Study of High Voltage Inductive Voltage Transformer for Transients and Ferroresonance

Inductive voltage transformer (IVT) is an instrument transformer which is used for measurement and protection in power system. Insulation plays a vital role in reliable performance of IVT. Occurrence of partial discharge (PD) due to high voltage stress on winding reduces life of insulation and adversely affects the performance of IVT. Modern power network involves many power electronic devices which create distortion in signals of various frequencies. To increase the withstand capability against the harmonics occurred due to transients, proper design of IVT is needed. Initiation of transients can lead to occurrence of ferroresonance, as IVT has nonlinear characteristics; it has chances of causing ferroresonace with capacitance present in power cables in transmission network. This results into overvoltage and over-current in the network. Mitigation of ferroresonance is important to protect the equipments from damage. This paper deals with the detail study of IVT to which oil impregnated paper (OIP) is used as insulation, its fundamentals of design, construction and survey of mathematical models for ferroresonace and transients which impact the performance of IVT.

I. Introduction

Transformers used for metering and protections in power system are called as instrument transformers. Voltage transformers are classified into two types: •

Inductive voltage transformer (IVT).

•

Capacitive voltage transformer (CVT) [1].