How to select Star - Delta starter for a motor

What is your motor rated power (KW) and what are the load your motor is driving? You should provide more information if you want some answer.

Hi, Dear Simon,

Thank for the reply. The details are as follows;

Power = 15KW

Voltage 380V, 3-phase, 50Hz

RPM = 970

This motor will be used for a Winch which is used to pull small boats.

Regards!

For selecting a star-delta, you should consider the control voltage for energizing your contactor, indicator lamp, timer and others devices that needed in your star delta starter control system

The timer should be from 1 to 20 second time scale, as it may take about 7 to 13 second to change over from star point to delta point, depending your driving load.

For example, if your Winch can able to speed up to 60% or 70% of the rotation during the initial star point starting, (within 7 or 8 second) then, your timer should be adjusted accordingly so that your starter can changer over to delta point for full power.

Your motor must have 6 terminal for the connection for the star delta starter

Make sure that your motor is design for delta connection and not star connection, other wise your motor will burnt out.

When doing motor connection to the start-delta starter, you must observe the motor winding U1, V1, W1 and U2, V2, W2. and make sure the head of the winding and the tail of the winding are not mix up.

After all the connection is completed, you got to manual test the rotation of the motor between the star point and the delta point and ensure that both rotation are in the same phase direction.

WHEN THE MOTOR RATED POWER I0 KW OR MORE THAN YOU SHOULD USE STAR -DETA STARTER FOR THE MOTOR AND THIS AS GENERAL

In general, under the IEE regulation it is stated that any motor higher than 13HP or 10KW, star delta starter should be apply for the starting of these motor.

Starting a motor more than 10 KW does not necessary to used star delta. It all depend on the load that your motor is driving and the incoming power supply capacity that you have in your plant.

I have a 18KW motor that couple with a hydraulic coupling to drive a gear box. After understanding the basic function of the hydraulic coupling system, we use a direct on line starter (DOL) to start the 18KW motor and it working fine.

Was an easy answer, you have a relatively low RPM, go with Delta. You need amps at low RPM, delta will give you that.