220 1 phase motor issues
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    Default 220 1 phase motor issues

    My lathe motor starts but runs slow and gets very hot. It appears it is running on the start windings. I pulled the end off the motor and the wiring looks good as does the start switch. All wiring to the reverse SW is correct.
    Any suggestions?
    Thanks,
    Fred V

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    Maybe the start capacitor is weak and it is not getting fast enough to switch to the primary? Centrifugal mechanism stuck and not switching? Primary circuit open?
    A couple of troubleshooting ideas.

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    Is it easy to unload the motor? Maybe take off a belt then see if it is still a problem.
    Bill D
    Last edited by Bill D; 05-23-2021 at 12:26 PM.

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    Have a look at the start capacitor. Is it bulging anywhere? Appear dark? If so, I would suggest replacing it.

    If it were my problem, I'd replace the start cap anyway and see if things improve.

    Unloading the motor is a good idea, I agree with the above poster.

    metalmagpie

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    Quote Originally Posted by metalmagpie View Post
    Have a look at the start capacitor. Is it bulging anywhere? Appear dark? If so, I would suggest replacing it.

    If it were my problem, I'd replace the start cap anyway and see if things improve.

    Unloading the motor is a good idea, I agree with the above poster.

    metalmagpie
    I did not look at the start CAP thinking that if it starts turning it must be OK. I tested the run CAP with my VOM on CAP setting and it checked out OK. I'll look at the start CAP and report back.
    Fred V

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    If the motor does not reach full speed, replace the start cap. I wouldn't even mess with a VOM - the concern with electrolytic start caps is equivalent series resistance which a meter might not pick up on, not so much their actual capacitance reading. An electrolytic can read correct capacitance and still be bad. If they get breached, the electrolyte inside of them evaporates and they dry out & die. They're cheap enough to replace diagnostically. Wouldn't hurt to do the run cap while you're at it for peace of mind.

    Expendable jelly-bean parts.

    Motor Start Capacitors | Capacitors | Electrical | www.surpluscenter.com

    If it does reach full speed, inspect the centrifugal switch for proper operation. Failing that, check the lathe's countershaft and spindle bearings for drag.

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    Check the switch that takes the start cap out of circuit and investigate that run cap further. First thing I would do is check the motor's running amperage and see if it matches the nameplate. If the dropout switch is functioning and the running amps are high your run cap probably needs to be replaced. I had this problem on my Ingersoll air compressor once it got to be about 15 years old. Kept popping the thermal overload. Checked running amps and it was way over nameplate. Replaced the run cap and all was good again, been working great again for years now.

    And Sparky is bang on, your voltmeter cannot check ESR, the increase of which is what causes trouble in a capacitor. You need a special meter for that, called an LCR meter.

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    Another thing you might want to check for a run capacitor. Being the Run Cap. adds to the Start Cap. the amount of capacitance will be lowered if Run cap is bad. You may see only one capacitor but I had a motor where a Run Cap. was hidden in the motor base. Also possible is dual capacitor, check number of wires connected to the Cap.
    Best to unload the motor, if it is running on the start windings only it may shut down when speed activates the stitch or may start hunting, a grumbling sound because the capacitor is too large for the motor at the run amperage. Maybe disconnect the capacitor and power up for short time to see if the run winding is connected, it will hum and not start. Check to see if there is an overload thermal switch, usually single phase motors have them, it might be bad and disconnecting the run winding, I have seen them wired wrong so as to only disconnect the run winding.
    Problem with name plate amperage is that the amperage listed is if motor is under a load equal to the HP rating.

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    Bottom line just start by ordering a set of capacitors for it. You can probably get both for $4-7 before tax and shipping. That's a small price to pay for the amount of confusion a set of known good capacitors will preclude for you.

    If they fix the issue then you'll have saved a bunch of time rebuilding, inspecting and troubleshooting. If not, then you'll have ruled out two possibilities which can be tricky to positively isolate otherwise and will be able to move forward with confidence.

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    Quote Originally Posted by Fred V View Post
    I did not look at the start CAP thinking that if it starts turning it must be OK. I tested the run CAP with my VOM on CAP setting and it checked out OK. I'll look at the start CAP and report back.
    Fred V
    Thanks so much for the replies. I am embarrassed to admit this but I had wired the motor for high voltage thinking it was 120/240. I removed the motor and got to see the label and it is a 240/460!! so should be wired for low voltage. It now runs.

    Now for the next problem, see attached wiring diagram. How can this be wired to a 6 pole drum reversing switch? There are 5 wires that have to be dealt with. I don't see how to switch the L1 to T5 and be able to swap 6 to 8 to reverse.wiring.jpg

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    Letting us know that you had never actually had it running and had changed the wiring yourself would have been pretty pertinent information...

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    Quote Originally Posted by eKretz View Post
    Letting us know that you had never actually had it running and had changed the wiring yourself would have been pretty pertinent information...
    I did have it running, for several years. One day it just hummed but ran if I pulled the chuck. The wiring was funkey so I rewired it not remembering it was a 220/460 motor. I couldn't see the name plate with the motor installed so I wired it for high voltage.

    It runs perfectly now but i am concerned that it has to be wired with T1,3 always hot. The drum switch needs another set of contacts or a relay or breaker to turn the power on/off. I hope that makes sense. I'm not a newbie, I've wired my whole house and shop. I just haven't worked with motors a whole lot.

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    Quote Originally Posted by Fred V View Post
    I did have it running, for several years. One day it just hummed but ran if I pulled the chuck. The wiring was funkey so I rewired it not remembering it was a 220/460 motor. I couldn't see the name plate with the motor installed so I wired it for high voltage.

    It runs perfectly now but i am concerned that it has to be wired with T1,3 always hot. The drum switch needs another set of contacts or a relay or breaker to turn the power on/off. I hope that makes sense. I'm not a newbie, I've wired my whole house and shop. I just haven't worked with motors a whole lot.
    That bolded quote bit would generally indicate a failed start cap or winding or disconnected wire to one or the other of those.

    According to your diagram, for reversing; to run one direction 8 has to be connected to line 2 with 1 & 3. Then 6 should be joined to the 2,4,7,9 group. For the other direction reverse those connections. And your switch should allow you to break both live connections, if yours doesn't, might could get one that does.

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    Quote Originally Posted by eKretz View Post
    That bolded quote bit would generally indicate a failed start cap or winding or disconnected wire to one or the other of those.

    According to your diagram, for reversing; to run one direction 8 has to be connected to line 2 with 1 & 3. Then 6 should be joined to the 2,4,7,9 group. For the other direction reverse those connections. And your switch should allow you to break both live connections, if yours doesn't, might could get one that does.
    I have fixed it by adding start/stop button to the 220 supply line.
    screen-shot-2021-05-28-7.39.45-am.jpg


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