of power grid. In this paper

the frequent fuse of HV fuse for 10 kV voltage transformer at un-earthing system due to ferroresonance is analyzed on the basis of the study of generating mechanism of the ferroresonance with combination of operation of fault record and secondary harmonic elimination device of 10 kV substation. The control of multiple function harmonic device to the ferroresonance overvoltage of voltage transformer is analyzed with consideration of operation of the harmonic elimination device before and after fault and fluctuation of operation voltage at 10 kV side before and after operation of the device. On the basis of above study

the ability of the multiple function harmonic elimination device in eliminating ferroresonance overvoltage is questioned in this paper

and the reason of its function limitation is analyzed briefly.