Yes, DOL starter could be used with your variable speed induction motor. As torque would be less for higher speed than at lower, for keeping the KW rating same.

yes it can be run by DOL Starters. Variable speed drive is being used for speed variation purpose and starting purpose through voltage boost as well, but DOL Starter can be used with Induction motors too.

HERE IS THE REASON WHY?

If large rating induction motors are connected directly to the supply, a heavy starting current can damage the motor and also cause disturbance of voltage, just like voltage dip on mains supply hence malfunctioning of other equipments connected to the same supply.

This is the reason why DOL starters are limited to small rating motors where distribution system (mains supply) can withstand high starting currents without excessive voltage dips.

For a large rating motor, ranging from 5 HP to 25 HP, oil immersed DOL starters are used which provides insulation against sparking on contact points and hence increases the life of starter.

DOL starter consists of MCCB, contactor, and overload relay. It acts as a switch under normal working condition by providing the means to switch ON and switch OFF the motor.

It holds the switch ON condition when motor is running by the use of latch mechanism and interrupts the flow of current to the motor once the stop button is pressed.

The popular issue associated with DOL starting of large IMs is the possible consequence problematic voltage sags (or dips) that may extend up to the PCC. In addition, the motor itself suffers from relatively high electromagnetic and electromechanical stresses during the starting process. Since, the manufacturer mandates the use of VSDs, then it is rational to be careful to start them in DOL mode. The motor design may be unsuitable for DOL from inherent capability point of view.

yes; but under one condition the rated frequency of motor equals to 50 HZ (or 60 HZ). it should be highlighted that some motors which drive by

variable speed drive may be designed at rated frequency differs from supply meanwhile its frequency is more 50 HZ.

If your motor has a small rated power, you also can test it using an autotransformer as a DOL starter. In this case you must increace voltage at a slow pace. We usually test our DOL motors with the autotransformer start, in order to avoid torque sensors overload.

Thank you so much for all of you for sharing useful information.

It depends on the motor type/order number! Some induction motors are specifically designed to run on frequencies other than 50/60Hz and consequently other voltages than the standard grid voltages! e.g. induction servo motors used as spindle drives that would be destroyed if connected to the grid!

So I believe the motor order number and manufacturer recommendations should be investigated and followed as much as possible!