A DOL 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 DOL motor starters are available for motors less 
than 150 kW 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 autotransformer starter, star-delta starter or 
resistor starter. Now-a-days VVVF drive used extensively 
for speed control serves this purpose also.