[sasi behe]

What is the uses of dol starter for industrial purpose?

[sathe1963]

Basically, a starter consisting of a contactor and overload relay. Over load relay protects the motor on overload depending on the settings done. Major part played by starter is because of its no volt coil. If any time supply fails... motor gets off... due to no volt coil contactor gets off... which only could be put on by pressing start button after resumption of supply... thus inadvertent starting of motor is avoided.

[I Newton]

Highest starting torque
Cheapest type of starter

This is the main reasons a DOL starter would be used.

BUT the size of the motor may well make the starting torque produced by a DOL to be too much and very likely damage what the motor is attached to.

You also have the problem of extremely high starting current with starting motors on DOL.

This can cause a problem with electrical items on the same line as the motor as the voltage will drop and even the contactor for the motor itself may lose enough voltage that the contactor drops out.

The high current also means dangerous heat produced in the windings of the motor which dramatically reduces the working life of the motor.

So, DOL is cheap and high torque, but very taxing on the equipment and circuit.

[gajjarvraj]

Why
Wiring diagram needed in D.O.L. motor starter?

[tkrussell]

So the installer knows how the unit is wired internally, and how to connect to building wiring.