1.1 Introduction
A variac is also known as a variable autotransformer, which is a single primary winding wrapped around a magnetic core is used as in the autotransformer but instead of being fixed at some point, the secondary is tapped continuously over the output voltage range. In the construction, a toroidal core was used so as to allow for easy variation of output voltage. All the details that are required to help in constructing the variac to ensure that it gives the desired results were also determined. The appropriate insulation materials as well as the electrical accessories were selected taking the power, voltage and current rating of the variac into consideration. The construction was divided into three segments: magnetic circuit, electrical circuit and casing construction. The magnetic circuit construction gives details of the magnetic core and how it was prepared for winding along. The electrical circuit construction gives details of the whole winding along with insulation and leads termination. The constructed work was tested. The tests carried out include continuity test, insulation resistance test, mechanical and running tests.
As a prelude to other parts of this study, this chapter will discuss the background upon which this study was initiated, the statement of problems that led to this study, the Aim and Objectives of the study. Others are Significance of the study, Scope of work, Limitations of the Study and Definition of technical terms.
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