Need Help!- changing 380 V motor to 220 V

[MaNo]

An air compressor to operate in conjunction with my CNC router was shipped by error with 380V motor. Factory has sent a step-up transformer which will arrive today.

Yesterday, however, I had an electrician here and he wondered why the factory sent a step-up transformer when all it takes is to change the connection to the motor to run on 220V. He mentioned something like changing 'parallel' to 'delta'. This link is photo showing factory wiring.
http://dl.getdropbox.com/u/2043845/380%20motor.jpg

Question I have....is the man wet or does he have a point?

I do have a step-up transformer now but why install it if it's not necessary?

Any info would be appreciated.

[jalessi]

Take a look at this, it may help.

http://www.usmotors.com/products/ProFacts/1-120-7.htm

Jeff...

[MaNo]

Originally Posted by jalessi Take a look at this, it may help. http://www.usmotors.com/products/ProFacts/1-120-7.htm Jeff...

Thanks for link, Jeff, it looks....hmmm.....kinda Greek to me but will let the electrician have a look at it.

What may complicate the issue is the fact that my 3-phase 220 V is generated by a rotary phase converter.

[langwadt]

Originally Posted by MaNo Thanks for link, Jeff, it looks....hmmm.....kinda Greek to me but will let the electrician have a look at it. What may complicate the issue is the fact that my 3-phase 220 V is generated by a rotary phase converter.

shouldn't matte it is still three phases.

when connected in Y each coil see the voltage from a phase to the midpoint
which is, if everything is balanced, the same as neutral. So it sees 220V

when connected in delat each coil see the voltage from one phase to another phase. So it sees 380V

-Lasse

[Zig]

Looking at the photo Your moto is a 3 phase motor connected in STAR.

If you were to change the connections into DELTA configuration it would quite happily hum ( sorry that hould be RUN) at 220V 3 phase.

[MaNo]

Thanks Lasse and Zig. I have added the wire identifications to the image as they are now (factory wiring for 380V)

http://dl.getdropbox.com/u/2043845/380%20motor.jpg

Is that still a Star (Y) or is it now something else. Can this still be changed to Delta?

[Al_The_Man]

I think you will find that removing the horizontal link bar and placing three vertical links on each of the 3 sets of terminals will connect it in delta.
The incoming 3 phases will each go to a vertical link.
Al.

[jalessi]

Connect U2, V2 and W2 together (Star point). Connect phases to U1, V1 and W1

[jalessi]

Sorry Al,

I was posting the same time as you where.

Jeff...

[jalessi]

Al,

Please confirm this diagram is correct.

Jeff...

[Al_The_Man]

Yes the left side, Delta, was as I outlined in the above post.
Motor manuf. usually terminate the coil ends to make it easy to link for either Star or Delta.
Al.

[jalessi]

Mano,

Do you understand Al's instructions and the diagram?

Jeff...