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single phase motor no longer working reverse

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  • 19-12-2020 10:51pm
    #1
    Sparkey84
    Registered Users Posts: 293 ✭✭


    hiya guys ive been testing out a circuit today and would appreciate any knowledge someone might share. i have a motor going to a roller door which worked in both directions now it only works in one
    there are 4 wires coming out of the motor. live earth and two wires going to a capacitor

    the original wiring sends live to live when the door is to come up and live to one of the capacitor wires when the door is going down, depending on which position the switch is in.

    if its a case im looking at a new motor ill probably change to a simple manual chain pulley system. i dont really want to get someone in to tell me i need a new motor and reply by saying im not going to get one. on the other hand if it just needs a capacitor id fix it.

    if anybody happens to have a strong suspicion either way that might help decision id appreciate any input, thanks


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    #2
    Sparkey84
    Registered Users Posts: 293 ✭✭Sparkey84


    i should add if i manually raise the door the motor will bring it down (in both switch positions)really sweet no buzzing or motor problems


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    #3
    antoinolachtnai
    Registered Users Posts: 9,776 ✭✭✭antoinolachtnai


    Sparkey84 wrote: »
    i should add if i manually raise the door the motor will bring it down (in both switch positions)really sweet no buzzing or motor problems

    Does this help?

    https://youtu.be/__nS3OelY-s


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    #4
    Andrea B.
    Registered Users Posts: 1,921 ✭✭✭Andrea B.


    May be cap. Motor can go either direction without. Weight of door downwards might be initiating that direction.


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    #5
    Sparkey84
    Registered Users Posts: 293 ✭✭Sparkey84


    thanks guys yeah that video explains the circuit in use perfectly.

    for the downward motion the spring tension is high enough that the door nearly wants to come back up of its own accord. i move the pulley by hand and it requires less strength to lift the door than drop it.

    cap fail does make sense but to have it fail in only one rotation is the part that has me confused

    the cap is old there are no marking whatever on it. so considering a replacement will be hard, i found a chart online that suggests a 140micro farads cap based on the hp 1.25 but i also found an online calculator that said 30 md ????


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    #6
    aido79
    Moderators, Regional Abroad Moderators Posts: 5,374 Mod ✭✭✭✭aido79


    Sparkey84 wrote: »
    thanks guys yeah that video explains the circuit in use perfectly.

    for the downward motion the spring tension is high enough that the door nearly wants to come back up of its own accord. i move the pulley by hand and it requires less strength to lift the door than drop it.

    cap fail does make sense but to have it fail in only one rotation is the part that has me confused

    the cap is old there are no marking whatever on it. so considering a replacement will be hard, i found a chart online that suggests a 140micro farads cap based on the hp 1.25 but i also found an online calculator that said 30 md ????

    Are there relays to control which side of the capacitor the live is sent to?


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    #7
    Sparkey84
    Registered Users Posts: 293 ✭✭Sparkey84


    aido79 wrote: »
    Are there relays to control which side of the capacitor the live is sent to?

    hiya, yeah the selector switch sends power to one side or the other based on what is selected and then the selector switch receives power by a push to make, in fairness its a nice system as the door can only be powered while someone is there looking at it.

    after some more testing ive realised the cap must be bad as the two poles make a circuit when tested with a multimeter

    i intend on picking up a cap i the morning after night shift and going at it tomorrow.


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    #8
    aido79
    Moderators, Regional Abroad Moderators Posts: 5,374 Mod ✭✭✭✭aido79


    Sparkey84 wrote: »
    hiya, yeah the selector switch sends power to one side or the other based on what is selected and then the selector switch receives power by a push to make, in fairness its a nice system as the door can only be powered while someone is there looking at it.

    after some more testing ive realised the cap must be bad as the two poles make a circuit when tested with a multimeter

    i intend on picking up a cap i the morning after night shift and going at it tomorrow.

    Sounds like it's definitely the capacitor. Might be a good idea to give an update when it's fixed in case someone else has the same problem in the future.


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    #9
    Sparkey84
    Registered Users Posts: 293 ✭✭Sparkey84


    so long story short it was the cap, and working through the logic the only way the direction could have reversed on the up side of the wiring was for the cap to fail in this way and develop a short. so if someone is reading this in the future if a bi rotational wired cap motor suddenly rotates only one direction on both circuits without any change to wiring do a circuit test on the cap first and if it makes both poles make a circuit then that's your problem


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