The insulation requirement of the minor winding of power transformer

Abstract

A transformer is one of the key equipment in modern power system. It is used to raise the voltage levels from few kV's i.e. from the generating levels to a very high transmission level of 400kV, 765kV. Higher voltages are important for the efficiency and reliability of the electrical transmission system as higher voltages results in less losses in terms of heat, better voltage regulation and thus raising the power utility at consumers end. Subjecting to such high voltages the power transformers are always vulnerable to high frequency surges generated either by the natural or external causes such as striking of lightning at its leading terminal or self generated over voltages within the system itself by the various switching operations and fault. Thus to avoid failures it is important to have adequate design consideration so that the heavy losses both in terms of economy and power interruption can be avoided. Therefore the insulation design is perhaps the most critical part involved in transformer manufacturing. Keeping these in mind, the work under this paper aims at resolving the problem of minor insulation of large power transformer and arriving at a better design structure thus, achieving a better voltage profile in terms of impulse voltage distribution.