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  1. #1
    olf20 is offline Aluminum
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    Default Variable Speed for 1/3HP Motor

    We have several fans for our livestock. They are
    220V 1PH either 1/4HP or 1/3HP. We want to vary
    the speed of them to control temperature better.
    We look and find controls that cost $213.00
    @ 7amps max.
    Surely there is something out there that
    can do this cheaper. There is no precision
    here just 25% to 100%.
    Thanks for any help!!
    olf20 / Bob

  2. #2
    robvds is offline Cast Iron
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    Default

    Cheapest solution is to change the motors for 3 phase and buy NOS vfds for them. An ordinary single phase induction motor cannot be run as variable speed, the controls you mention must be specially matched to some particular motor(possibly 3 phase or multi speed) You can also use a control to spoil the input or output of the fan so it moves less air at full speed.
    Rob

  3. #3
    olf20 is offline Aluminum
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    Default

    These motors are just off the shelf Grainger motors.
    We have replaced several of them. The control that
    cost $213 is not for any specific motor. Just 220V.
    They are wired with one leg direct to the motor
    and the other leg is wired thru the control.
    Here is the document for the controller.
    http://www.hired-hand.com/Download.aspx?ID=517&Type=doc
    Thanks for your reply.
    olf20 / Bob

  4. #4
    robvds is offline Cast Iron
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    Default

    Sorry, I was thinking of exhaust fans that use ordinary induction motors, not ''fan'' motors. I think that control is probably a glorified light dimmer, but i will wait for somebody qualified to answer.
    Rob

  5. #5
    DaveKamp is offline Titanium
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    Default Tell me, Bob...

    Hey Bob...

    In looking at that controller, and re-re-reading your question....

    Does that controller simply turn the fan array on and off based on temperature setting? Zooming in close to the controller board doesn't reveal any hints of substantial componentry.

    With the stirring-fan motors I've seen, they're an arrangement that will SOMETIMES respond okay to a thyristor-chopper type control, like the 'dimmer' type that Rob mentions, but if you're running an array of stirrers in your pen, and they're on 240v line, you can't just use a 120v dimmer.

    One COULD, however, employ a gadget that uses a solid-state relay and switches power on and off... a few cycles on, and then a few off... so that the motors are never really running 'at speed'... the downside is that some motors will get really hot under those circumstances.

    If I were faced with this situation, I'd probably consider something half-luddite... take the motor out, and install a shaft on each frame so the fan blades could be belt-driven from a lineshaft, and then put a 1hp 3-phase motor at some convenient location, and VFD that bugger, and wire the VFD to a thermistor sensor, so that fan speed increases with ambient temperature, and put the thermistor in such a location that airflow provides direct feedback to the thermistor's sense location, which means the temperature will attempt to be made self-regulating and constant based on your setpoint.

  6. #6
    olf20 is offline Aluminum
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    Default

    Their diagram just show one application. Our is different, one fan on each
    side of the building. I talked to the tech on this control and he said it did
    not matter how many motors were hooked up as long as the total current
    did not exceed the max for the controller.
    Thanks for you responses!
    olf20 / Bob

  7. #7
    YoungDen is offline Cast Iron
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    That controller is reducing voltage. That would be ok on a hand drill or something like that, but a plain motor will try to run at full speed and starve for voltage if the hertz are still 60.
    I would point you toward a VFD and 3 phase motor.

    1/2HP, TB Woods, Model SE1C2S005H01, 230 Volt 1 Phase Input, variable frequency drive, variable frequency drives, ac drive, vfd, afd, frequency drive, drive, inverter, adjustable speed drive - Dealers Industrial Equipment, LLC

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    RELIANCE AC MOTOR P56H0302N-PT 1/2HP 230/460VOLTS ***NNB*** | eBay

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    Shop carefully, there is a lot of stuff around.

  8. #8
    olf20 is offline Aluminum
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    Default

    These are used in a lot of farm applications. We have had other
    controllers that vary the speed of the fans as well as control
    other functions.
    The three phase option is a little more difficult because of wiring
    and getting motors to fit inside our fan enclosures. Many of the
    farm fans have a complete fiber glass or stainless steel housing
    and the motor and fan fit inside.
    Thanks again for all input.
    olf20 / Bob

  9. #9
    Jraef's Avatar
    Jraef is offline Titanium
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    Default

    This will work for Shaded Pole motors, which is what those Stir fans are, just like your paddle ceiling fans. From the little bit of info they provide on that controller, I'd guess that this is nothing more than a simple triac controller with a bypass switch, basically a 12A dimmer and a parallel switch rated for 12A. You could make the same thing out of off-the-shelf parts if you were so incliuned. 12A at 230V is roughly 2000W worth of motor load, so that thing would be overkill for one single motor of 1/3HP. An off-the-shelf fan speed control would be a lot less expensive. But you will need to pay attention to how you house it, the points they make in their data sheet about ambient conditions are valid.

    Don't use just any lighting dimmer, some of them are not suitable for motor loads.

    Fan Speed Control, 3 A - Fan Speed Control - HVACR and Appliance Controls - 1DGV1 : Grainger Industrial Supply

  10. #10
    olf20 is offline Aluminum
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    Default

    Thanks for your reply Jraef. So I would just wire it as
    per the diagram in the PDF file, on one leg of the
    220? L1 ----- O ------XXXX------- L2
    ---------- Motor -- Controller
    Also thanks for the link.
    Would one of the other speed controllers that have
    a higher current / watt rating give us a little over kill
    to help in the heat of the summer?

    Thanks olf20 / Bob

  11. #11
    Jraef's Avatar
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    Default

    Quote Originally Posted by olf20 View Post
    Thanks for your reply Jraef. So I would just wire it as
    per the diagram in the PDF file, on one leg of the
    220? L1 ----- O ------XXXX------- L2
    ---------- Motor -- Controller
    Also thanks for the link.
    Would one of the other speed controllers that have
    a higher current / watt rating give us a little over kill
    to help in the heat of the summer?

    Thanks olf20 / Bob
    Higher current ratings do help in high ambient, but only to a point. Put it in as big of a box as you can, give it lots of room to dissipate and keep the entire box out of direct sun. Don't let it get wet either. Water + electricity = bad.

  12. #12
    olf20 is offline Aluminum
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    So it does not matter the controller is 110V and our
    motors are 220V?
    Thanks again!
    olf20 / Bob

  13. #13
    olf20 is offline Aluminum
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    Default

    Just trying to get the voltage clarified.
    Thanks olf20 / Bob

  14. #14
    DaveKamp is offline Titanium
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    Default Den-

    Den, the reason why Bob won't be changing the motors in the fans, is because the fan motor is specific to the fan... built into the framework, not at typical multipurpose motor.

  15. #15
    JST's Avatar
    JST
    JST is offline Diamond
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    Default

    Quote Originally Posted by Jraef View Post
    This will work for Shaded Pole motors, which is what those Stir fans are, just like your paddle ceiling fans.
    At that power, I'd be more inclined to think PSC motors...... but no matter, the very same controller works for either type.

    For that matter, the maker of the TB woods units also makes single phase VFDs which will work on any motor that the controller shown would.

    The dimmer types all ONLY work on a fan type load..... they relay on teh fact that the shaded pole and PSC motors can tolerate lots of slip, and that the fan load varies with speed..... If there were a constant load, or no load, the motor would either not run, or it would go at nearly full speed.

    With a single phase VFD, it can be made to go at most any speed more or less regardless of load.

    here is the manufacturer in question with single phase VFDs:

    Invertek Drives AC Drives, Drives, Inverters, and Control Systems
    Last edited by JST; 02-18-2012 at 03:36 PM.

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