Name that AC motor

Discussion in 'General Electronics Chat' started by jeffbos, May 27, 2012.

  1. jeffbos

    Thread Starter New Member

    May 27, 2012
    2
    0
    All,

    I picked up this AC motor at a flea market to use to run a blower in my shop. It has a 5/8" shaft. The motor runs fine and spins in CCW as viewed from the rear. It has 4 poles and a 120V capacitor. The man I bought it from said it was 120/220V.

    I attached two pics. One shows how the motor was wired when I got it. The other shows just the connectors in the motor.

    I'm used to modern day motors that have several labeled wires in them. This has three blades and a grounding screw. I was guessing two poles were for hots (use one for 120V and two for 220V) and one for the neutral.

    Does anyone know what I have here? Do I have it wired correctly? Is there a way to make it rotate CW?

    Thanks
     
  2. BSomer

    Member

    Dec 28, 2011
    433
    106
    I'm guessing that the "nameplate" on the motor is gone. It would have had the manufacturers name, model #, voltage rating, and such information.

    You said there is a capacitor, where is it wired in the motor?

    There may be a way to change the direction of rotation, but I am uncertain how this may be done without knowing the motor model and such. Others here may know how to wire it properly, I have generally had more experience with 3 phase motors.
     
  3. jeffbos

    Thread Starter New Member

    May 27, 2012
    2
    0
    All identifying indications are missing. I tried to check resistance with the capacitor but was getting inconsistent readings. It appears to be operating fine and it's spinning the way I need it to but I'd like to understand the wiring connections. I guess I could take it apart and check the wiring.

    Also, I wanted to calculate the HP of the motor. I was trying to get an amp draw by hooking my meter up to the positive and neutral connections on the motor while it was running. Got very little readings. Is there another way to check the amp draw? By it's size and 5/8" shaft, I'd like to think it was in the 1/2 to 1 hp range.

    Thanks
     
  4. BSomer

    Member

    Dec 28, 2011
    433
    106
    You can check the current draw with a clamp on amp meter. Just judging by the shaft dimensions isn't going to give an accurate HP rating. It can give you an idea. I'd say by the pictures it isn't going to be over 1 HP.
     
  5. strantor

    AAC Fanatic!

    Oct 3, 2010
    4,302
    1,988
    were you runnin it unloaded? if so, you're only going to draw meaningful amps when fully loaded.
     
  6. crutschow

    Expert

    Mar 14, 2008
    12,986
    3,226
    At full load a small induction motor has a slip of about 4% so to test the full load current you can mechanically load the motor until the speed drops 4% below the synchronous speed. For example this is about 1725 RPM for a 4-pole motor running from 60Hz.

    Another way to estimate its power is to look for AC motors with a similar physical size. The HP values should be similar to what you have.
     
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