Technological development of on - load tap changing mechanism in power transformer - a review

Voltage control is one of the main concerns of power utilities with regard to quality of the power. To maintain load voltage within permissible limits every power transformer is designed with voltage controlling and regulating system. Hence transformers are required to supply with an On-Load Tap Changer (OLTC) which became mandatory. The OLTC voltage regulation is naturally operated by Changing the number of turns in one of the windings of the transformer. This paper presents a review of a differentiated details of conventional mechanical OLTC and electronic assisted tap changer as controller.