Single Phase Cap start motor wiring

Discussion in 'General Electronics Chat' started by tetanus4, Oct 24, 2013.

  1. tetanus4

    Thread Starter New Member

    Oct 24, 2013
    4
    0
    I have a single phase, 220VAC 5hp motor that used to run but recently was moved and disconnected and lost name plate with the wiring diagram.There are six leads and I used an ohm meter to identify three coils, the starting coil attached to the three cylindrical caps. Can anyone tell me how to wire this together? I assume to reverse the direction I can swap the starting coil wires. Attached is a diagram of the configuration as found.

    Thanks in advance,
    Gary
     
  2. MaxHeadRoom

    Expert

    Jul 18, 2013
    10,564
    2,379
    Do you recall if this was originally a 2 SP or Dual voltage motor?
    Reason 3 windings?
    Max.
     
  3. tetanus4

    Thread Starter New Member

    Oct 24, 2013
    4
    0
    No, I don't think it was dual voltage. The three windings is what has me stumped; it's not typical.
     
  4. tinkerman

    Member

    Jul 22, 2012
    136
    34
    Usually these motors are dual voltage but this being 5 HP may be single voltage. It would draw too much current for 120 volt connection. Probably have to connect the two windings you have identified as 3-4 and 5-6 in series. However they must be connected with the correct polarity. Connect the start winding from what looks like 2-3 on your drawing to the center point of the main windings and to one of the outside legs. To reverse direction of rotation connect the start winding to the opposite outside leg. If it doesn't start it's likely that one of the mains is the wrong polarity. Reverse either main and try again. There should be a starting switch somewhere in that start circuit. The three items in the top of your drawing look like they are capacitors but no switch and they are not usually connected as shown. BTW, the number used here is not standard.
     
  5. nsaspook

    AAC Fanatic!

    Aug 27, 2009
    2,912
    2,176
    Maybe it's really a three phase motor that's been converted to single phase operation with a delta phase capacitor. I've seen them with several capacitors in parallel for start mode, with a switch to remove some for a run value.

    http://www.youtube.com/watch?v=43eAEeyTbs8
     
    #12 likes this.
  6. tinkerman

    Member

    Jul 22, 2012
    136
    34
    I forgot to mention there is an easy way to check if you have the main windings connected correctly. Connect them in series and power up with 120 volts. Give the shaft a spin. You could wrap a string around the shaft and pull to get it spinning. The motor won't have much torque and will be slow starting. If the windings are not correct it won't run so reverse either winding and try again. Once that has been determined add the start winding.
     
  7. tinkerman

    Member

    Jul 22, 2012
    136
    34

    I tend to think not since the resistances are not equal. What are the values of the capacitors? Is one a metal can? That would indicate a run cap.
     
  8. tetanus4

    Thread Starter New Member

    Oct 24, 2013
    4
    0
    All three caps are metal can, same size, but I can't read them without removing them.

    I noticed that I numbered the leads to include two labeled "3". I will just call the second "3" now "7". So get that I need to wire the two running coils in series (connect leads 4 & 5, but after that I am not clear on your terminology:

    "Connect the start winding from what looks like 2-3 on your drawing to the center point of the main windings and to one of the outside legs."

    Are you calling leads "7" and "6" the outside legs? Is the center point leads "4" and "5"? When you say connect the start windings 2-3, to the center point, are saying connect lead "2" or "3" to 4-5? What happens to lead "1"?

    Thanks for your help.
     
  9. tinkerman

    Member

    Jul 22, 2012
    136
    34
  10. tinkerman

    Member

    Jul 22, 2012
    136
    34
    Join 4-5. apply power to 3 and 6. Connect one end of the start winding, 3 to 4-5. Connect the remaining end (3) of the start winidng to either 3 or 6. If you conect to 3 it will rotate one direction, if you connect to 6 it will turn the opposite direction. (assuming 3-4 and 5-6 are the correct polarity. You may have to reverse 5-6).

    Odd the caps are all metal and the same size. I didn't expect that.
     
  11. tetanus4

    Thread Starter New Member

    Oct 24, 2013
    4
    0
    Thanks, I will give that a try and let you know the results
     
Loading...