3 phase motor rotation

[milldrone]

DickDV,

I consulted my pocket reference as DickDV suggested. I only find reference for single phase motors,

Same as russrmartin. My copy has the EASA logo on it (copyright 1997), and of course my local motor rewinder's info.

Question for Dick. What year is your copy?

 

[allscott]

3 words...Phase rotation detector

How was it wired before? which way did it rotate THEN? If the motor has been disassembled, (sent to the shop, rewound....) then why did you re-couple the load?... If it HASN'T, then it should rotate the same way it did before. Did someone forget to mark the leads.... or determine rotation BEFORE a rewire?

How did you get into this situation?

On a "very large motor" where disconnecting the load would be a PITA, it would SEEM that extra care would be taken to determine A,B,C, BEFORE you disconnected it..

Like other posters on here, I always uncouple the load and bump the rotation, unless I am the one who disconnected it (in which case it will be well marked) and it hasn't been to the shop.

My 2 cents,

Stationmaster

Jeepers people seem to be jumpy on here lately, probably why I don't post much anymore.

I really don't need people on here questioning my competency, I am very good at what I do.

Craig, If you had actually read my post you would see that I can't turn the motor by hand physically, no way no how. I have a phase rotation meter but it is useless to me for this problem.

Stationmaster, the machine is brand new and came fully assembled. I called the OEM and they bumped it before assembling it but didn't know what the rotation was. If I am unwiring a machine for repair I always mark the wires because even if the wrong rotation isn't critical, I'm too lazy to insulate the joints twice if I don't have too, and time is usually an issue in my industry.

Check your Pocket Electrical Engineering Handbook. NEMA does spec this and it is shown in this Handbook.

Don't have one? Shucks, they're free! Just ask your motor supplier, motor shop, or pipe and wire distributor. They usually are happy to stamp their name on the cover and give them away as promotional material.

The Handbook is published by EASA, Electric Apparatus Service Association. Don't confuse with Ugly Handbook which doesn't have nearly as much motor data.

Thanks, I do actually have one, just never thought to look in it. Instead of sitting in my office and waiting for a response from you guys which I should have done I went down and helped the millwright uncouple it and bumped it. Then reversed the wires and bumped it again.

Ok, what about double shafted motors? And my favorite, when the millwrights swap bearing endbells?

Yes I have been a victim of the endbell swap, scratched my head for a long time on that one because I had marked the wires. After staring at the thing for a long time I realized that the name plate was facing the other direction from when I unwired it. Doh!

I also don't trust a motor that has come back from rewind to be correct. I have been burnt that way too.

Thanks for the replies