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  • R2N Motor, going both directions?

     olivero updated 3 months, 3 weeks ago 3 Members · 10 Posts
  • olivero

    Member
    December 4, 2019 at 2:39 pm

    After replacing bearings in an R2N motor, It’s now not working properly (Go me!) and it’s spinning CW and then CCW on occasions, it’s supposed to only go CCW and it’s supposedly not reversible according to the sticker on the motor.

    It uses a start capacitor and a starter relay

    What is supposed to prevent the motor from going in either direction?

    Motor

    https://www.partstown.com/robot-coupe/robr239d

    Cap

    https://www.partstown.com/robot-coupe/robr239d-2

    Start relay

    https://www.partstown.com/robot-coupe/robr239d-1

  • fixbear - ADK NY

    Member
    December 4, 2019 at 3:18 pm

    Did you mark your wires when you took it apart?  Is the relay mounted correctly. They have a up side for gravity.  What you have is a capacitor start, split phase single phase motor. It also will not have full power like it is.

    • olivero

      Member
      December 4, 2019 at 3:24 pm

      Yes, definetley marked it and double checked the wiring.

      It seems like the relay is bad  as it seems that’s what dictates the rotation direction is the start capacitor.

      https://www.eng-tips.com/viewthread.cfm?qid=338598

      Seems like it would make sense, never seen it before, but I guess it could be.

      • fixbear - ADK NY

        Member
        December 4, 2019 at 3:32 pm

        Normally they just hum, but with a Robocoupe there is no load on the motor during testing so it is possible that the start relay isn’t kicking in the cap for the start. You can test the cap, but not the relay very well.  It looks like it may be a potential relay, but it could be a current.

        • olivero

          Member
          December 4, 2019 at 8:47 pm

          We concluded it’s gotta be the starter relay so I ordered one overnight, should be here tomorrow morning.

  • olivero

    Member
    December 5, 2019 at 12:23 pm

    Yup, it was the start relay, it wasn’t engaging the start capacitor.

    Now I know.

    • techtownmayor

      Administrator
      December 5, 2019 at 12:51 pm

      That was a speedy fix! ?

      • olivero

        Member
        December 5, 2019 at 2:32 pm

        That’s how we do it! 🙂

        Or, more like, try to do it.

  • fixbear - ADK NY

    Member
    December 6, 2019 at 6:41 am

    I should expand on this.  The motors used in these are 1725 RPM, 1/2 HP and therefore wound with 4 poles and 2 phases. The start winding coils will be a finer wire than the run coils.   Most of them use a centrifugal switch for the start.  Only the Emerson motor has the solid state starter relay  But what we need to know in the field is that the start winding gets power thru the start capacitor and the relay while the run winding is direct line. If you look at the winding’s in a split phase motor,  you’ll see that the smaller wire winding’s are a few degrees forward of the main winding’s.  This is what gives the motor it’s direction of rotation.  The solid state relays are much the same principle as a potential relay.  They drop power out to the the start winding at a certain voltage.  Centrifugal switch at a certain speed.  Motor inrush current is 17 times full run current at starting.  Because of wire resistance, potential relays monitor the incoming line voltage that starts low and rises as the motor rotation causes a drop in current and a increase in the start winding voltage from magnetic induction. It then drop’s out the start winding from the circuit.

    • olivero

      Member
      December 6, 2019 at 8:36 am

      Yup, I read the spec sheet on the starter and it made more sense, correct with what you are saying as well.

      I didn’t know the start winding is what dictated rotation, but that I am happy to know now as I’m sure it’ll come in handy later.

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