When a motor is switched on, there is a high inrush current from the mains which may, especially if the power line section is inadequate, cause a drop in voltage likely to affect receptor operation.

There are several starting systems which differ according to the motor and load specifications.

The choice is governed by electrical, mechanical and economic factors.

The kind of load driven is also important in the choice of starting system:

• Direct On-line starting
• Star-Delta starting
• Part Winding Motor Starting
• Resistance Stator Starting
• Autotransformer starting
• Slip ring motor starting
• Soft starter starting/slackening
• Frequency converter starting