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Repulsion elecric motor

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Graham Williams 504/12/2011 17:37:44
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Have got a motor off what I think is an ML4, the internal wires to the terminal plate are disconnected as are any power input wires ( except earth). The plate has 3 terminals marked A,T and N(orZ). Has anyone any idea how it should be connected please ?
Graham Williams 504/12/2011 18:28:03
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Decided, despite being told it was a repulsion motor that it is not. Have now taken the motor apart, despite knowing nothing about them !, and there is an inertial? mechanism there. There are 4 wires from inside the windings but only the 3 terminals on the plate. Closer inspection seems to show one terminal not marked and the others marked AZ and A. The T marking doesn't seem to have any connection 2 it. As before can anyone help in how to connect it?
Stub Mandrel04/12/2011 21:45:08
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That seems to be how the terminals on my Hoover single phase motor are marked. Live neutral and capacitor. I'll have look tomorrow, too tired now... been working all day
 
Neil
Ian P05/12/2011 08:03:08
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I think it would help if you could post a picture of the motor, or at least give all the details shown on the rating plate.
 
Ian
Graham Williams 505/12/2011 11:14:36
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Hi Ian.
Plate reads Crompton Parkinson
No.WTS524WA1B
0.25HP
230/250V
2.25 Amp
1PH
50Hz
Cont rating
Wire colours are Yellow/Green/Black/Brown (maybe originally Red)
Continuity between Brown? and Black nowhere else, don't have a meter so checked with battery/bulb.
 
Graham W
Ian P05/12/2011 11:39:12
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It sounds like a normal single phase induction motor.
 
If your yellow/green description refer to a single wire (so that there are three wires in total coming from the motor) then that is the earth lead and should be connected to the motor metalwork. The other two wires just go to live and neutral.
 
On thing you can do if you are unsure about things is wire a 100Watt (or 150W is better) in series with one of the wires to the mains. The motor may just run at low power (you might need to give the spindle a twist) but if the winding are shorted then the lamp will just light at full brilliance and no damage will be done. Once you know its OK wire up as normal.
 
Ian
Graham Williams 505/12/2011 13:03:33
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98 forum posts
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Hi Ian
All the wire colours are separate, i.e the green wire is a separate wire as is the yellow one, the yellow wire might be white though.
 
Graham W
Les Jones 105/12/2011 14:57:41
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Hi Graham,
In you second post you say there are only three terminals but then go onto say
one is not labelled
one is labelled AZ
one is labelled A
You then say "The T marking doesn't seem to have any connection 2 it." (I assume "2" mean "to")
Is T a fourth terminal or a wire coming out from inside the motor that dose not go to a terminal ?
 
If there are four wires and only three terminals does one terminal have two wires connected to it ?
 
The "internal mechanism" is probably a centrifugal switch which disconnects the start winding when the motor is up to speed. Does one of the wires from the windings go via this switch before coming out to the terminal box ? There should be continuity between the two connections on this switch when the motor is stopped.
 
Green used to be use as the colour for earth wires. Check to see if this wire connects to the metalwork.  If it does then you will have Identified one wire.
 
Les.

Edited By Les Jones 1 on 05/12/2011 15:00:46

Graham Williams 505/12/2011 15:53:42
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98 forum posts
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Hi Les.
 
There are only 3 post terminals 1 marked A , 1 marked AZ, the other has no letter but connects to a y shaped metal piece that makes and breaks on a set of points presumably when the centrifugal switch thing operates. The other markings on the paxolin terminal plate are against square holes but no post terminals.
Have just re-attached the terminal plate inside the end cover as at some point in it's life it had been attached with self-tappers and was flapping about which didn't look right even to me. In my ML7 book the A and AZ terminals look to be wired to live and neutral so going to attempt to follow that diagram with great care.
Stub Mandrel06/12/2011 21:15:59
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4318 forum posts
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1 articles
 
I don't know if this will help, but I just checked a single-phase capacitor start motor, Hoover possibly about 1950.
 
Six terminal points on a paxolin sheet behind a cover but only 2,3 and 4 are present (I assume the others would be used if it was 3-phase).
 
2 green cable to intyernal connection and cable to capacitor
 
3 Neutral connection and Capacitor
 
4 red cable to internal connection and Live.
 
I expect that 3 and 4 are connected to the 'run' coils on the other side of the paxolin.
 
I think the red and green go to the start winding, one of these via the centrifugal switch.
 
The earth connection is an external terminal - which means I have to run the 3-core into the motor and bring the earth wire back out the same hole!
 
Neil
 
Graham Williams 507/12/2011 08:37:38
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98 forum posts
9 photos
Hi all.
 
Got the motor running last night. I had an ML7 manual and extrapolated the wiring diagram and terminal naming ( i.e. A and AZ to U1 and U2) in that. So, as there was continuity on Brown and Black took that as the run wirings connected them to A and AZ, then connected the yellow (white?) to the unmarked terminal which worked thru the points mechanism and the other to A (U1) as I took that as the start wirings. Connected power in to A (live) and AZ(neutral) and Lo and behold the motor ran OK. Probably making everyone shudder with how I've done it knowing next to nothing about it but needs must. Thanks everyone for your input.
Ian S C07/12/2011 14:00:01
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7468 forum posts
230 photos
A repulsion motor has a wound armature, and a comutator and brushes, the brushes are short circiuted, in some case the brushes are lifted and some other mechanisim used to short the armature, at speed it runs as an induction motor. I seem to remember seeing one with the brush possition adjustable while running to alter the motor speed. Don't think you'll buy a new one today, but you could come across one on old machinery. Some of them got around the problem of shorting the armature buy putting bars as in a squirel cage induction motor so that all that is needed is a centrifugal lifting device for the brushes. You don't really want one, unless you are like a late friend who collected old motors for his museum.
Ian S C

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