Subject: Re: Help with motor speed control
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NNTP-Posting-Date: Thu, 19 Dec 2002 19:01:33 GMT
Organization: Insight Broadband
Date: Thu, 19 Dec 2002 19:01:33 GMT
What!? Pull out your lab supply catalog. There are all sorts of items that
do this sort of thing off-the-shelf.
"Dave White" wrote in message
> We have a device in our lab which is used to rotate glassware in order to
> mix the contents. The shaft needs to rotate at approximately 30 RPM, with
> some control allowance (maybe 20-40 RPM). The company (actually a lone
> engineer) provided this custom made device with a 1/15 HP AC motor
> controlled by a rheostat. We have found that in operation, there isn't
> enough torque to get the glassware to rotate at much more than about 10
> I have been asked to replace the motor and motor control circuit to give
> more power. Looking at our local surplus store, there are a large number
> AC and DC motors, ranging from 1/2 to 2 HP and priced between $20 - $40.
> I'd like to use one of these to control the system. The rheostat control
> seems very inefficient, and I expect I'd use some kind of PWM circuit.
> The DC motor is 120V, 2 HP 4800 RPM and 11.2A. If I were to use PWM,
> the slowest I could run this motor without it stalling?
> There are plenty of washing machine motors rated at 1/2 HP, 1725 RPM.
> this be slowed down easily, and how slow could I go?
> I will be able to include some gearing, probably in the form of a pulley
> system, so all of the slowdown wouldn't need to come from the control
> Any help/advice regarding design, best motor to use, gearing, etc. will be
> GREATLY appreciated - my expertise lies in digital and low power analog
> circuitry, not high power industrial electronics.
> Dave White
> SpectraChrom Software
> Remove the numbers from address for valid e-mail