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3 Phase 6 Wires

Discussion in 'Electrical Engineering' started by Bob La Londe, Jan 7, 2012.

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  1. Bob La Londe

    Bob La Londe Guest

    I have a Leland 6273 3 phase 240 V motor I am trying to figure out how to
    hook up.

    It has 6 black wires coming out of the motor.

    It also has 2 much smaller brown wires coming out that were just tied out of
    the way to the lifting ring. I suspect those were for a tach or possible a
    heat sensor.

    It just has paper labels on the black wires, and they look like they were
    put on by somebody who tried to figure out the motor in the past. They do
    not match up with any of the three phase wiring numbers/ letters standards
    I've been able to find. I want to hook it to a VFD for testing. Since the
    data plate says it will operate from 6-130 HZ and lists a range of RPM from
    96 to 3680 that tells me was probably intended to operate off of VFD in the
    first place.

    Is there any practical way using a meter to determine which wires to pair up
    to connect to 3 connections on the VFD?
     
  2. Bob La Londe

    Bob La Londe Guest


    The wires are in groups of 3. Any 2 in the first group read about 20 ohms.
    Any 2 in the second group read about 2 ohms.


    I read something about that already. Seems one guy use a small DC power
    supply like a battery and measures the direction of deflection on adjoining
    windings when he removes the power source. Sounded like it would be easy to
    get confused that way, but I may be reduced to that.

    The data plate reads:

    Leland Electrosystems Inc
    Model 6273
    Serial TX43042
    FR 215
    HP5
    HZ 3/130
    C Temp rise Cont.
    NO.71
    RPM 96-3680
    Class H insulation
     
  3. Baron

    Baron Guest

    Bob La Londe Inscribed thus:
    You might find that its dual voltage, 240/480 3Ph, and delta connected.
    In which case wire one lead of one set to each phase, if the motor runs
    the wrong way for you, just swap any pair. Check that there is no
    connection to the frame from any wire first. Put the other three wires
    into a piece of three way chocolate block to insulate them. Just to
    test I would start with the higher resistance winding which is probably
    for a 480volt feed.
     
  4. Bob La Londe

    Bob La Londe Guest


    Ok... I got it figured out. Mostly... Its got an independent fan motor.
    Doh! Had I been a bit more observant I would have seen that myself, but
    somebody in another group pointed out the possibility, and commented on the
    probability because a motor turning only 96 RPM at 3 Hz can't possibly be
    turning a fan fast enough to cool itself.

    It was easy enough to check. I spun the fan and held the brake disc on the
    motor with my other hand. Wheeeeeeee!!!

    It has six primary leads because there are two motors.

    I suspect the 2 smallish brown wires are a thermal sensor. Not sure I can
    test it except maybe... to wire up the motor and not the fan motor. LOL.
     
  5. Don Kelly

    Don Kelly Guest

    There is nothing said that indicates Y or delta connection and, for dual
    voltage, the 20/2 DC resistance level doesn't strike a bell.
    Even at 480V, a 20 ohm line to line DC resistance appears quite high for
    a 5HP motor. I suspect that the 2 ohm windings are the main windings.
    However, without the actual motor specifications, this is all conjecture.
     
  6. Baron

    Baron Guest

    Bob La Londe Inscribed thus:
    Very true. The same applies to the fan motor if it runs the wrong way.
    Just swap any pair of its wires.
    I had overlooked the possibility that there was a fan motor in there !
    Sorry. :-(

    But please use an insulation tester (megger) and make sure that there
    isn't any leakage to the frame from any wire group. If the motor has
    been stood for a while damp can cause any leakage current to be higher
    than normal. Just run the motor without the fan to get it warm enough
    to drive off the damp. I've seen VFD's damaged because of high leakage
    current to the earthed frame. Sometimes these motors come onto the
    market because of this and its cheaper to replace rather than repair
    it.

    Anyway I'm glad that you've cracked it.
     
  7. Baron

    Baron Guest

    Don Kelly Inscribed thus:
    I agree. I faulty assumption on my part ! I missed the vfd rating
    indicating that it would have a fan motor.
     
  8. Bob La Londe

    Bob La Londe Guest

    Well, its been sitting in my shop in SW Arizona for a year, so I suspect it
    has probably dried out quite a bit. I will check for impedance to ground
    before running the motor. Probably have to get a different VFD if I run the
    motor to full power. It was originally used for 3 in 3 out for speed
    control, but I do not have 3ph available, so the VFD will not be able to
    handle the motor if its loaded much beyond half capacity. (I do have (and
    have read) the manual for the VFD). I need to break down and get a second
    VFD for the fan motor anyway. Eventually I suppose I should just put a 10HP
    rotary phase converter in my shop.
    The stupid part is I pulled the back cover to check the fan since there was
    a dent in the cover. The fan motor is fully visible. Its just not what I
    expected to see so I didn't see it. I didn't even realize that the output
    shaft (still connected to the mechanical load) took more force to turn than
    the fan. DOH! LOL. Once I realized what I was looking at I couldn't
    believe I didn't see it to begin with.
     
  9. Baron

    Baron Guest

    Bob La Londe Inscribed thus:
    See Note below:
    I wish I had a $/£ for every time I've looked at something and simply
    not seen it.

    Note:
    You could test the fan motor on single phase by using a capacitor to
    feed the third wire. Try one from a fluorescent light fitting or
    anything similar like a washing machine motor. Small motors tend to be
    fairly intolerant of actual value.
     
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