Detection of Impaired Property of Varistor by the Harmonic Analysis
Hirosi Komiya, Megumi Sato, Toru Yamazaki · IEEJ Transactions on Fundamentals and Materials · 1999
Varistors are used as surge absobers for high voltage electric power devices.If the varistor absorbs large surge energy, it will be impaired and a resistive leakage current containing 3rd harmonic component caused by nonlineality of the varistor resistance will remarkbly increased.In this paper, a resistive leakage current measuring method using the harmonic analysis is proposed for detection of impaired property of varistor which is in service.It is based on a relation between the phase of the 3rd harmonic component of the current and a phase of the line voltage.A measuring system is composed and tested at a low voltage line.The phase of the line voltage measured by the system agrees well with the direct measured phase of the line voltage.It means that this method can be used for detection of impaired property of varistor which is in service.