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  1. #1
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    3-phase motor Speed Control

    I have a chip conveyor on my Hyundai-Kia Turning Center and I would like to adjust the speed of the conveyor to limit coolant loss. The motor is a 3-phase induction 240V 1.0A. Does anyone know of an easy/inexpensive way to do this?

    Thanks for your ideas.

    Joseph

  2. #2
    Super Moderator Al_The_Man's Avatar
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    The common most popular way is with a VFD, if you do a search here you should find enough information.
    If you want a one-time speed fix, then a reduction of some kind could be done.
    Al.
    CNC, Mechatronics Integration and Custom Machine Design

    “Logic will get you from A to B. Imagination will take you everywhere.”
    Albert E.

  3. #3
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    Dirt cheap and includes potentiometer for speed adjustment:

    http://web1.automationdirect.com/adc..._VAC)/GS1-20P2

    Matt

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    Thank you for your comments, Matt and Albert. The one you found, Matt, was about $30 cheaper than the cheapest I had found.

    Next question, where does it get hooked up? The current configuration is as follows:

    3-phase 240V from Lathe --> Siemens Sirius Contactor --> Siemens Overload Relay (this branches out to another Contactor which supplies the Forward, Reverse and Stop switches) --> 3-phase Induction 240V 1.0A Motor

    Thanks Again,

    Joseph

  5. #5
    Super Moderator Al_The_Man's Avatar
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    The only thing I would keep out of those is the contactor to be enabled by the E-stop, switching the 3 phase input to the VFD, the O.L and reversing contactors or switches can be removed from the power wiring.
    Speed, Fwd, Rev is done by low level Control.
    The VFD takes care of O/L's as well.
    3 phase in to the contactor, 3 phase out to the VFD.
    To keep radiated noise down, I would pull the motor wires and make sure they are twisted together, if not already, also make sure you take a ground from VFD to motor frame.
    And of course, suitable independant fusing before the contactor.
    Al.
    CNC, Mechatronics Integration and Custom Machine Design

    “Logic will get you from A to B. Imagination will take you everywhere.”
    Albert E.

  6. #6
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    Like AL said keep contactor for e-stop and power shut off. If you have a 3push-button start-rev-for you can use 2 small DPDT relays for forward-rev. Use 1 N. O. cantact to pull in forward or rev and the other N. O. for the latch. Use the N. C. contacts for your lockout circuit. Use the pot for speed control. The instruction book has diffrent examples which you can copy from.

    I have wired up 3 drill presses with VFDs and the guys were very happy with the results.

  7. #7
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    Thanks for all the help jschmitt.

    A couple more questions. I am going to put this in a separate NEMA enclosure. Will i need to put a fan in the enclosure? Will two vents work? If I need a fan, can I power it from the VFD?

    Thank You,

    Joseph

  8. #8
    Super Moderator Al_The_Man's Avatar
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    It depends somewhat on the usage, they do tend to get warm when close confined, usually the manual shows the enclosure spacing required.
    Later if you feel the need for a fan, I would get a 6" Muffin Fan, 240v 1 phase across two of the incoming supply phases.
    Al.
    CNC, Mechatronics Integration and Custom Machine Design

    “Logic will get you from A to B. Imagination will take you everywhere.”
    Albert E.

  9. #9
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    Probably depends on how big the enclosure is. The VFD is pretty small so it will not put out too much heat. If the enclosure is big enough, it will cool itself enough. If not, you will need some vents/fan to keep the air moving. The spec sheet for the VFD probably specifies a maximum ambient temperature for 100% output current. Its normally around 40 degrees C. If you want, you could test it by measuring the temperature inside the enclosure and add appropriate cooling if it gets too hot. I would probably play it safe and at least install a couple vents so that natural convection can keep some air flowing through the enclosure. If you decide to use a fan, you can buy a 220V model and just connect it to two of the three phases powering the VFD. You could also use one of the outputs from the VFD to turn the fan on and off so the fan only runs when the VFD is enabled.

    Matt

  10. #10
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    Thanks, Al. The unit runs pretty much nonstop, 24/7. No way to use a small DC computer fan? The reason I ask is because I see a +10V output terminal on the VFD.

    Joseph

  11. #11
    Super Moderator Al_The_Man's Avatar
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    I would not be inclined to use the 10v terminal as they do not generally supply alot of current, it is probably intended to feed the speed pot.
    If a 120v type is easier to obtain, you could run it off a nearby outlet.
    Al.
    CNC, Mechatronics Integration and Custom Machine Design

    “Logic will get you from A to B. Imagination will take you everywhere.”
    Albert E.

  12. #12
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    Quote Originally Posted by joseph10s View Post
    Thanks, Al. The unit runs pretty much nonstop, 24/7. No way to use a small DC computer fan? The reason I ask is because I see a +10V output terminal on the VFD.

    Joseph
    Al has it right again. The +10 feeds the speed pot and provides for your stop-for-rev circuit. We used the enclosure that housed the for-rev contactors, I'm guessing 16 x 16 x 10. We used braking resitors to eat up emf and slow the motor down quickly. we have not had any problems with heat. It has been fairly trouble free.

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