Star/Delta Starter

It depends on the acceleration time.

please give me any link related this or explain clearily.

tnx

Try www.my electrical.com/stardelta motor starting time

There is a precise formula for calculating the acceleartion time of a motor driving a particulat kind of load, which takes into account, the starting torque developed by the motor, the GD2 of the motor, the GD2 of the connected load, etc.

The acceleartion time definitely depends upon the type of connected load. For example, a centrifugal pump might accelerate in about 8 seconds whereas a centrifugal blower would need about 20 to 30 seconds or even more time to accelerate.