A practical winding fault detector for power transformers

Abstract

In this paper, a new method for detecting internal winding faults for both single phase and three phase power transformers is presented. Not only the winding faults (including phase and ground fault combinations) are covered, but those turn-turn ones are successfully detected as well. These turn-turn conditions represent a basic challenge for conventional differential protection schemes. Internal high impedance ground faults are also covered successfully with a wide range of fault resistance value. The discrimination between winding faults and the magnetizing inrush conditions is also verified. The performance of the proposed detector is investigated using EMTP simulation covering a variety of operating conditions. All applied test results verify the performance of the proposed detector for power transformer protection.