How I fixed it.

[fflintstone]

How I fixed it.

So I wanted to slow down the motor on my drum fan. It had two speeds, super noisy and extra super noisy. I wanted to slow the motor about 30%. Electrical stuff is one of the things I never seem to get the theory behind it. I did a poo load of research on the matter, educated myself. The long and the short of it is there is no GOOD way to slow down a modern single phase AC PSC motor.

I did it the mechanical way. I measured the stock sheave for shaft size and OD, added 33% found a clearance sheave online. Shipping was more than the sheave.

The semi local auto parts store did not have a cogged belt and the one they sold me was a little larger than I had asked for. I had the link belt handy so I threw it on to try it out.

I can now hear myself think when I have the drum fan on.

 

[spotco2]

I like it!

 

[Warrenator]

Now just increase the pitch of the blades and you'll get the same air movement at lower RPM! Same motor power, should be able to swing a coarser fan blade at lower RPM. Probably not possible to tweak it...... Just an idea.

 

[RonaldTenere]

You can try a ceiling fan controller to see what would happen.

 

[racingtadpole]

You can try a ceiling fan controller to see what would happen.

From the look of the motor in the pictures its too big for a ceiling fan controller. You'll either set fire to the controllor or the motor or both

 

[fflintstone]

Now just increase the pitch of the blades and you'll get the same air movement at lower RPM! Same motor power, should be able to swing a coarser fan blade at lower RPM. Probably not possible to tweak it...... Just an idea.

In theory a good idea. However tweaking and rebalancing a fan is not something I am happy trying to do though.
Something too easy to F-up IMO.

It actually still provides good airflow.

 

[fflintstone]

You can try a ceiling fan controller to see what would happen.

After much research, NO, not worth it.

 

[Chaznsc]

What a great idea. Good work, carry on!

 

[theoldwizard1]

...The long and the short of it is there is no GOOD way to slow down a modern single phase AC PSC motor.

Well there IS a "good" way, but not necessarily a cheap way !

What you you think of that belt (I forgot what they are called) ? I heard they are a bit noisy.

 

[Kevin C]

After much research, NO, not worth it.

We ran into this at work... They tried an industrial controller on a large mixer. It kind of works. As you know, the speed of those AC motors is controled by the frequency of the power.

The pulley solution is good.

The only other solution is to run an extension cord from a country with 50 HZ AC. That should drop the speed about 20%.

https://en.wikipedia.org/wiki/Mains_electricity_by_country

List of countries with 50 HZ

 

[fflintstone]

Well there IS a "good" way, but not necessarily a cheap way !

What you you think of that belt (I forgot what they are called) ? I heard they are a bit noisy.

I am not sure what you consider "good" (at any cost) I found no "real" solution to slowing PSC single phase motor in a belt drive application.


As to the” link belt” when I tested it without the fan on it was dead quite, but it didn’t move much air…..

I am going to replace it with a cogged V belt off the internet, the local auto parts raped me on a non-cogged belt and with a small sheave you really need a cogged belt.

 

[Jaynuke]

We ran into this at work... They tried an industrial controller on a large mixer. It kind of works. As you know, the speed of those AC motors is controled by the frequency of the power.

The pulley solution is good.

The only other solution is to run an extension cord from a country with 50 HZ AC. That should drop the speed about 20%.

https://en.wikipedia.org/wiki/Mains_...ity_by_country

List of countries with 50 HZ

However, the cost of the extensions cord would be outrageous, Ha.
The size for the voltage drop would have to be HUGE!!!

 

[e-tek]

From the look of the motor in the pictures its too big for a ceiling fan controller. You'll either set fire to the controllor or the motor or both

Similar, but different: I installed a HD (heavy duty not HomeDepot) rheostat on my shop fan - works great.

 

[InsanePyro]

I wonder if its using more electricity now

 

[fflintstone]

I wonder if its using more electricity now

My WAG would be its using slightly LESS energy due to the motor not working as hard. The PRM of the motor is fixed due to voltage but the slower speed would be less of a load. But WTFDIK?

I don't understand much about electrics, the more I read the more I know and the more I learn there is even more yet I don’t know.

 

[lbmcse]

fflintstone-- you did good! You hit it on the head on your first post that there is no good way to slow down a single-phase motor. 3-phase motors have wiring diagrams allowing for different incoming voltages, but even for these, you can't change the RPM's.

Mechanically is the way to go, and you did well.

As for the last post where it's questioned whether the motor uses more electricity now; the answer is no. As you did, the end-use RPM can be mechanically altered by use of gears (or a pulley in your case), but the electrical input remains unchanged. The difference lies in the stress imparted onto the motor.

With no load, the motor spins at a given RPM dictated by the voltage, number of poles in the motor, and a couple of other variables. Once a load is introduced, unless the mechanical means to change the RPMs is impossibly unreasonable; then the only variable becomes the life of the motor. Slowed down or sped up too much, the motor's windings will overheat. Over time the insulation on those wires will degrade, and the eventual outcome is predictable. The motor burns up.

 

[fflintstone]

fflintstone-- you did good! You hit it on the head on your first post that there is no good way to slow down a single-phase motor. 3-phase motors have wiring diagrams allowing for different incoming voltages, but even for these, you can't change the RPM's.

Mechanically is the way to go, and you did well.

As for the last post where it's questioned whether the motor uses more electricity now; the answer is no. As you did, the end-use RPM can be mechanically altered by use of gears (or a pulley in your case), but the electrical input remains unchanged. The difference lies in the stress imparted onto the motor.

With no load, the motor spins at a given RPM dictated by the voltage, number of poles in the motor, and a couple of other variables. Once a load is introduced, unless the mechanical means to change the RPMs is impossibly unreasonable; then the only variable becomes the life of the motor. Slowed down or sped up too much, the motor's windings will overheat. Over time the insulation on those wires will degrade, and the eventual outcome is predictable. The motor burns up.

WOW! thank you for a great first post and welcome to the forum!

 

[larry_g]

As for the noise factor, are you sure that you are turning the fan in the correct rotation?

lg
no neat sig line

 

[fflintstone]

As for the noise factor, are you sure that you are turning the fan in the correct rotation?

lg
no neat sig line

It ***** it from the rear and blows it out the front. just like every other one I had.

 

[InsanePyro]

My WAG would be its using slightly LESS energy due to the motor not working as hard. The PRM of the motor is fixed due to voltage but the slower speed would be less of a load. But WTFDIK?

I don't understand much about electrics, the more I read the more I know and the more I learn there is even more yet I don’t know.

My thought was just that it might be working harder to spin the weight

 

[rockchucker]

Very nicely done. Great research and onto the only correct answer.

 

[fflintstone]

My thought was just that it might be working harder to spin the weight

If you figure a bicycle in top gear, it takes a great amount of pedal effort to maintain 70 RPM at the crank. If you switch down into a midrange gear, all the sudden petal effort and speed are greatly reduced.

My thought was with a 33 1/3 reduction in speed/work the motor might see a barely measurable drop in amperage. IE if it was pulling say 4.2 amps before it might be pulling 4.18 amps now.

Like I said just my WAG.

I know a great deal of general theory about stuff like electrical and say nuclear fission, far more than the average schmuck on the street, but the more I learn, it becomes woefully apparent that I don’t know squat.

With the popularity of stuff like “dancing with the stars” “E television” “snooki “”kardashians”” hunny boo boo”; being leaps and bounds more intelligent than the general population is really not much of a bar to set for ones self.

 

[Rag Roc]

With the popularity of stuff like “dancing with the stars” “E television” “snooki “”kardashians”” hunny boo boo”; being leaps and bounds more intelligent than the general population is really not much of a bar to set for ones self.[/QUOTE]

LMAO