Speed control of exhaust fan

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I would be grateful for some advice on what is the most efficient way to
speed control an exhaust fan?

Not knowing much about motors, it is a 240 volt unit 0.45 amps.

JD



Re: Speed control of exhaust fan



"John Dunkley"

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** A variac will likely work just fine.

 So might a phase control dimmer designed to control fan motors.





.......   Phil



Re: Speed control of exhaust fan


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Electrical wholesaler will have plenty. Try this Clipsal one, but plenty
of others.

http://updates.clipsal.com/ClipsalOnline/ProductInformation.aspx?CatNoC2%032E500F&ref =

David



Re: Speed control of exhaust fan



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**Assuming the motor is a synchronous type, your chances are limited. PA's
idea of a VariacT is ideal, but expensive and bulky. I know people who have
put a lamp in parallel with the motor and used a standard light dimmer. I
can't guarantee the results, but it should work. Another good way is to
place the motor in series with a bridge rectifier (and the mains supply).
Across the DC connections of the bridge, connect a MOSFET (suitable rated
and heat sinked, of course) and vary the Gate Volts to get speed control
that way. The advantage is the motor can be varied over a very wide range.


--
Trevor Wilson
www.rageaudio.com.au



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Re: Speed control of exhaust fan




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Assuming the motor is a synchronous type, your chances are limited.


***** Wilson,you must be joking,an exhaust fan with a synchronous motor,the
mind boggles!!!

Brian Goldsmith.




Re: Speed control of exhaust fan


On Thu, 13 Jul 2006 10:02:00 GMT, "Brian Goldsmith."

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All domestic mains powered exhaust fans I have ever seen use a simple
shaded pole AC motor.  

I think a synchronous motor would be a bit over the top for an exhaust
fan :)

http://en.wikipedia.org/wiki/Shaded_pole_motor

Re: Speed control of exhaust fan



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**Call it a brain fart. Of course a standard induction motor will be the
type used. My other comments and suggestions remain.


--
Trevor Wilson
www.rageaudio.com.au



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