3 phase motor running backwards wire colours

will_505 · Oct 16, 2023

Hi all. Yesterday I wired in my 3 phase compressor to run off our 53kva generator. I just need to know which colour cable is for which phase as I'm not sure.
Cables I've got are: brown, blue, black and green/yellow.
I've currently got brown wired into live 1, blue into live 2, black into live 3 and green/yellow into the neutral/ earth pin. Just to clarify its only a 4 pin plug I have. I have a suspicion the motor is running backwards as the compressor just doesn't sound right at all. Have I wired this plug up correctly?
Any help is appreciated cheers.

will_505 · Oct 16, 2023

Just to clarify this wiring is the wiring that comes out of the compressor to the plug...

marconi · Oct 16, 2023

The positive phase sequence is L1 Brown, L2 Black and L3 Gray. Is the blue colour you mentioned actually gray?

See:

https://www.tlc-direct.co.uk/Technical/DataSheets/Cable/CableColoursLeaflet.pdf

post a picture of the plug Connections. The thickest pin is for the earth not neutral so you connect green/yellow to it.

Study this carefully:

Industrial Extension Leads ltd - https://www.industrialextensionleads.co.uk/plug--connector-types-explained-4-w.asp

westward10 · Oct 16, 2023

The colours tally with it being a flexible cord.

will_505 · Oct 16, 2023

marconi said:
The positive phase sequence is L1 Brown, L2 Black and L3 Gray. Is the blue colour you mentioned actually gray?

See:

https://www.tlc-direct.co.uk/Technical/DataSheets/Cable/CableColoursLeaflet.pdf

post a picture of the plug Connections. The thickest pin is for the earth not neutral so you connect green/yellow to it.

Study this carefully:

Industrial Extension Leads ltd - https://www.industrialextensionleads.co.uk/plug--connector-types-explained-4-w.asp

Please see photos attached of the wires I have in the plug. It's entirely possible I've gotten it wrong. Or I may be colourblind!

will_505 · Oct 16, 2023

will_505 said:
Please see photos attached of the wires I have in the plug. It's entirely possible I've gotten it wrong. Or I may be colourblind!

Just to clarify I did make the wiring a bit neater where it goes into the pins lol

marconi · Oct 16, 2023

will_505 said:
Just to clarify I did make the wiring a bit neater where it goes into the pins lol

You've done what I often do - forget to attach the images. Welcome to my club. Current membership now stands at 2.

marconi · Oct 16, 2023

The cable in use clearly as you said has a blue conductor which is being used as a the L3 phase conductor - normally identified by gray colour.

I take at face value you have tidied up the exposed copper connections.

It would be best if you could mark up the blue conductor to identify it as L3, by applying gray sleeving, brown sleeving with L3 written on it or any tape folded over it with L3 written on it.

Does compressor now function?

will_505 · Oct 16, 2023

marconi said:
The cable in use clearly as you said has a blue conductor which is being used as a the L3 phase conductor - normally identified by gray colour.

I take at face value you have tidied up the exposed copper connections.

It would be best if you could mark up the blue conductor to identify it as L3, by applying gray sleeving, brown sleeving with L3 written on it or any tape folded over it with L3 written on it.

Does compressor now function?

Hi yes I did tidy it all up I just put it together to show how I had it set in the first place. Not with the machine at the moment but, the blue wire in the photo should be in L3, brown should be L1 and black should be L2 correct?
The machine did function the way I had it to start with I was just convinced it was running backwards as didn't sound like any of my other compressors ever have lol..I'm away ATM but I will wire it in the following way: blue: L3, brown: L1, black L2.
Cheers

James · Oct 16, 2023

The important thing to do is to physically check the direction of rotation is correct.
many compressors will still produce compressed air if running backwards but often the oil pump won’t work.

Mike Johnson · Oct 17, 2023

This may help the discussion: How many phases? And another Lucien grumble: 'Amps Per Phase' - https://www.electriciansforums.net/threads/how-many-phases-and-another-lucien-grumble-amps-per-phase.207518/

To reverse phase rotation don't you just swap two of the phase leads?

James · Oct 17, 2023

Mike Johnson said:
This may help the discussion: How many phases? And another Lucien grumble: 'Amps Per Phase' - https://www.electriciansforums.net/threads/how-many-phases-and-another-lucien-grumble-amps-per-phase.207518/

To reverse phase rotation don't you just swap two of the phase leads?

Yes is the short answer, 3 phase motor, swap any 2 phase leads and it will change direction.

westward10 · Oct 17, 2023

Assuming it is actually running in the wrong direction which may not be the case. There could be an issue with the generator.

gordy ere · Oct 18, 2023

James said:
The important thing to do is to physically check the direction of rotation is correct.
many compressors will still produce compressed air if running backwards but often the oil pump won’t work.

Swap the blue and black wires over this will reverse the moter