SONET's SM-III motorized change-over switch is required in application where the transfer must be done quickly after source failure. There is no need for manpower in transfer process, this means that the equipment can be installed in isolated area or place. Motorized change-over switch includes two breakers and a motor operator device. Switch can be operated either electrically by using motor operator or manually by using the local handle. The control can easily be prevented by a toggle switch "Auto/Hand" on the motor operator. This insures that maintenance work can by executed safely. SM-III 3P & 4P covers the range from 100A to 1250A 3 & 4 pole.