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Need help hooking up Polyphase motor

Forrest Silas

Aluminum
Joined
Mar 31, 2005
Location
Clanton Alabama
I am trying to get a Colchester lathe with a 3hp Polyphase motor running. The seller said he was running it on 480, and I need to change it over to 240. The tag on the motor says 220 - 240/ 400 - 420 so I believe it can be run on 240.
There are six leads from the motor labeled A1, A2, B1, B2, C1, and C2. A1, B1, and C1 are tied together. The other three are each connected to a line. What would be the correct combinations for the lower voltage?
Thanks,
Forrest
 
Forrest,

I really want to validate my Mensa membership, but I can't find any dope on the connections you indicate. Even IEC connections don't have A-B-C numbering.

I'm too dumb to extrapolate the NEMA wire numbers to your A-B-C system, so maybe one of the retired X-spurt electrical types will pop in and give us the benefit of their (hands on!!) knowledge.:)

Stuart
 
A b and c are most likely the winding names. Just to be sure disconnect the 3 wires which are tied together and measure the ohms of A1 A2, B1 B2 and C1 C2 they should read close to zero,

The motor sounds like it is connected in star (wye) which is what a 415V 50 Hz English motor would be quite happy with running off a 480V 60 Hz supply.

Now you want to connect it delta which will make it a 240V 50 Hz motor or a 277V 60 Hz motor, it will still work on 240V 60 Hz but it will produce less than rated torque.

Here goes connect A2B1, B2C1, C2A1, These 3 connections go to L1 L2 L3 or whatever the line is called in the US.

If you look in the terminal box lid it usually shows how to install the links to get either star or delta connection.
 
Heli hit it...

Helical hit the nail on the head.

Do look for the diagram- if it doesn't look like a wiring diagram, it may just look like letters and numbers in groups.... with one identifying high voltage, the other identifying low.
 
Glad it worked for you, we have the same electrical system as England here in Australia so I have seen motors like that before except we rarely use the 240V connections as the 3 phase supply here is 415V.
 








 
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