Electronic Circuit for Reduction of Power-On Transient Current in Transformer

This paper describes a simple electronic system that allows reduction of the power-on current in a transformer. When the transformer is connected to the network, a transient current is generated, which is many times greater than the operating current of the transformer. This transient current causes problems in distribution systems, generates disturbing signals for sensitive electronic systems, and can even cause power outages. The transient current can be reduced in various ways, which are sometimes based on transformer modifications. This work presents a method that enables the elimination of a large transient current by a suitable switch-on time of the transformer in relation to the time course of the mains voltage. However, it is also necessary to always switch off the transformer at the same time due to the course of the mains voltage. Although this method is known, no practical solutions are given. The method described here is based on an electronic system and can be used for any transformer without any modification of the transformer. The electronic system was implemented and the measured results are presented.