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11 comments
Participant

Join Date: Aug 2008
Location: California at 153rd & Dropoff
Posts: 2

Reversing rotation of AC motor

08/31/2008 7:56 PM

How do I reverse the rotation of a 110V AC induction motor. I inherited this motor, approx 1 hp, that has no name/spec plate. It has what appears to be two capacitors, one larger than the other. It has six leads with numbered labels. Three leads are wired to the load (black) line and three wired to the common (white) line. It is being used on a 6x48 belt sander but runs in the wrong direction. Is there a cimbination of leads that will reverse the rotation?

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Pathfinder Tags: AC motor Reverse rotation
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Guru
New Zealand - Member - Interested in everything- see my Profile please APIX Pilot Plant Design Project - Member - Member Engineering Fields - Electrical Engineering - Member Engineering Fields - Power Engineering - Member Engineering Fields - Civil Engineering - Member Hobbies - Musician - Autoharp and Harmonica Hobbies - Hunting - Member Hobbies - Fishing - Member

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Location: Christchurch, (The Garden City), South Island, New Zealand
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Good Answers: 226
#1

Re: Reversing rotation of AC motor

08/31/2008 9:37 PM

Hello redneckinjunear

If you are able to properly measure the various windings with an Ohm-meter, the lowest resistance winding is normally the "Run" winding, with thicker diameter wire in that "Run" winding.

Reverse the end connections of that "Run" winding, connect up, and it should reverse.

If you are unsure of what I'm talking about, contact a local electrician, who should be able to reverse your motor within 10 minutes on-site.

Advise your progress here, with

Kind Regards....

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Anonymous Poster
#2

Re: Reversing rotation of AC motor

09/02/2008 12:25 AM

Hi,

the single pahse Induction motopr will be having two winding. One Starting (Main) & one Running (Auxiliry) Winding. It is just revising the direction of connection of Running Winding.

Regards,

N.Suresh

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3
Anonymous Poster
#3

Re: Reversing rotation of AC motor

09/02/2008 6:40 AM

If the wires are numbered 1,2,3,4,5,8 the 115volt conn. is 1,3,8 toL1 and 2,4,5 to L2.

reverse 5 and 8 if rotation is wrong.

666

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Participant

Join Date: Oct 2011
Posts: 1
#11
In reply to #3

Re: Reversing rotation of AC motor

10/06/2011 7:00 PM

This was extremely useful and it WORKED!! Thank you so much.

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Active Contributor

Join Date: Aug 2008
Posts: 10
#4

Re: Reversing rotation of AC motor

09/02/2008 8:59 AM

You cannot change rotation on some motors. If the label is still on the motor look to see if it says non reversible. If there is no label see post 3. Good luck!

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Associate

Join Date: Jan 2007
Location: Los Angeles, California
Posts: 35
Good Answers: 3
#5

Re: Reversing rotation of AC motor

09/02/2008 10:26 AM

If the motor has three terminals you probably cannot change the rotation electrically. However, you can often swap the motor end bells mechanically and reverse the rotation that way.

If the motor has four terminals, then two of them might be for each end of the start winding. You can revers rotation by swapping those two. Good Luck!

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2
Power-User

Join Date: Mar 2006
Location: Valdosta, GA
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#6

Re: Reversing rotation of AC motor

09/02/2008 6:30 PM

The following diagram was found at this link: http://www.metalwebnews.com/howto/elec-mtr/elec-mtr.html

This diagram illustrates that the only change to be made is the swapping of 5 and 8 as is explained in post #3 by Guest. This either places the capacitor on the 1 - 4 side or the 2 - 3 side. The capacitor placement in the circuit determines the rotation.

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Participant

Join Date: Aug 2008
Location: California at 153rd & Dropoff
Posts: 2
#7
In reply to #6

Re: Reversing rotation of AC motor

09/02/2008 8:29 PM

Thanks Keywalker,

You are the only one who got it right. I found the same info yesterday and made the swap. Motor now runs in proper directions.

Thanks everyone for the help>

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Power-User

Join Date: Mar 2006
Location: Valdosta, GA
Posts: 361
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#8
In reply to #7

Re: Reversing rotation of AC motor

09/02/2008 8:56 PM

My pleasure.

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2
Anonymous Poster
#9

Re: Reversing rotation of AC motor

09/03/2008 9:27 AM

A point of clarity:

A single phase inductive motor can be reversed simply by changing the RELATIONSHIP of run winding to start Winding.Either can be reversed,referenced to the other, to change rotation.A single phase motor with an open start winding can be hand started in either direction,but until initial motion is applied, it simply sits there and hums, soon to overheat or trip a breaker.There is a centrifugal switch in the endbell assembly that disconnects the start winding when the motor reaches a certain speed.It stays disconnected until the motor almost stops,then closes again.You can sometimes hear this "click" when a motor stops, just before it completely comes to a stop.The capacitor(s) are connected in parallel with the start winding, to give an extra "kick" to get things started under heavy starting loads.This is not the same as a run capacitor,on a split phase motor (PSC: Permanent Split Capacitor) , such as condenser fans on air condition systems.They use the capacitors to get a phase shift to start and run the motors,have no start contacts, and are usually very efficient.

3 phase motors are much simpler: no start contacts or capacitors, simply reverse any 2 phases to reverse rotation.

Drill and brush-type motors depend on the relative orientation of the field vesus the armature windings.

Permanent magnet motors have only 2 wires, such as toy motors.Simply reverse polarity on the two wires will reverse rotation.PM motors were once only used in toys, but now are commonly used in industry for certain applications.

HTRN

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Guru
New Zealand - Member - Interested in everything- see my Profile please APIX Pilot Plant Design Project - Member - Member Engineering Fields - Electrical Engineering - Member Engineering Fields - Power Engineering - Member Engineering Fields - Civil Engineering - Member Hobbies - Musician - Autoharp and Harmonica Hobbies - Hunting - Member Hobbies - Fishing - Member

Join Date: Nov 2007
Location: Christchurch, (The Garden City), South Island, New Zealand
Posts: 4484
Good Answers: 226
#10
In reply to #9

Re: Reversing rotation of AC motor

09/03/2008 5:46 PM

Hello "Guest",

from me

Kind Regards....

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Anonymous Poster (3); Gadget Guy (1); Jayt01 (1); jpenrose (1); Keywalker (2); redneckinjunear (1); Sparkstation (2)

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