Results 1 to 8 of 8
  1. #1
    Screwmachine is offline Stainless
    Join Date
    Mar 2001
    Location
    Switzerland
    Posts
    1,867

    Default Start capacitor, how to wire?

    Oddly enough I've never had to do this. I just got a little motor for a project and it has no capacitor; stumped me for a moment why it would only run when I spun it up

    Data plate info:
    220v .25A 50hz 1250rpm with 4uF listed. I can dredge up a cap, just need to know where to put what wire.

    Wires:

    1 blue
    1 brown
    1 black

    the black is the same gage but with much thinner insulation. I hooked the blue and brown (usual hot and neutral colors here) to 220v and she ran when spun.

    No way to see what the wires do in the motor as they disappear into the windings.

  2. #2
    jonfritch is offline Aluminum
    Join Date
    Jul 2006
    Location
    Little Rock Arkansas US of A
    Posts
    98

    Default Where?

    The start cap goes in series with the start winding. If your motor as a start switch on the rotor with a pair of contacts that are closed when the motor is at rest, take 1 of those wires off the contact and put it on the cap, then wire the other side of the cap back to that contact.

  3. #3
    avivz's Avatar
    avivz is offline Aluminum
    Join Date
    Jan 2009
    Location
    Israel
    Posts
    97

    Default

    I'm not sure what you see is a starting capacitor but a phase shifting capacitor, which is common on single phase induction motors. Sometimes called "Run capacitor". This capacitor provide the auxiliary winding a 90 deg. shifted current. Look here: http://www.allaboutcircuits.com/vol_2/chpt_13/9.html for the "Permanent-split capacitor motor"

    Use ohm-meter to messure the resistance between all the wires and note it here.

  4. #4
    Screwmachine is offline Stainless
    Join Date
    Mar 2001
    Location
    Switzerland
    Posts
    1,867

    Default

    Quote Originally Posted by avivz View Post
    I'm not sure what you see is a starting capacitor but a phase shifting capacitor, which is common on single phase induction motors. Sometimes called "Run capacitor". This capacitor provide the auxiliary winding a 90 deg. shifted current. Look here: http://www.allaboutcircuits.com/vol_2/chpt_13/9.html for the "Permanent-split capacitor motor"

    Use ohm-meter to messure the resistance between all the wires and note it here.

    Between the blue and brown I'm getting .336Kohm, between blue/black and brown/black it's .334Kohm.

    Here's a pic of the motor (if that helps any ).




  5. #5
    JST's Avatar
    JST
    JST is offline Diamond
    Join Date
    Jun 2001
    Location
    St Louis
    Posts
    12,089

    Default

    Well, its EUROPEAN...... that explains the colors totally...... so the black wire is the capacitor.

    use your ohmmeter.

    Find the wire to which the black has the lowest resistance..... that is the common, and the cap should go from black to the other one.

  6. #6
    rons is offline Stainless
    Join Date
    Mar 2009
    Location
    San Jose, CA. USA
    Posts
    1,398

    Default

    Don't be mis-lead by the terminology. Start capacitors are used to phase shift
    the current in relation to the voltage for a brief period of time to get the rotor
    inside the motor to turn. Then it is switched out. If you can substitute a oil
    filled capacitor for you motor you will probably never have to worry about the
    capacitor wearing out again.

  7. #7
    SAG 180's Avatar
    SAG 180 is offline Titanium
    Join Date
    Sep 2007
    Location
    Cairns, Qld, Australia
    Posts
    2,038

    Default

    That looks like a cap run motor as Avivz suggests: I can't see the centrifugal switch on it, so the common black wire goes to neutral and the brown wire to active leaving the blue to go to one side of the run cap with the other side of the cap going to active/brown. Run it for a very short time and watch for smoke with one hand on the power switch. A single phase motor should draw close to full rated current with no load if you have a clamp meter to check the black wire.

  8. #8
    avivz's Avatar
    avivz is offline Aluminum
    Join Date
    Jan 2009
    Location
    Israel
    Posts
    97

    Default

    It seems a bit strange to me that the resistance between all the leads is pretty much the same. Anyway I suggest that you contact these folks: http://www.groschopp.de/index.php?jump=en and ask, just to be sure. It will be a waste do damage it while you cannot trust the color of the wires.

    Aviv.

Bookmarks

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •