Sinopower Transformer (Changzhou) Co. Ltd, Ltd.'s oil immersed transformers are usually double winding transformers, which have two windings on the iron core, one is the primary winding and the other is the secondary winding. They are composed of the iron core, winding, oil tank, oil pillow, insulation sleeve, tap changer, and gas relay.

When an oil immersed transformer is subjected to short-circuit current, a large electromagnetic force will be generated on the winding, causing damage to the transformer. The basic windings have two types: concentric and overlapping. Vacuum oil filtration and oil injection processes are used to minimize the moisture inside the transformer. A non suspended structure is adopted, which can withstand transportation vibrations.