Reversible Motor, Acme Screw, Limit Switches and my aching head.

Discussion in 'The Projects Forum' started by auburnny, Jul 12, 2010.

  1. auburnny

    Thread Starter New Member

    Jul 12, 2010
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    Hiya. I am having a dilemma and not being an electronics guy, its making my head hurt and it's probably an easy layout.
    I'm using a 115VAC, 1/2 HP Split Phase motor from Grainger (6Z403) which will be coupled with an acme screw. I need this to move a tower from the 0 degree position to a 90 degree position. I have attached a pdf of the tower in the 90 degree position. I'd like to accomplish this by using limit switches as I don't want the unit to keep turning and tear itself apart.

    As I've stated, I'm not an electronics guy but a mechanical one so I'm pretty much at a loss as to how to wire this with the correct switches. It will be wired into a keyed switch on the wall as this is an overhead unit.

    Thanks for your help! Chris
     
  2. auburnny

    Thread Starter New Member

    Jul 12, 2010
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    Ok, I should have been more clear.

    What I'm trying to accomplish is having the motor run until the unit is in the 90 degree position then stop and stay put. And conversely, go from the 90 degree position to the 0 degree position with the use of a 3-position momentary key switch.

    The motor I have chosen is a reversible one and I guess I'd want the limit switches to stop the motor and reverse the motor's direction the next time the key is turned.

    I hope I'm being clear enough. I'm good at reading prints as well and I utilize Solid Works 2010.
     
  3. auburnny

    Thread Starter New Member

    Jul 12, 2010
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    another snapshot of the model in the 0 degree "down" position
     
  4. BMorse

    Senior Member

    Sep 26, 2009
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    you do know you can not just reverse the motor with out physically changing internal wiring connection for the motor power right?
    Dayton Motor Wiring.jpg

    And you will actually have to "stop" the motor before it reaches its end of travel, since the motor does not actually stop on a dime, so you will have to leave a couple of inches for over travel both ways....

    If you want it to "stop at a drop of a dime" you will need this >>http://www.grainger.com/Grainger/items/4Z447?BaseItem=6Z403


    What I usually do with these kind of motors, is I would use a DPDT relay (Rated for the load of the motors you are using) and a Motor contactor, basically the relay will swap those 2 wires for you so the motor can reverse...

    [​IMG]

    B. Morse
     
    Last edited: Jul 12, 2010
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  5. SgtWookie

    Expert

    Jul 17, 2007
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    BMorse touched on contactors, which brings up a safety issue.

    Contactors MUST be used, so if power fails during transit from one state to the other, the tower mechanism will not power up and begin moving when power is restored.

    Otherwise, OSHA will nail you to a cross, and won't use the same holes. :(

    We need to see the datasheet for the motor, or at least the connection diagram in the motor end plate. Request it from Grainger. If they cannot supply it, contact Dayton.

    Like BMorse said, you also need the brake - not only to ensure that the motor stops in a predictable way, but also to ensure that the Acme threaded rod has so much friction that it cannot be turned manually.
    Request the datasheet for the brake unit as well.

    If the datasheets are not in electronic format, then you need to figure out a way to scan and post them. Otherwise, it will be practically impossible for us to give you a viable solution, as motors can be wired in myriad configurations. It would be a shame to burn up nearly $1,000 worth of motor and brake due to a mistake.
     
    Last edited: Jul 12, 2010
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  6. SgtWookie

    Expert

    Jul 17, 2007
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    Unfortunately (or perhaps fortunately), your circuit diagram is so tiny that I cannot make heads nor tails of it.

    Until we are certain of what our OP's motor requires, it would probably be better to remove your schematic. Odds are not in favor of it being correct; and a mistake will cost a considerable amount of time and money to correct. If you don't believe me, go to Schneider Electrics' site, and download a datasheet for a drum switch, and look at the myriad ways that one might have to connect it up to reverse an AC motor.

    BTW, drum switches have become very expensive since they are no longer used in industry. Momentary pushbuttons actuating contactors are the safe way to go now.

    We have to take a cautious approach here.
     
    Last edited: Jul 12, 2010
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  7. auburnny

    Thread Starter New Member

    Jul 12, 2010
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  8. auburnny

    Thread Starter New Member

    Jul 12, 2010
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  9. SgtWookie

    Expert

    Jul 17, 2007
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    We need to see the datasheet for the motor, or at least the connection diagram in the motor end plate. Request it from Grainger. If they cannot supply it, contact Dayton.

    Request the datasheet for the brake unit as well.
     
  10. SgtWookie

    Expert

    Jul 17, 2007
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    OK, but still - whichever motor you plan on using, it must be reversible, and we need to see the internal wiring diagram/schematic.
     
  11. BMorse

    Senior Member

    Sep 26, 2009
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    the wiring diagram I posted in post #5 IS the wiring diagram for the particular motor part number the OP originally posted....

    A contactor and a HEAVY duty DPDT relay will wok for reversing the motor,

    Heavy Duty Relay from www.McMaster.com that I use on motors up to 1 Hp.

    go to bottom of page to the medium amp relays >> http://www.mcmaster.com/#power-relays/=7xxolo

    AC Motor Relay.jpg


    B. Morse
     
  12. auburnny

    Thread Starter New Member

    Jul 12, 2010
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    Data sheet for the motor brake.
     
  13. SgtWookie

    Expert

    Jul 17, 2007
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    Thanks, Brent. I didn't realize the image you posted would get larger if one clicked on it; it was too small for me to see.
     
  14. auburnny

    Thread Starter New Member

    Jul 12, 2010
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    I appreciate the help. I'm trying to figure out what kind of limit switch to use as well...this is a new job and we don't have any electrical guys here. I used to do the logic and work with the PLC builder/programmer but in subsequent places I've worked, the union said this was a big no-no so its been 20 odd years since I've had to do any of this type of work.
     
  15. BMorse

    Senior Member

    Sep 26, 2009
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    well, if this is in a shop environment, you will have to use switches rated for the size of the job (motor current, etc.) so check out some of these, the ones with the lever actuators work well for these types of installation since you really do not want to directly ram into the switch itself, and leaves room for over travel if there is any...

    Most likely a SPDT would work for your application....

    http://www.mcmaster.com/#large-object-limit-switches/=7y288s

    B. Morse
     
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  16. BMorse

    Senior Member

    Sep 26, 2009
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    Ground?? This is not a DC Motor this is AC.... the chassis ground will always be connected to earth ground, the 2 ( that are tied to COM and LINE of the 120VAC mains) internal wires have to be swapped to swap motor direction..

    second, using the relay to apply power to the motor windings is not what it is intended for, you need an AC Motor contactor that is properly rated for the motor load to turn the motor on or off since this motor is rated at 1/2 HP....

    third, cutting corners buy not utilizing properly rated components can lead to failure and could possibly damage property of hurt someone....

    B.Morse
     
    Last edited: Jul 13, 2010
  17. BMorse

    Senior Member

    Sep 26, 2009
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    With AC circuits ground is normally the earth or chassis ground.... COM(Neutral) is used to refer to the return path for the LINE (Hot) power......

    here is a quote from here >> http://www.epanorama.net/documents/groundloop/neutral_ground_separate.html

    I do not really care how you draw anything up as long as it is clear to the OP on what has to be done, for his safety and others........

    B. Morse
     
    Last edited: Jul 13, 2010
  18. Dx3

    Member

    Jun 19, 2010
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    OK. You win. I misused a single word.

    I am obviously not equipped to work at the high standards of this website.
    Good-bye.
     
  19. BMorse

    Senior Member

    Sep 26, 2009
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    You shouldn't take anything anyone says as an insult or a put down, we are all here to learn and help others along the way, nobody is perfect on here, take it as constructive criticism if anything. At least you learned how to properly apply that word correctly :rolleyes: ....

    B. Morse
     
  20. auburnny

    Thread Starter New Member

    Jul 12, 2010
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    Thanks to all for your responses. How would this circuit be drawn? I have attached a simple logic flow chart.
     
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