240v single phase ac motor

Discussion in 'The Projects Forum' started by yoamocuy, Jan 20, 2015.

  1. yoamocuy

    Thread Starter Active Member

    Oct 7, 2009
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    0
    Hello,

    I have a 240v single phase motor used in a table saw but dont have a wiring diagram for it. The motor has 4 cables - 2 blue, 1 black, and 1 brown. One of the blue cables and the black cable are tied together. The resistance between the blue and brown wire is 15 ohm. Between the blue/black and brown is 5 ohm. For the saw itself, there's a cord with a blue, brown, and green wire. The green is earth. There's also a large cap that i assume goes in series with 2 of the wires but i'm not sure which. Could anyone shed some light on how i could figure out the right way to hook this up?
     
  2. MaxHeadRoom

    Expert

    Jul 18, 2013
    10,548
    2,373
    Separate the blue/black and determine if you have two separate resistances of 15 and 5, a normal 1ph motor would have the 15 ohm connected across the supply L1 & L2, and one end of the 5 ohm would be connected to one of these, say L1, the other end of the 5 ohm would go to the cap and the other lead of the cap would go to L2.
    To reverse the motor, swap any L1 L2 pair.
    Max.
     
  3. MaxHeadRoom

    Expert

    Jul 18, 2013
    10,548
    2,373
    I noticed I goofed in the resistances, it is the 5 ohm that should be across L1 & L2 and vice versa for the 15 ohm (start winding).
    Max.
     
  4. yoamocuy

    Thread Starter Active Member

    Oct 7, 2009
    80
    0
    I seperated the blue and black. The black has 5ohm and the blue has infinite resistance. Could you clarify what is L1 and L2? I don't have any tranformers or inductors.
     
  5. MaxHeadRoom

    Expert

    Jul 18, 2013
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    L1/L2 is the 240vac conductor supply.
    Without the cap, you would normally see two coil values on the separated wires, the 5Ω and 15Ω .
    Max.
     
  6. yoamocuy

    Thread Starter Active Member

    Oct 7, 2009
    80
    0
    I'm sorry, i'm not completely following you. I understand the L1/L2 now, but the cap is currently disconnected and i still don't see resistance on the blue wire. Also, i only have one connection available for the 5 ohm so i cant connect it to both terminals of the conductor. Could you maybe attach a drawing? Sorry, as you cna tell, i have no expeeience with ac motors
     
  7. MaxHeadRoom

    Expert

    Jul 18, 2013
    10,548
    2,373
    Google Split Phase motor, and also here.
    http://www.usmotors.com/Connections/Connections.htm
    One (run) winding is connected directly across the supply, the other (start) winding is connected across the supply in series with a capacitor, you may have a normally closed centrifugal switch internally to disconnect the motor when up to speed.
    Max.
     
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