A Monitoring Method of Inter-turn Insulation Fault for Dry-type Air-core Shunt Reactor

In order to solve the problem that the existing protective devices could not cut timely and accurately the dry-type air-core shunt reactor with inter-turn insulation fault, which caused the accident expanding, a new method of inter-turn insulation fault on-line monitoring based on impedance variation was proposed. Circuit model and voltage equations of inter-turn insulation fault were established and numerical analysis method was applied to analyze variation of electrical parameters in different positions. Based on these, impedance variation was determined as the monitored object and the test platform was set up to verify the test. Research results indicate that, total current basically remains unchanged, but real current increases dramatically after inter-turn insulation fault occurs. Equivalent resistance increases and equivalent reactance decreases, the change rule and the magnitude of variation are consistent between equivalent resistance and real current. The test results prove that this monitoring method is true and effective.