Online detection of inter-turn short circuit faults in dry-type air-core reactor

Abstract

Inter-turn short circuit faults are among the common faults occurring in dry-type air-core reactor. This paper presents an online detection method of inter-turn short circuit faults for dry-type air-core reactors by using search coils. Since this type of fault creates shorted turns in which there are high induced currents that can produce intense reversed magnetic field, the magnetic field distribution is no longer symmetrical. The variety of magnetic field from the normal condition to the fault condition can be monitored by search coils. Based on coupled field circuit method, the magnetic field distribution of the reactor and the induction voltage of the search coils are computed in different conditions. The proper mounted positions of search coils are suggested. The proposed method has been verified to be effective and easy for implementation by experimentation.