When a motor is energized by a full voltage starter, mechanical and electrical problems can occur. Potential mechanical problems include broken belts, gears or couplings or spilt or broken product. Potential electrical problems include deterioration of motor insulation or brown outs causing nuisance problems with other electrical equipment.

A reduced voltage starter helps to lessen these problems by reducing inrush line current and/or starting torque of a motor applied to the drive load. This is done by either reducing voltage applied to the motor during starting or by using only part of the motor windings during starting. 

Siemens manufactures three commonly used electromechanical reduced voltage starters. Each one is designed for specific application requirements and consists of auto transformer, wye-delta and part-winding starters.

Auto Transformer

This type of starter is suitable for a general induction motor and is commonly used for the following applications:

Part-Winding

This type of starter requires a motor with two separate windings and is commonly used for the following applications:

Wye-Delta

This type of starter requires a motor with an externally connected stator and is commonly used for the following applications: