Rex Power Magnetics

Motor Starting Autotransformer

Motor starting autotransformers

Motor starting autotransformers are a special transformers used in the autotransformer starting of a industrial motors. Autotransformer starting of motors is used widely in starting large industrial motors due to its advantage of providing the highest starting torque with lowest starting line current compared to other reduced voltage starting methods. The reduced voltage taps of the motor starting autotransformer are used to reduce the starting current of the transformer. Contactors switch between the taps, incrementally, increasing the votatge applied to motor as it gets up to speed, while ensuring the starting current is limited. Once the motor reached rated speed, the autotransformer is removed from the circuit entirely, avoiding any unnecessary energization losses..