Single phase inverter - Y or Delta? 1

[Morrie]

I run three small conveyors with 0.18 kW 3phase motors. Two of them run from single phase supplies through an inverter (0.75kW), providing variable speed. The new third conveyor runs on 3 phase directly.

I would like to run the new third conveyor from one of the inverters. I recall that it was necessary to change between Y and Delta connection when I first had the inverters installed on the other 2 conveyors.

Can somebody explain which wiring configuration is necessary and whether is is always possible to configure a 3 phase motor in either configuration? The new conveyor is a totally enclosed unit with no terminal block to view.

 

[EEIre]

Normally Induction motors are connected in delta. If there are only three terminals in the terminal box it is most likely that the motor is connected in delta.

Perhaps you could try to find the datasheet based on the nameplate data.

 

[Marke]

Hello Morrie

In the 50 Hz world, it is common for small motors to be supplied as dual voltage motors where they are connected in star for 400 volt operation and delta for 230 volt operation.

Larger motors are usually connected in delta for 400 volt operation. This is to allow them to be star/delta started.
You can not star/delta start motors that are star connected on 400 volts.

Best regards,

Mark Empson

http://www.lmphotonics.com

 

[GGOSS]

Hello Morrie,

Although Marke has already covered it well, the following 'further explanation' may be useful to you.

General Motor Information:

Small three phase motors (upto to 2.2kW and possibly 4.0kW) generally comprise 3 x 230V windings configured in 'star' thus allowing the motor to be connected to a 400V three phase supply.

General Variable Speed Drive Information:

The maximum output voltage of any standard variable speed drive is determined by the maximum input voltage.

A 3-phase 400VAC input variable speed drive will produce a 3-phase 400V output. Motors as described above must be connected in 'star' to ensure windings are not over-voltaged when connected to this type of VSD.

A single-phase 230VAC input variable speed drive will produce a 3-phase 230V output. Motors as described above must be connected in 'delta' to ensure winding are not 'under-voltaged' on this type of VSD. Operating a motor at less than full voltage affectively reduces its kW output. Therefore configuring the windings in 'delta' ensures maximum motor kW are available to you.

Hope the above helps.

Regards,
GGOSS

 

[jbartos]

Comment on the original posting marked ///\\Can somebody explain which wiring configuration is necessary and whether is always possible to configure a 3 phase motor in either configuration?
///Not always, since the power supply voltage or VFD output voltage can make a difference. Please, consult the conveyor manufacturer for any connections you intend to implement. Is there any warranty coming with the new conveyor? If yes, it is very probable that any change you make could impact the warranty.\\ The new conveyor is a totally enclosed unit with no terminal block to view.
///Again, contact the conveyor tech support to avoid any improper input voltage or any improper vfd-motor set integration/application.\\

 

[Morrie]

Thanks everyone for your helpful advice. Now I have some insight into inverters and three phase motors. The conveyor is a secondhand one, so no there is no warranty, but I was able to track down the motor supplier and get some useful input.