Reduction of magnetizing inrush current in power transformers

Stability and security of the transformer protection are important points to system operation. Transient currents caused by the transformer at the time of energization can produce mechanical stress to the transformer, causing damage to transformer windings, and may cause protection system malfunction. It often affects the power system quality and may disrupt the operation of sensitive electrical/electronic loads such as computers, medical equipments and adjustable speed drives (ASD) of the industry. It may also cause inadvertent operation of transformer protection relays (e.g. differential relay). Looking into above matters, reduction and the way to control of transformer inrush currents have become important concerns to the power industry