Electro dynamic services offers dynatork brand variable speed dc drives. In auto transformer rectifier control panel type dc drive; variable dc voltage is obtained by rectifying continuously variable ac output voltage of an autotransformer. The ac voltage can be changed by manual rotation of autotransformer or by push button operated pilot motor mounted on the auto transformer. In this open loop control system, variable dc voltage supplied to the dc motor changes the speed. This simple yet reliable system is extensively used in the industry.
