JohnN
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| posted on 21/6/06 at 09:24 PM |
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Wiring up a single phase motor (Lathe)
I recently disassembled my myford lathe pending reinstallation on a new cabinet.
I want to urgently turn some small parts.
The motor is sinle phase with 4 wires, can I just fit a plug and use it like this temporarily/
Which wires go to which plug terminals?
Any ideas (without prejudice!) 
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tegwin
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| posted on 21/6/06 at 09:30 PM |
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When you took it appart did you remove a capacitor?
To run a motor from an AC supply you must fit a "motor run capacitor"....this is why there are four wires...
The motor will effectivley be a tripple phase motor using (i imagine) two windings...[2 wires per winding]...
By using a capacitor you can alter the relative phase of the power supply to each winding to make the motor spin...
Will see if I can dig up a diagam for you..
Dunc
[Edited on 21/6/06 by tegwin]
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cossey
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| posted on 21/6/06 at 09:38 PM |
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the wires are the two windings they should be 2 pairs one pair should be either red/black or blue brown which is the main winding and the other two
determine the direction of rotation.
you need the blue and one of the other pair to the neutral and the brown and the other wire to the live, if the motor turns the wrong way swap the
second pair around.
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JohnN
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| posted on 21/6/06 at 11:06 PM |
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No capacitor - the motor is an old english electric with four wires red, blue, green & white.
My gut feeling says wire green & red to live and the blue & white to neutral - I'll give that a go.....
Stand back!
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David Jenkins
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| posted on 22/6/06 at 07:28 AM |
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Erm... get some advice before doing that!
Single-phase motors have 2 windings - a big fat starter winding and a smaller run winding. Usually there is some mechanism that switches in a large
capacitor with the start winding to knock the phase out a bit to get the motor running. Once the motor is up to speed a switch operates to disconnect
the start winding.
the scope for mayhem and smoke is quite impressive if you get it wrong... there could be a lot of amps involved.
Also, don't just stand the motor on the bench when you try it out - if by pure chance you manage to connect the motor properly the torque may
fling it off the bench!
Have a look in Yellow Pages to see if there's an electric motor rewinder in your town. I've been lucky and found friendly ones who were
prepared to help out. Mind you, due to their help and friendliness I've usually bought stuff from them in return (bearings, capacitors,
etc.).
There's also a decent book available in the model engineering press about salvaging, fixing and wiring electric motors - worth getting a copy
from Amazon. THIS ONE
So, don't fiddle with it - find out!
David
[Edited on 22/6/06 by David Jenkins]
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Bob C
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| posted on 22/6/06 at 09:58 AM |
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Does this motor have a commutator? - you might have a universal motor there rather than an inductuion motor - the comments above were all about
induction machines.
If you do have the commutator motor you can do variable speed by putting a lamp dimmer type circuit in the armature circuit (not the field circuit,
that would make it speed up....)
Bob
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Krismc
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| posted on 22/6/06 at 03:10 PM |
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quote:
posted on 21/6/06 at 11:06 PM
sumone go and check he is still alive!!!
Built, Ivaed, Drove and now Sold - 2011 MNR VORTX RT+ 2000cc Zetec on R1 Throttle boddies.
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David Jenkins
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| posted on 22/6/06 at 03:17 PM |
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...take some oxygen...
[Edited on 22/6/06 by David Jenkins]
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t.j.
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| posted on 22/6/06 at 04:55 PM |
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I think he owns a motor wiht three phases.
4 wires, old motor etc.
If the motor give light it's no good
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JohnN
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| posted on 22/6/06 at 07:54 PM |
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Well, thanks for the help & concern -
I'm still alive, and ......
Yes it runs, it even turns the right way.
I confess, that found a wiring diagram for a US Motor, motor, that seemed to say to link start and run windings in parallel, plus a bit of info I
found on terminals for english electric motors.
In the end it was a gamble, I stood well back and trusted to the main fuse switch...
Now then I also have another motor, this only seems to have two available terminals, out of 5 numbered ones, oh and this motor has a big fat capacitor
attached - I'm guessing that I just wire up live and neutral to the two available terminals - there's only one way to find
out.................
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David Jenkins
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| posted on 23/6/06 at 07:45 AM |
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Death Wish II
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tks
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| posted on 23/6/06 at 08:15 AM |
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mhh
its easy if you know the amperage/wattage...
then just search for the ohm value calculated between the pins..
Regards,
Tks
The above comments are always meant to be from the above persons perspective.
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