Two Speed Async. Motor

[jan1977]

Need some hints on how to build a two-speed starter.

 

Am I correct here? :

(Fan/440V/12,5A High speed)

 

The wiring of the starter is very much alike star/delta starting; 3 contactors are needed, but 2 O/L relays.

Main contactor needs to have an O/L relay for low speed, and during low speed the star contactor will be closed.

For high speed I will open the star contactor, and close the "delta" contactor, which also needs an O/L relay.

 

Is it this simple? Only difference would be the 2nd O/L relay - or do i need the 2nd at all?

I assume its a single-winding motor.

 

If we have a 2-winding motor, how should I wire this?

 

Jan

 

Need some hints on how to build a two-speed starter.

 

Am I correct here? :

(Fan/3phase/440V/12,5A High speed)

 

The wiring of the starter is very much alike star/delta starting; 3 contactors are needed, but 2 O/L relays.

Main contactor needs to have an O/L relay for low speed, and during low speed the star contactor will be closed.

For high speed I will open the star contactor, and close the "delta" contactor, which also needs an O/L relay.

 

Is it this simple? Only difference would be the 2nd O/L relay - or do i need the 2nd at all?

I assume its a single-winding motor.

 

If we have a 2-winding motor, how should I wire this?

 

Jan

[marke]

Hello jan1977

Welcome to the forum

 

The Dahlander motor can be connected for high speed and low speed where there speeds change by a ratio of two to one, i.e. 4 pole 8 pole.

 

There are several configurations depending on the torque requirements of the motor at the two speeds.

 

In one configuration, the motor is configured as a star - double star with the double star connection at high speed (Main Hi contactor and star contactors closed) and the Main low speed contactor closed for low speed.

 

In another configuration, the motor is wound as a delta double star with low speed in double star and high speed in delta.

In this configuration, the Main Low and star contactors are closed for low speed and the main high speed contactor is closed for high speed.

 

You need to know the correct configuration for the motor that you have.

 

Best regards,

Mark.

[marke]

For more information, see http://www.lmphotonics.com/InductionMotor/...ander_motor.php

 

Best regards,

Mark