STAR DELTA connection Diagram and Working principle Descriptions: A Dual starter connects the motor terminals directly to the power supply . Hence, the motor is subjected to the full voltage of the power supply . Consequently , high starting current flows through the motor . This type of starting is suitable for small motors below 5 hp (3.75 kW) . Reduced-voltage starters are employed with motors above 5 hp. Although Dual motor starters are available for motors less than 150kW on 400 V and for motors less than 1 MW on 6.6 kV . Supply reliability and reserve power generation dictates the use of reduced voltage or not to reduce the starting current of an induction motor the voltage across the motor need to be reduced. This can be done by 1. Autotransformer starter , 2. Star-delta starter or 3. Resistor starter . Now-a-days VVVF drive used extensively for speed control serves this purpose also.