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Speed control of exhaust fan

J

John Dunkley

Jan 1, 1970
0
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
 
P

Phil Allison

Jan 1, 1970
0
"John Dunkley"
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.


** A variac will likely work just fine.

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





........ Phil
 
T

Trevor Wilson

Jan 1, 1970
0
John Dunkley said:
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.

**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.
 
B

Brian Goldsmith.

Jan 1, 1970
0
Trevor Wilson said:
I would be grateful for some advice on what is the most efficient way to
speed control an exhaust fan?

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.
 
K

Kr

Jan 1, 1970
0
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.
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
 
T

Trevor Wilson

Jan 1, 1970
0
Brian Goldsmith. said:
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!!!

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