Hey all,
I want to convert a floor standing fan so I can control the speed and turn
it off from an arduino (eventually to hook in with a home automation system)
If I was using a load like a bulb, I’d use a solid state relay and pwm it,
but I suspect this won’t work with a big Mains motor.
Any thoughts?
-Bob
you’d probably need a varistor… although how does a speed control
work on a normal fan?On 27 May 2012 23:45, Bob Clough parag0n@ivixor.net wrote:
Hey all,
I want to convert a floor standing fan so I can control the speed and turn
it off from an arduino (eventually to hook in with a home automation system)If I was using a load like a bulb, I’d use a solid state relay and pwm it,
but I suspect this won’t work with a big Mains motor.Any thoughts?
-Bob
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Thomas C. Bloor Mob: (+44) 07905646892
tom.bloor@googlemail.com or tom@bloorfamily.net
Homepage: http://tom.bloorfamily.net
How about something like ebay item: 180888584447On 27 May 2012 23:45, Bob Clough parag0n@ivixor.net wrote:
Hey all,
I want to convert a floor standing fan so I can control the speed and turn
it off from an arduino (eventually to hook in with a home automation system)If I was using a load like a bulb, I’d use a solid state relay and pwm it,
but I suspect this won’t work with a big Mains motor.Any thoughts?
-Bob
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Tom,
A varistor is a 2 pin device (looks like a big round ceramic disc
capacitor. It is a device for the protection of mains powered
equipment from High voltage big energy surges. For example:
If lightning were to strike the 110kV Overhead electrical lines the
energy would be transferred through the power lines, through the
switching transformers and through the switchgear all the way until it
got a plug socket. This energy would then pass through the piece of
equipment attached to that plug and without a varistor - blow it up!
The amount of energy involved is in the region of 10 joules. For
those who prefer Volts and Current its a bit more complicated because
this is a pulse and not a constant but if you look at the graphs
concerned the peak voltage applied is 2000V and the amount of current
in the surge is around 3000A! So…not the device for controlling the
speed a fan turns at…but the device for protecting mains powered
equipment from Lighting strikes…I think you meant Variable Speed
Controller or Variac.
Bob,
The eaby item that Andrew found might work…What is it you would
like to control - The speed at which the fan spins or the torque of
the motor? The speed of rotation is controlled by the mains frequency
and is fixed at 50Hz. You can speed this up or slow it down which is
one method of controlling a fan or you can make the fan spin harder
(more power Igor!!)…With cooling fans I believe the vogue is to
control the speed of rotation. Controlling the torque is more for
boat and aircraft propulsion…Although they would work as a
fantastic cooling fan and rubbish removal system…ensure no
appendages are placed near rotating blades!
I would go for varying the frequency of rotation and make a variable
frequency drive for your fan motor. The easiest way to do this is to
generate a sine wave at the frequency of rotation required which can
be varied and then generate the 240V required. Last time I looked at
doing this it was using a simple oscillator, some high power
transistor amplifiers and a high power DC source. We are going to
generate the 240V required at the frequency we want (pseudo AC). I
tried this when I needed a clean 240V generator (not using an
inverter) for powering an oscilloscope in sandy desert like places.
This isn’t particularly easy though and although I got it to
work…it was hard.
I would go down Andrew’s route and by a module.
Cheers
AlexOn 28 May 2012 07:49, Andrew Rose hello@andrewrose.co.uk wrote:
How about something like ebay item: 180888584447
On 27 May 2012 23:45, Bob Clough parag0n@ivixor.net wrote:
Hey all,
I want to convert a floor standing fan so I can control the speed and turn
it off from an arduino (eventually to hook in with a home automation system)If I was using a load like a bulb, I’d use a solid state relay and pwm it,
but I suspect this won’t work with a big Mains motor.Any thoughts?
-Bob
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I want to convert a floor standing fan so I can control the speed and turn
it off from an arduino (eventually to hook in with a home automation system)If I was using a load like a bulb, I’d use a solid state relay and pwm it,
but I suspect this won’t work with a big Mains motor.
I think it depends on the type of motor. Does the fan have an existing
speed control? I’ve popped the back of one of ours (3 speed) and at a
guess I’d say the speed control is done by switching different sets of
windings in the motor in/out, so I don’t think the PWM approach would
work. If it has speed control already it might be easier to hack that
to be digitally controlled rather than trying to directly control the motor.
Alan Burlison
Yea i did mean variac lol. Or a variable transformer 
got the wrong
word… As usual…On May 28, 2012 9:17 AM, “Alexander Lang” alexanderlang1980@googlemail.com wrote:
Tom,
A varistor is a 2 pin device (looks like a big round ceramic disc
capacitor. It is a device for the protection of mains powered
equipment from High voltage big energy surges. For example:If lightning were to strike the 110kV Overhead electrical lines the
energy would be transferred through the power lines, through the
switching transformers and through the switchgear all the way until it
got a plug socket. This energy would then pass through the piece of
equipment attached to that plug and without a varistor - blow it up!
The amount of energy involved is in the region of 10 joules. For
those who prefer Volts and Current its a bit more complicated because
this is a pulse and not a constant but if you look at the graphs
concerned the peak voltage applied is 2000V and the amount of current
in the surge is around 3000A! So…not the device for controlling the
speed a fan turns at…but the device for protecting mains powered
equipment from Lighting strikes…I think you meant Variable Speed
Controller or Variac.Bob,
The eaby item that Andrew found might work…What is it you would
like to control - The speed at which the fan spins or the torque of
the motor? The speed of rotation is controlled by the mains frequency
and is fixed at 50Hz. You can speed this up or slow it down which is
one method of controlling a fan or you can make the fan spin harder
(more power Igor!!)…With cooling fans I believe the vogue is to
control the speed of rotation. Controlling the torque is more for
boat and aircraft propulsion…Although they would work as a
fantastic cooling fan and rubbish removal system…ensure no
appendages are placed near rotating blades!I would go for varying the frequency of rotation and make a variable
frequency drive for your fan motor. The easiest way to do this is to
generate a sine wave at the frequency of rotation required which can
be varied and then generate the 240V required. Last time I looked at
doing this it was using a simple oscillator, some high power
transistor amplifiers and a high power DC source. We are going to
generate the 240V required at the frequency we want (pseudo AC). I
tried this when I needed a clean 240V generator (not using an
inverter) for powering an oscilloscope in sandy desert like places.
This isn’t particularly easy though and although I got it to
work…it was hard.I would go down Andrew’s route and by a module.
Cheers
Alex
On 28 May 2012 07:49, Andrew Rose hello@andrewrose.co.uk wrote:
How about something like ebay item: 180888584447
On 27 May 2012 23:45, Bob Clough parag0n@ivixor.net wrote:
Hey all,
I want to convert a floor standing fan so I can control the speed and
turnit off from an arduino (eventually to hook in with a home automation
system)If I was using a load like a bulb, I’d use a solid state relay and pwm
it,but I suspect this won’t work with a big Mains motor.
Any thoughts?
-Bob
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