Hi, I have few dozens of cheap small 20watt blower in my projects, do you think using light dimmer is a good idea ?, its can works but, it is will be get long lifespan that way ?, and make me more cautious is if I dim it to low before zero its just humming and not running, while its a public area project that anyone can adjust its speed it is a bad idea to use light dimmer to adjust 20w blower fan speed for a few dozens which needs to be adjusted individually ?, or is there any other idea ?, I has try using auto transformer too, but seems the cost is too high and is that will be reliable too ?, as there is no humming problem using auto transformer, I just use multiple tap that is connected to a selector switch and just about seven speed variation, but I can just use one huge auto transformer for a few dozens of those small blower and they will got their own individual selector switch

 

What type of motor is it? (Synchronous, induction, universal) and is the supply AC or DC and what voltage?

 

What type of motor is it? (Synchronous, induction, universal) and is the supply AC or DC and what voltage?

Unknow generic chinese motor, just about $15 pricetag each, 220v AC, and I test it 240v AC for a few minutes still fine

 

Unknow generic chinese motor, just about $15 pricetag each, 220v AC, and I test it 240v AC for a few minutes still fine

But the type of motor (synchronous, induction or universal) makes the difference as to whether you can speed-control it.
If it has windings only on the stator, then it is synchronous or induction. If the rotor has permanent magnets it is synchronous,
If it has brush gear and windings on the rotor then it is universal.
Only universal motors can be controlled successfully by changing the voltage (using a dimmer)
Reducing the voltage to an induction motor will reduce the torque and increase the slip making it run more slowly, but is not guaranteed to work.

 

But the type of motor (synchronous, induction or universal) makes the difference as to whether you can speed-control it.
If it has windings only on the stator, then it is synchronous or induction. If the rotor has permanent magnets it is synchronous,
If it has brush gear and windings on the rotor then it is universal.
Only universal motors can be controlled successfully by changing the voltage (using a dimmer)
Reducing the voltage to an induction motor will reduce the torque and increase the slip making it run more slowly, but is not guaranteed to work.

It has no capacitor and no nameplate for it, what do you think ?, also as I said before, its has been tested using dimmer and works but humming if to low voltage, its speed seem proportional too, but not yet check using tachometer

 

Like most small AC mains powered fans/motors, predominantly shaded-pole (shunt) field motor.
They are the most inefficient of AC motors, and generally only used for light (fan) style loads.

 

I just use multiple tap that is connected to a selector switch and just about seven speed variation, but I can just use one huge auto transformer for a few dozens of those small blower and they will got their own individual selector switch

That should work.

You can also use film capacitors (typically a few µF) in series with the motor to control the speed, but that basically requires a capacitor for every speed, for each blower.

 

Unknow generic Chinese motor, just about $15 price tag each, 220v AC, and I test it 240v AC for a few minutes still fine

You may have been better off using Chinese DC brushed motors, One of the Chinese makes is Johnson and often used in power tools etc.
The Chinese have the rare earth magnet market pretty sewn up so they should be fairly good motors.
Also a make used frequently in TM's which is a well made motor.
But for small motors you would have got them for the same price as you paid, another plus is many now run with ball bearings ..

 

Another good source of LV DC motors is the automotive scrap yards!

 

Quote from post #1: (has been edited)
Hello,

I have several dozen inexpensive, small 20-watt blowers in my projects. I am considering using a light dimmer to control their speed. While it is possible to use a light dimmer, I am concerned about its potential impact on the blower’s lifespan. Additionally, I am worried that if I dim the blower to a low setting before it reaches zero, it will only hum rather than operate.

Since this is a public area project that will be accessible to anyone, it would not be practical to use a light dimmer to adjust the speed of each blower individually. I am also considering using an auto transformer, but the cost is prohibitive, and I am unsure of its reliability.

As there is no humming issue with using an auto transformer, I have considered using multiple taps connected to a selector switch to provide seven speed variations. However, I could potentially use a single large auto transformer to power all of the blowers, each with its own individual selector switch.

The above comment was edited using AI (Apple Intelligence) to make it easier to follow. I realize that for @meowsoft, English is a second language.

Paragraph 1: Not sure if a light dimmer will be happy with a motor. You DID say it worked but with hum. Especially depending on what kind of motor it is. As for hum - if the motor is spinning and you lower the speed it should continue to spin until there is insufficient current to drive the motor. Hum may be a minimal issue. But I think the hum is coming from the type of dimmer you're using. The dimmer is chopping the AC sine wave lower and lower. Eventually you get to a point where there is barely any sine wave at all. THAT is what makes motors hum. At least that's what I think.

Paragraph 2: An auto transformer (or AT) would need to be able to handle the full load of all the fans if that's what you're thinking. If you want an AT for each fan then the power requirements will be much smaller. But now you're buying even more AT's

Paragraph 3: You want to introduce multi-tapped transformers for individual speed control and use an AT for overall speed control? What if one fan needs to run low speed while another needs to run high speed? If the AT has limited the max speed then it might not be possible to run the high speed fan at full speed.

 

Shaded pole AC motors are notorious for dropping out of run at low RPM, generally the worst kind for RPM control.

 

Quote from post #1: (has been edited)
Hello,

I have several dozen inexpensive, small 20-watt blowers in my projects. I am considering using a light dimmer to control their speed. While it is possible to use a light dimmer, I am concerned about its potential impact on the blower’s lifespan. Additionally, I am worried that if I dim the blower to a low setting before it reaches zero, it will only hum rather than operate.

Since this is a public area project that will be accessible to anyone, it would not be practical to use a light dimmer to adjust the speed of each blower individually. I am also considering using an auto transformer, but the cost is prohibitive, and I am unsure of its reliability.

As there is no humming issue with using an auto transformer, I have considered using multiple taps connected to a selector switch to provide seven speed variations. However, I could potentially use a single large auto transformer to power all of the blowers, each with its own individual selector switch.

The above comment was edited using AI (Apple Intelligence) to make it easier to follow. I realize that for @meowsoft, English is a second language.

Paragraph 1: Not sure if a light dimmer will be happy with a motor. You DID say it worked but with hum. Especially depending on what kind of motor it is. As for hum - if the motor is spinning and you lower the speed it should continue to spin until there is insufficient current to drive the motor. Hum may be a minimal issue. But I think the hum is coming from the type of dimmer you're using. The dimmer is chopping the AC sine wave lower and lower. Eventually you get to a point where there is barely any sine wave at all. THAT is what makes motors hum. At least that's what I think.

Paragraph 2: An auto transformer (or AT) would need to be able to handle the full load of all the fans if that's what you're thinking. If you want an AT for each fan then the power requirements will be much smaller. But now you're buying even more AT's

Paragraph 3: You want to introduce multi-tapped transformers for individual speed control and use an AT for overall speed control? What if one fan needs to run low speed while another needs to run high speed? If the AT has limited the max speed then it might not be possible to run the high speed fan at full speed.

I has been tried with about only very low dimmer position, then its hum and when I make experience to left it for a few days in that state, motor gets burnt, which is a bad idea if non technical user just set dimmer to be very low but not turned off yet so its can destroy it

 

Quote from post #1: (has been edited)
Hello,

I have several dozen inexpensive, small 20-watt blowers in my projects. I am considering using a light dimmer to control their speed. While it is possible to use a light dimmer, I am concerned about its potential impact on the blower’s lifespan. Additionally, I am worried that if I dim the blower to a low setting before it reaches zero, it will only hum rather than operate.

Since this is a public area project that will be accessible to anyone, it would not be practical to use a light dimmer to adjust the speed of each blower individually. I am also considering using an auto transformer, but the cost is prohibitive, and I am unsure of its reliability.

As there is no humming issue with using an auto transformer, I have considered using multiple taps connected to a selector switch to provide seven speed variations. However, I could potentially use a single large auto transformer to power all of the blowers, each with its own individual selector switch.

The above comment was edited using AI (Apple Intelligence) to make it easier to follow. I realize that for @meowsoft, English is a second language.

Paragraph 1: Not sure if a light dimmer will be happy with a motor. You DID say it worked but with hum. Especially depending on what kind of motor it is. As for hum - if the motor is spinning and you lower the speed it should continue to spin until there is insufficient current to drive the motor. Hum may be a minimal issue. But I think the hum is coming from the type of dimmer you're using. The dimmer is chopping the AC sine wave lower and lower. Eventually you get to a point where there is barely any sine wave at all. THAT is what makes motors hum. At least that's what I think.

Paragraph 2: An auto transformer (or AT) would need to be able to handle the full load of all the fans if that's what you're thinking. If you want an AT for each fan then the power requirements will be much smaller. But now you're buying even more AT's

Paragraph 3: You want to introduce multi-tapped transformers for individual speed control and use an AT for overall speed control? What if one fan needs to run low speed while another needs to run high speed? If the AT has limited the max speed then it might not be possible to run the high speed fan at full speed.

Dimmer switches is pretty much same with this https://chint.co.uk/product/slm-1442bcbm/

 

Unfortunately no complete documentation by Chint as usual, not like Schneider Electric, or Siemens which is have tons of documentation

 

If the motors get hot when turned all the way down then there's current flowing through the motors, even if they're not moving. So I'd recommend NOT using light dimmers.
Here's a fan speed controller from Amazon.
https://www.amazon.com/Lutron-FS-5FH-DK-Electronics-Fan-Speed-Control/dp/B000BPHJDU/ref=sr_1_1
This might be better. Likely not going to make the noise the ones you're using now. As for ON / OFF function I don't know how it works. Maybe you turn the dial all the way till it clicks, maybe you push it in like a button.

 

That is the cost of running a low efficient motor, the inefficiency can be as low as 35% on shaded pole motor, and they generally stall out early.

 

If the motors get hot when turned all the way down then there's current flowing through the motors, even if they're not moving. So I'd recommend NOT using light dimmers.
Here's a fan speed controller from Amazon.
https://www.amazon.com/Lutron-FS-5FH-DK-Electronics-Fan-Speed-Control/dp/B000BPHJDU/ref=sr_1_1
This might be better. Likely not going to make the noise the ones you're using now. As for ON / OFF function I don't know how it works. Maybe you turn the dial all the way till it clicks, maybe you push it in like a button.

Its like this
0%, turned off
10% - 40%, humming, and after few days got burnt
50% - 100%, running like usual and fine for even a few weeks tested

But the one will be used it is a non trained user, so its impossible to tell them to not set the dimmer for less than 50%

 

Its like this
0%, turned off
10% - 40%, humming, and after few days got burnt
50% - 100%, running like usual and fine for even a few weeks tested

But the one will be used it is a non trained user, so its impossible to tell them to not set the dimmer for less than 50%

I has try to modify it phisically adding a cross in the switch to prevent in being turned less than 50%, but seems my physical knobs modification is not reliable enough

 

That is the cost of running a low efficient motor, the inefficiency can be as low as 35% on shaded pole motor, and they generally stall out early.

Yes, in my own lab, I use a smart solution, using a generic cheap chinese blower fan but replace its motor with Siemens motor and its still running for more than one decade

 

Quote from post #1: (has been edited)
Hello,

I have several dozen inexpensive, small 20-watt blowers in my projects. I am considering using a light dimmer to control their speed. While it is possible to use a light dimmer, I am concerned about its potential impact on the blower’s lifespan. Additionally, I am worried that if I dim the blower to a low setting before it reaches zero, it will only hum rather than operate.

Since this is a public area project that will be accessible to anyone, it would not be practical to use a light dimmer to adjust the speed of each blower individually. I am also considering using an auto transformer, but the cost is prohibitive, and I am unsure of its reliability.

As there is no humming issue with using an auto transformer, I have considered using multiple taps connected to a selector switch to provide seven speed variations. However, I could potentially use a single large auto transformer to power all of the blowers, each with its own individual selector switch.

The above comment was edited using AI (Apple Intelligence) to make it easier to follow. I realize that for @meowsoft, English is a second language.

Paragraph 1: Not sure if a light dimmer will be happy with a motor. You DID say it worked but with hum. Especially depending on what kind of motor it is. As for hum - if the motor is spinning and you lower the speed it should continue to spin until there is insufficient current to drive the motor. Hum may be a minimal issue. But I think the hum is coming from the type of dimmer you're using. The dimmer is chopping the AC sine wave lower and lower. Eventually you get to a point where there is barely any sine wave at all. THAT is what makes motors hum. At least that's what I think.

Paragraph 2: An auto transformer (or AT) would need to be able to handle the full load of all the fans if that's what you're thinking. If you want an AT for each fan then the power requirements will be much smaller. But now you're buying even more AT's

Paragraph 3: You want to introduce multi-tapped transformers for individual speed control and use an AT for overall speed control? What if one fan needs to run low speed while another needs to run high speed? If the AT has limited the max speed then it might not be possible to run the high speed fan at full speed.

Is my english not good enough ?, should I learn from AI ?