NMB Minebea fan - how to regulate speed...?

[gronn-overledning]

Possible to regulate speed of this fan?

Is there some way to regulate speed of this fan?
All I need is something lower than full speed, and maybe 2-3 lower speeds


A) The easiest for me is to make some arrangement with resistors (I have some high-power resistors, like 5 og 10 Ohms.....25 or 50 Watt).

B) Can two fans be connected in serial?

C) Eventually use some elecronics...PWM ??

I have too little experience with modern modern "shelf-electronics", so I guess I will get quicker answer here...

Thanks in advance, for help.



NMB Minebea Model 5915PC-23T-B30  techical specs

https://www.allaboutcircuits.com/electronic-components/datasheet/5915PC-23T-B30-A00--NMB/

[Circlotron]

I have had good results with fans like that by putting about 2 to 4uF capacitor in series with the motor. For best safety should be a 250VAC X2 capacitor. X2 means it is rated for direct connection across the mains, although that is not happening here. Caps will get an easy life because they are protected by the motor inductance.

Two fans can be connected in series, no problem. Ideally they should be identical fans.

[mariush]

Maybe using a triac with an optocoupler with zero crossing detection to turn on and off the fan for periods of time.

You could try one of those classic light dimmers that cut the peak AC voltages...

Next easiest would probably be to get a toroidal transformer designed for 230v - 230v and unwind the secondary winding to make a bunch of steps ex 155v - 170v - 185v - 200v - 215v - 230v then you could use  some mechanical relays to switch between windings.

If you don't want to rewind transformers, maybe get 1 transformer that does 230v - 120v and then a one or two transformers that have 2-4 24v/36v/48v secondaries and connect the secondaries in series and switch between taps to get a lower AC voltage.

With 35w per fan, you're looking at low currents like 0.1A so the toroidal transformers won't need to be big ...
 
ex
16$ for 115/230v to 120v AC  56VA  : https://www.digikey.com/en/products/detail/triad-magnetics/FD7-120/4878685

24$ for 115/230 to 120v AC 100VA : https://www.digikey.com/en/products/detail/triad-magnetics/FD8-120/4878695

29$ for 100V, 120V, 200V, 240V to Parallel 120V, Series 240V  100VA :   https://www.digikey.com/en/products/detail/talema-group-llc/0100MD-1-003/4289485

add a second transformer to add to the base 120v AC ... ex  https://www.digikey.com/short/mbr58btv



The first may be enough for two fans in parallel, the 100VA ones should do 3 in parallel.

[David Hess]

A) The easiest for me is to make some arrangement with resistors (I have some high-power resistors, like 5 og 10 Ohms.....25 or 50 Watt).

That will work, but a high voltage film capacitor like Circlotron suggests will work better because there will be nothing lost to heat.

B) Can two fans be connected in serial?

Yes, but the speeds may be too slow or the fans might not start.

C) Eventually use some elecronics...PWM ??

A phase control dimmer will work, but perhaps not very well.  A variac will work better.

[gronn-overledning]

Thanks for advice.
Looks like easiest and cheapest trying the capacitor.
I have to buy one....or maybe looking through the electronics scap container at work. Lots of electronics thrown away there.

Forgot to tell what my project is:

I will move heated air from the living room where the heating pump and wood stove (oven) is placed, and move the air somewhere into the the kitchen. Already made the 15 cm hole in the wall....1 year ago 

I the kitchen there is heating cables in the floor, but I dont use it (Norway is cold and electricity stolen from us...prices went up 3-4 years ago).
Both rooms are a bout 35 sq.metres (about 350 sq-feet...each?).

So because I will use 1 vent-duct (pipe) about 15 cm  (6 inch), I actually need just 1 fan).

Will the capacitor "slow" down the current, so higher capacity acting kind of higher resistance - less current?

Thanks again.

[Circlotron]

Will the capacitor "slow" down the current, so higher capacity acting kind of higher resistance - less current?

Thanks again.

At 50Hz a 1uF capacitor will have an impedance (AC "resistance") of 3183 ohms. Double the capacitance will halve the impedance to 1591 ohms.

Not enough capacitance and the motor won't get enough power to run.
Too much capacitance and the motor will simply run at full speed.

[David Hess]

Will the capacitor "slow" down the current, so higher capacity acting kind of higher resistance - less current?

It works the opposite way.  Higher capacitance results in lower reactance, so the motor runs faster.  The reactance is inversely proportional to the capacitance.

Rc = 1 / ( 2 Pi F C )

[NiHaoMike]

The power saved would be minimal, have you considered adding a filter to add restriction while filtering the air?

[gronn-overledning]

The power saved would be minimal, have you considered adding a filter to add restriction while filtering the air?

I have thought about making a filter-casing (dust collector).
Its not about saving energy, but reduce possible fan-noise/motor-noise.

Now you made an idea into my head.
If I make a filterbox of wood, it will make space for 2 fans side by side.

Not made the decision yet, to have the fan blow heated air into the kitchen, or transfer (colder) kitchen-air into the heater-pump area, thus forcing the heated air into to kitchen door....as return-air.


I actually dont understand the sentence - "...adding a filter to add restricton, while filtering....".
I guessed you meant air-filter/dust filter...?