There are several types of power transformers, primarily categorized based on their design and application. The main types include step-up transformers, which increase voltage levels; step-down transformers, which decrease voltage levels; and isolation transformers, which provide electrical isolation between circuits. Additionally, there are auto transformers, which have a single winding that acts as both primary and secondary, and three-phase transformers, used in three-phase power systems. Each type serves specific functions in electrical power distribution and transmission.