ABSTRACT
A variac is also known as a variable
autotransformer. 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
result 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