Transformer types include the autotransformer and the isolation transformer.

The self-coupled structure is simple, cost-effective, and shares input/output and neutral lines. It uses a single winding for both primary and secondary sides, with an electrical connection, but has poor safety performance.

Isolation-type structural materials are abundant, resulting in higher costs. Besides changing the voltage, they also electrically isolate the input and output windings, as well as the neutral wire, to prevent the danger of simultaneously touching live components (or metallic parts that may become live due to insulation damage) and ground. Additionally, isolation transformers have the function of suppressing various interferences, possess filtering capabilities, and offer high safety.