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simple electrical question

This isn't really an electronics question, but I can't find a more suitable newsgroup to ask in.

I have a motor from an oil furnace's blower that I would like to run at approximately half its normal speed.

I read that a "Variac" could be used to slow it down.

I was wondering why a dimmer switch for a light couldn't be used instead. I would rather spend $2 than $100. :-)

Here are the specs from the label on the motor:

Emerson HP: 1/3 V: 115 A: 5.4 RPM: 1750 Hz: 60 SF: 1.35 SFA: 6.4

I vaguely remember from high school physics that watts = amps * volts, so we would be looking at just over 600 watts.

I have never personally seen a dimmer switch connected to a light fixture with 6 light bulbs, but perhaps it is still possible....? Or would it melt the dimmer switch into a puddle in my hands.

Thanks................................. Stephanie D.

Reply to
spikchik69
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This motor is not suited for speed control. You would have to alter the frequency of the power supplied. Neither a variac nor a lamp dimmer will work. A lamp dimmer puts out DC and AC and is very bad for speed control.

Look for an AC/DC motor or a PSC motor.

Reply to
Homer J Simpson

Thanks for your reply.

BTW, you're saying that the dimmer switch that dims the 100 watt bulbs in my living room puts out DC? I guess I knew less about electrical stuff than I thought!! :-) ..sd

Reply to
spikchik69

It's AC but it is asymmetrical so there is a DC component. If you use it on a fan or similar motor it will be very noisy or burn it out. There are special fan versions for this usage.

Reply to
Homer J Simpson

This is probably asking a lot, but do you happen to know a specific brand and model number that would replace the above motor? Failing that, can you recommend a good site where I could get it online?

Thanks...... ..sd

Reply to
spikchik69

What's the purpose of the motor? Is it on a burner?

Reply to
Homer J Simpson

It isn't possible to tell you what to use without knowing what you have . . . there are thousands of types

You'd have to get all the specifications for the motor - physical size mounting shaft diameter and length rotation direction. If it is a standard frame size that helps. If you have access to Graingers

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They have a good selection of motors, an appliance wholesaler is another option, a lot of companies specialize in surplus motors.

Check the name plate data of the one you have that may give you some information. And wouldn't it be a shame to replace it to find out the old one is really a two speed motor?

One assumes you don't intend to run the motor inside the furnace at half speed - that could have some other consequences.

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Reply to
default

Hi,

Its not possible to sacle down speed of a Electric Motor by using a Dimmer. This will lead to overload a motor resulting into burning. An appropiate method is to use an Variable Frequency Drive to scale down the speed and still get correct Power output.

Please contact any VFD Supplier like Allen Bradely, Simens, Danfoss and host other available.....

Please provide the supplier with Motor Specificati> This isn't really an electronics question, but I can't find a more

Reply to
Raghav Holkar

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