Three-phase autotransformers

Purpose and design

3AT type three-phase autotransformers are a special variety of transformers in which the primary and secondary windings are not separated. Compared to transformers at the same power, autotransformers are lighter but have a much lower short circuit impedance. Autotransformers are used for voltage levels adjustment, powering low-power electrical equipment, motor start up. The winding of an autotransformer may have multiple voltage tap changers. The design of the device provides fixing by means of angle brackets screwed to the core. Upon agreement, autotransformers can be supplied in enclosures with the required protection class.