Help ascertaining motor connections

Discussion in 'General Electronics Chat' started by Andrew Leigh, Sep 29, 2013.

  1. Andrew Leigh

    Thread Starter Well-Known Member

    Sep 8, 2008
    92
    2
    Morning,

    I have a fraction hp motor with intergral gearbox that I would like to use for a project.

    The motor rating plate is:

    Frame: P335
    Winding: PC (could that be permanent capacitor?)
    Voltage: 230
    Torque: 5lb in
    Speed: 100rpm

    There is no power output but based on the size it can't be more that 150W?

    There are four wires coming from the motor housing. Two black wires and two brown. A black and brown have been connected to a terminal block and appear to be Live and Neutral. The other Black and Brown wire have been bridged out and there is a 1.5uF 440V Capacitor on the side of the motor that is not connected as the leads have broken off flush with the resin filling.

    When 230V is applied to the "live and neutral" the motor just hums.

    Two questions are then;

    Is it reasonable to assume that the bridged black and brown are in fact the connections for the capacitor.

    Is is reasonable to assume that the 1.5uF capacitor is correctly sized for the motor. The motor is old but the cap is of much newer vintage.

    Thanks
     
  2. MaxHeadRoom

    Expert

    Jul 18, 2013
    10,553
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    A few possibilities on that small a motor, two speed etc?
    The motor will just hum without the start/run winding connected.
    Measure the resistance between windings, if they all have continuity with each other and the same resistance, the windings could be equal in which case the run and cap start/run can often be interchanged, but it is pure speculation at this point.
    I see the cap at 1.5μf about right.
    Max.
     
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  3. killivolt

    Active Member

    Jan 10, 2010
    369
    317
    Is the capacitor Bi-polar or Polar? Its possible if both browns have no stripe your capacitor is bi-polar and both browns go to the cap. You'll find this on furnace motors today.

    But, you say you have a black and a brown not connected? Right.

    It's possible that it is polar connect them, connect them to the correct terminals, but you say they are bridged? Not sure what you mean by that, are they connected to the same terminal? Try measuring the voltage, if it's zero, their connected to the same terminal block, which is confusing. If not find the polarity neutral and hot. but get the part # on the cap and maybe you can find out what type often they mark them with a paint dot to indicate polarity.

    Good luck.

    Like max said, it's a crap shoot without knowing your resistances.

    Does it look like this? http://www.ebay.com/itm/EMERSON-Motor-P335-3-4Hp-3Ph-P63ZF-1364-1725rpm-/230613827488
     
    Last edited: Sep 29, 2013
  4. killivolt

    Active Member

    Jan 10, 2010
    369
    317
    I found this as an example, easier to read the diagram. Your colors are off but it's a start.

    Go to the bottom 2 motors, condenser fan Motors. 230v psc not PC. 370v polar caps. Find the wiring configuration.

    Ignore the second Diagram C/W and CCW, it's just for reversing the motor, those (wires) are not shown in the first diagram. Just look at the first diagram.

    http://www.acsuperstore.com/specs/wagner/LIT-T-MOTORS_spec.pdf
     
  5. Andrew Leigh

    Thread Starter Well-Known Member

    Sep 8, 2008
    92
    2
    Thanks,

    as a matter of interest I measured with a multimeter ans get the following wiring diagram. Will go through your posted link thanks.

    [​IMG]
     
  6. Andrew Leigh

    Thread Starter Well-Known Member

    Sep 8, 2008
    92
    2
    The Black / Brown open is actually where they had bridged the winding. I disconnected the bridge to measure the windings.

    The Black / Brown measuring 316R was obviously taken with the bridge connected.
     
  7. MaxHeadRoom

    Expert

    Jul 18, 2013
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    It would appear that both windings are identical, which it often is on small motors, so presumably you could put 120v across one winding, (Main) and put a capacitor in series with the other winding (Start/run) across the same supply.
    Max.
     
  8. Andrew Leigh

    Thread Starter Well-Known Member

    Sep 8, 2008
    92
    2
    Sounds about where I was going with this. Thanks guys appreciate the help.
     
  9. MaxHeadRoom

    Expert

    Jul 18, 2013
    10,553
    2,375
    If it works, to change direction swap any single pair.
    Max.
     
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  10. Andrew Leigh

    Thread Starter Well-Known Member

    Sep 8, 2008
    92
    2
    Ah excellent. Knowing my luck would have had it in the wrong direction :).
     
  11. killivolt

    Active Member

    Jan 10, 2010
    369
    317

    I thought the OP said it was a 230v motor? Motors in Europe will be wired and color coded differently than this one, I'm guessing it's old enough it didn't follow the normal colors e.g.

    If the rating plate on this motor says 230V and it has a brown wire (the 230V "hot" or live"), a blue wire (the "neutral") and a yellow/green wire (the "earth" or "ground") it was designed for use in Europe or other world areas which use a 50Hz supply.

    I'm confused how well it will run and if he should connecting it, 230v and Ground. It maybe to old? Doesn't follow the color code?

    I'm don't know what they have over there.
     
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  12. MaxHeadRoom

    Expert

    Jul 18, 2013
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    He mentions two black and two brown?
    Max.
     
  13. Andrew Leigh

    Thread Starter Well-Known Member

    Sep 8, 2008
    92
    2
    Yeah sorry chaps, indeed we are on the eastern side of the pond so blue and brown it should have been. However the motor was probably made around 1970 in the U.K, so black and brown seem to have been the "convention" at the time.

    Done a little reading and along with the advice here I am hoping that this connection schematic will provide me with ON/OFF as well as the option of reversing direction of rotation.

    Would it be clever to reverse rotation while the motor is powered? I would like a limit switch at the one end and to have the motor automatically reverse? The speed stated is 100rpm and as it has an integral gearbox, I would assume that this is the output speed then on the gearbox shaft? The motor is probably 1400rpm so at 14:1 the gearbox should stop almost immediately? The motor will be driving a threaded rod M20 with a 2mm pitch (circa 3/4" with a 5/64" pitch).

    I have included a schematic of how I believe the connections should be with a manual reverse switch. How could one simply and elegantly have limit at the one end allowing the threaded bar to immediately reverse rotation?

    Thanks

    [​IMG]
     
  14. Andrew Leigh

    Thread Starter Well-Known Member

    Sep 8, 2008
    92
    2
    Just another question if I may. Could not get a 1.5uF today but could get a 1.0 and a 2.0uf, which one would be better, bought both?
     
  15. MaxHeadRoom

    Expert

    Jul 18, 2013
    10,553
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    It is not wise to 'plug' a split phase motor and do instant reverse, it can and is done on 3 phase motors though.
    I would go with the 1.0μf, make sure you get AC Motor Run type.
    If the 1.5 was optimum, going slightly higher will increase the start winding current slightly.
    IF you find that starting is slow or hesitates or you intend starting under load, then use the 2.0μf.
    Make sure the motor has stopped before energizing reverse.
    Max.
     
    Andrew Leigh likes this.
  16. Andrew Leigh

    Thread Starter Well-Known Member

    Sep 8, 2008
    92
    2
    Thank you very much.
     
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