What is What is Step Down Transformer Step Down Transformer we can say it is a device that converts high primary voltage to low secondary voltage. In this transformer, the primary winding of a coil has numerous turns than the secondary winding. The prime purpose of the transformer is that it reduces the voltage and is used in all household’s electronic appliance. Our life today is heavily dependent on electricity, and thus, we must know about every electrical appliance or devices before we purchase.