This invention may be suitable to an autocoupling reduced voltage starter which uses the three-phase, squirrel-cage induction motor as reduced voltage starting. For general reduced voltage starter, the main circuit must be cut off while the starter changes from starting state to full voltage running, so the problem of secondary surge current occurs. This invention offers an autotransformer with secondary windings and a group of contactors. The starter can change into full-voltage running without cutting off the main circuit. Therefore, the secondary surge current can be eliminated and there is no any power loss while full-voltage running. |