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Thread: VFD drive help

  1. #1
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    Default VFD drive help

    I wonder if someone can pint me in the right direction here. First this is semi OT as I am not driving a machine tool here, but a V8 engine. I am NOT driving a complete engine but just need to turn the belts of a "display engine" so the load is very slight. My torque wrench does not even move at 1 ft/lb. This is for a museum(NASCAR hall of Fame) and the exhibit is a representation of a dyno room. Visitors will be able to move throttle lever and the engine responds. It needs to idle at about 800 and go up to 6000 rpm(yes I know its less than a real engine, we want to limit the ultimate speed) I can drive this with belts or whatever, the motor does not need to spin up to 6000.

    Can someone recc. a motor and controller to get this done without breaking my budget which is about $750.00?

    Thanks for any help!

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    $750?

    hmmmm . . . and I would assume that this is in a public building that will be inspected by an electrical inspector?

    What kind of line power do you have available? 120V outlet? 240V dryer socket? 480V 3-phase NEMA twist lock with disconnect?

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    Thumbs up Sounds pretty simple...

    SOunds pretty simple, Paul... and without massive mechanical demands and no real 'motion control' required, I'd say the project could be made reality by cruising the nice neighborhoods on trash night, and hitting up the local bearing-shop for the right belt and sheaves.

    First of all, if you're able to mount this WITHIN the demonstration model, cosmetics are totally irrelevant, as long as it fits.

    IF you're putting it on the OUTSIDE, you'll need to devise a method of making the drive motor look like something it ain't... like... an alternator...

    But as for dumpster-diving, find an unloved treadmill, yank the motor and variable-speed DC drive. Make a custom 'control console' that looks realistic, and mount the treadmill motor per above... and I'll bet it'll be just fine for under $120.

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    How about mounting a small 1725 rpm motor in a transmission housing and gearing it up 4:1 to the crankshaft?

    At normal speed this would give you ~7000 rpm crankshaft speed. Low end with a VFD would be about 1/10th of that, or just below your desired idle speed.

    Could probably be done with a fractional-hp motor and a very small VFD. In the 1/3hp range you can get a drive and motor new for ~$300.

    Speed adjustment for the visitors would be trivial. Mount a linear potentiometer on a panel and they could slide the control up and down to control the motor. To set your idle speed you put an adjustable potentiometer behind the panel, connected between the low side of the slide pot and circuit common.

    Add a tachometer and an on/off switch to the panel and you have a nice display.

    - Leigh

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    thanks for the help...the plan is to mount the motor in the tranny housing, run a shaft thru the engine where the crankshaft would be and replace all the actual moving stuff(alternator, oil pump, etc) with sealed bearings so we are not "really" turning the stuff, only the pulleys and belts will turn. The visitor will never be able to tell the difference.

    Can I get a VFD that works on 120 single phase? I have not seen one.

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    Absolutely. I think the 120 volt ones go up to, what
    1.5 hp motor size?

    I bought mine from TECO.

    Jim

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    Can I get a VFD that works on 120 single phase? I have not seen one.
    They're great for smaller (1 hp and under) motors. The drive takes 120 single phase & converts it to 240 three phase. Well under $150 including shipping.

    http://dealerselectric.com/item.asp?cID=&PID=428

    ------------
    Barry Milton

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    Quote Originally Posted by sandiapaul View Post
    Can I get a VFD that works on 120 single phase? I have not seen one.
    I believe there are drives that will take 120-volt single-phase input. They put out 240-volts three-phase.

    I've never seen a 120-volt three-phase motor, nor a VFD that would power such.

    A DC motor is also possible. There are DC speed controls available commonly called VFDs, with appearance and functionality similar to AC VFDs, but since DC has no frequency that's not technically correct.

    - Leigh

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    Default 3 Phase it is

    If the motor is just turning shafts in pullies then very little HP would be needed.

    3 Phase motor of less than 1 HP should be easy to find on the cheap.

    If you use Leigh's suggestion with a 4 to 1 up-speed then you can get some real speed.

    Also the starter motor would be a good place to drive the engine, it would closly match the real function and would allow the transmission housing to be optional in the display.

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    Default Thanks!

    This is all very helpful, thanks much for all your replies! I think I'm good to go now!


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