Investigation of magnetizing inrush current in a single-phase transformer

The magnetizing inrush current which occurs at the time of energization of a transformer is due to temporary overfluxing in the transformer core. Its magnitude mainly depends on switching parameters. A system for measuring the inrush current is described. The system is also capable of presetting various combinations of switching parameters for energizing of a transformer. Data sampling of the magnetizing inrush current has been achieved by using a microcomputer, and a software package has been developed to perform harmonic analysis of each of the first few transient current cycles. The effects of the remanent flux density, the switching angle, and the primary winding resistance on the magnetizing inrush current of a 2.5-kVA single-phase transformer are presented.>