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Thread: Who are the Electricians amongst us?

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    Gold Member Dave S's Avatar
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    Who are the Electricians amongst us?

    Hi Guys, got a problem, please help.

    I acquired an old compressor that has "done it's time" however, someone has cocked up the motor wiring. It's a Cima type 90/2, 2 pole, 220V single phase induction motor. I've checked the coils (ohmmeter) and they are fine, no grounding, etc. Here's what I have.

    There are 4 wires coming out of the stator, 2-Red and 2-White (all disconnected). The starting Capacitor is disconnected but appears to be fine (charges and holds voltage), the connector block (6 connectors, marked U, V, W, U2, V2, W2) has cracked into 2-pieces and is disconnected. The incoming supply is also disconnected.

    Does anyone have a clue as to how to put this back together?

    PS I have replaced the bearings on the Rotor and checked the alignment of Rotor/Stator, all is fine. This compressor would probably still work if someone hadn't started poking around with the wiring, all it needed was bearings, old ones were seized.
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    It is more than likely a capacitor start single phase motor with a centrifugal switch.

    The centrifugal switch should be in the closed position so you can check the resistance, to see which winding has the higher resistance which should be the start winding if I remember correctly, long time since I played with a single phase motor.

    just to simplify it a little label the wires with a number

    run - white 1 ( lower resistance)
    run - white 2 (lower resistance)
    start - red 1 (higher resistance)
    start - red 2 (higher resistance)
    cap - black 1
    cap black - 2


    then you connect if using cabtyre,

    L = red 1 - white 1 (brown)
    N = white 2 - black 2 (blue)
    X = red 2 - black 1 (a spare terminal with no other wires connected)
    earth to the frame with a lug (yellow and green)


  3. #3
    Gold Member Dave S's Avatar
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    Hi Ian, I'm getting the following:

    1&2. Red wire (1.5 Ohm) Run?
    3&4. White wire (2.5 Ohm) Start?
    5&6. Both White Cap. (60 uF Non-polarised)?
    No Centrifugal switch

    Correct me if I'm wrong, the Cap. goes in series with the start winding (dictates start direction)? Then the connections are simply "L" to Cap. and Run winding, other Cap. lead to Start winding? "N" to other end of both windings? And "E" to motor ground?
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    I refer to,

    L1 as live
    L2 to neutral

    L = brown wire from cabtyre, join to run coil wire and start coil wire
    N = blue wire from cabtyre, join other run coil wire and to one cap wire
    X = being just a connection, cap wire to join to other start coil wire

    you will only see the centrifugal switch if you open the back of the motor, it will be connected internally.

    If it runs in the wrong direction just swop the start coil wires.

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    I would normally just stop at my local armature winder and they do it for me, perks of having big motors rewound

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    Dave S (07-Jun-13)

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    Gold Member Dave S's Avatar
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    Thanks Ian, I got it sorted, runs like a charm, and in the right direction too.
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