Design and Implementation of a 2-kVA, Shell-Type, Step-Down, Transformer

Abstract

Transformer is the heart of a sub-station’s equipment, which primarily transforms voltage from one level to the other at the same frequency. The voltage can be raised (Step-up transformer) or lowered (Step-down transformer), but with a fractional decrease or increase in current ratings. Presented in this paper, is the design and implementation of a 2 kVA, 220/110-kV, core-type transformer. The materials used were copper wire, silicon steel laminations and is air cooled. A comprehensive design calculation of different parts of the transformer was carefully carried out based on some already established basic transformer design assumptions. E-shaped laminations were 109 and the I-shaped laminations were 93. Pre-commissioning tests such as continuity, short and open circuit test were conducted satisfactory. When tested, the efficiency was found to be 93.6% as against the designed value of 96.32%. This reduction in efficiency was as a result of occurrence of losses and heat generated within the transformer. The potential caused of these losses and transformer heating could be attributed to the method of implementation such as the punching of bolt holes and during the cutting of sizes of the metal sheets. The designed transformer finds application in practical classes in undergraduate Electrical Machine Laboratory and domestic use.