Review on Reduction of Magnetizing Inrush Current in Transformer

Haresh S. Nankani, R. B. Kelkar

Abstract: Transformer is considered as the most important apparatus as heart in electrical transmission and distribution system. When a transformer is first energized, a transient current many times larger than the rated transformer current can flow for a number of cycles. Inrush currents are of very high magnitude generated when transformer cores are driven into saturation during energisation. The worst inrush current happens to flow when the primary winding is supplied at an instant of voltage zero crossing. These currents have undesirable effects such as reduced power quality on the system, loss of life to the transformer itself. To mitigate this magnetizing inrush current, few of the methods are discussed as Controlled switching, sequential phase energization, Asymmetrical winding configuration.

Keywords: Controlled switching, residual flux, transformer switching, sequential phase energization, Asymmetrical winding configuration, Inrush current, power quality