Contact US

Log In

Come Join Us!

Are you an
Engineering professional?
Join Eng-Tips Forums!
  • Talk With Other Members
  • Be Notified Of Responses
    To Your Posts
  • Keyword Search
  • One-Click Access To Your
    Favorite Forums
  • Automated Signatures
    On Your Posts
  • Best Of All, It's Free!

*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

Students Click Here

Induction motor stator orientation

Induction motor stator orientation

Induction motor stator orientation

Hello Engineers,
We just received a new 200kW 4P induction motor. Due to machine space restriction the MTB needs to be on other side of the motor. The motor terminal box is casted with the motor housing. Therefore, in order to change the MTB orientation we have to rotate the complete stator.
My question: What are the critical matters that must be taken care while doing so.

RE: Induction motor stator orientation

Mechanical issues.
Are the end bells interchangeable?
Will the rotor still be centered in the stator after the switch?
Usually the answers are yes.

Ohm's law
Not just a good idea;
It's the LAW!

RE: Induction motor stator orientation

I agree with Bill, it's just mechanical. You would flip the stator frame end-for-end but put the endbells back in their original positions (now flipped with respect to the stator).

In theory you could change the airgap during such evolution if there were offset bores on both the stator and endbell at one end that compensated for each other in the original configuration. And unfortunately it's very difficult to check airgap in small motors (maybe with odp you have a bit of access but none with TEFC). It's also remotely possible that original lack of perpendicularity between shaft axis and endbell flange on the stator could have been compensated for by opposite lack of perpendicularity between endbell flange and bearing seat on the endbell... that's quite a stretch but could induce a rotor bow and 1x vibration (btw any change in shaft extension position with respect to mounting holes will become irrelevant once the machine is aligned to the driven equipment). I guess in theory there's nothing that requires the OEM to set it up so that axial positioning would be unchanged during such swap, but it seems like every OEM builds their motors symmetrically so this can be done without any effect on axial position of shaft extension.

With all that said, I can remember about 5 times we have swapped endbells to correct terminal box location at our plant for small NEMA frame motors, and we have never encountered any problem with interchangeability of the endbells, or axial positioning, difficulty of alignment, or unusual vibration afterwards.

Also of course if rotation was correct in original orientation then a lead swap is required for new orientation. There may be auxiliary junction boxes for space heater or rtd to think about. Since it's a congested area make sure any air ports (side or end for odp, end for TEFC) are not blocked by whatever is next to the motor.

(2B)+(2B)' ?

RE: Induction motor stator orientation

Dear Mr. Tanweer Ahmed
T. " .... , in order to change the MTB orientation we have to rotate the complete stator...."
C1. The " best?" way is to {rotate} the [stator as a complete motor]. Refrain from removing the end covers as far as possible. Mechanical foot-mounting dimensions would likely to be different but the (shaft height) [remains the same].
C2. You may need to change the direction of rotation:
a) if it is DOL starting, irrespective of whether it is in Star or Delta; reversal any of the two incoming phases would change the rotation.
b) if it is Star-delta starting, consult the Electrical PE to look into the recent development on Star-delta connection. The century-old method of reversal of two incoming phases is NOT? the best/correct way. Look into the recent contactor manufactures' publications. For ( CW or CCW rotation ) , the connection/wiring is different!.
It is NOT simply by reversing any of the two incoming phases!
. Be aware.
Che Kuan Yau (Singapore)

Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.

Reply To This Thread

Posting in the Eng-Tips forums is a member-only feature.

Click Here to join Eng-Tips and talk with other members! Already a Member? Login


Low-Volume Rapid Injection Molding With 3D Printed Molds
Learn methods and guidelines for using stereolithography (SLA) 3D printed molds in the injection molding process to lower costs and lead time. Discover how this hybrid manufacturing process enables on-demand mold fabrication to quickly produce small batches of thermoplastic parts. Download Now
Design for Additive Manufacturing (DfAM)
Examine how the principles of DfAM upend many of the long-standing rules around manufacturability - allowing engineers and designers to place a part’s function at the center of their design considerations. Download Now
Taking Control of Engineering Documents
This ebook covers tips for creating and managing workflows, security best practices and protection of intellectual property, Cloud vs. on-premise software solutions, CAD file management, compliance, and more. Download Now

Close Box

Join Eng-Tips® Today!

Join your peers on the Internet's largest technical engineering professional community.
It's easy to join and it's free.

Here's Why Members Love Eng-Tips Forums:

Register now while it's still free!

Already a member? Close this window and log in.

Join Us             Close