Residual Magnetic Flux ofOn-LoadTransformer for Controlled Switching

摘要

When a transformer is being energized, a large magnetic inrush current flows depending upon the closing phase angle of the circuit breaker and the residual magnetic flux in the iron core. One of the suppressing methods of the magnetic inrush current is to control the closing phase angle of the circuit breaker. Controlled switching has been used for no-load transformer energization until now. However, the transformer may be switched under an on-load state. In this case, a large magnetic inrush current will flow. To suppress the inrush current by using controlled switching, the information of the residual magnetic flux in the iron core is needed. The residual magnetic flux for no-load transformers has been investigated. However, the residual magnetic flux for on-load transformers was not investigated. In this paper, the residual magnetic flux for an on-load transformer was investigated by experiments and calculations. (c) 2020 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.