how to control speed of single phase motor 5

[themroc]

I am chemical engineer and we need to set up an experimental rig in order to meassure pressure drop in gas flows.
For this purpose we use use a 2.2kW single phase air blower with a constant fan speed and gas flow.
We would like to make this gas flow variable, that means change the motor speed continiously.
What kind of electronic device do we need for this.
Is a phase angle regulator the right device.
Can someone give advice on devices and where to by in the UK

 

[MetalworkerMike]

Interestingly enough, I was just ordering a new blower for a machine, from Dayton, and these blowers (much smaller than 2.2kw) are only available in two flavours... Shaded pole and PSC.
Just thought I'd toss that in.

Mike

 

[jraef]

Yep, certain types of blowers and pumps, loads that don't need much starting torque, represent most of the applications where PSC motors can be used. Shaded Pole are good for just fans and blowers for the most part. The big ceiling mounted paddle fans are shaded pole, as are most muffin fans and aquarium/fountain pumps. Little stuff mostly.

 

[davidbeach]

Shaded pole motors pretty much have to be used for fans, and the motor has to be in the air stream of the driven fan. The shaded pole motor is woefully inefficient and all that heat has to be dispelled or the motor would fry itself.

 

[itsmoked]

By far the greatest use for single phase VFDs is for fans on PSC motors for refrigeration condenser fans and in rarer cases evaporator fans.

In refrigeration you need to keep the suction pressure up or the system will stop doing useful work, amongst other things. This means slowing down the condenser fans based on pressure.

Evaporator fans are generally slowed only in cooling,(as apposed to refrigerating or freezing), applications like wine cellars, as you need to keep the corks from drying out but you want to cool the environment so air velocity and relative humidity come in for speed control.

Keith Cress
Flamin Systems, Inc.-

http://www.flaminsystems.com

 

[Javier72]

Yes, I have used this control and it really works without any problem. Sorry because the problem in this case is the motor power (very high for the control) but the control is really for Single phase (little) motors, as yo can see in the page.

You are talking about three phase motors transformed to single phase with switches, but as you Know, little motors are not always done like you say.

 

[Kiljoy]

To tell you the truth, we have never actually had an application for a single phase drive...
I pulled out the 'ol textbook from my college motors class and it touched on some speed control methods for single phase motors. It mentioned varying the frequency, but didn't tell you which motors it would work on.

 

[themroc]

Finally I just want to thank all for their contribution.
It seams to be a quiet complicated topic. In the end we solved it by using an additional valve assembly and we bleeded some air.
But I am still curious to know how domestic single phase motors are controlled, I stated the vacuum cleaner. Or are this in fact three phase motors running on a single phase.

 

[OperaHouse]

Vacuum cleaners are almost always AC-DC brushed motors. I have a leaf blower, the lower speed is accomplished by inserting a diode in the line making the average voltage half.

 

[jraef]

Most small household appliances and hand held power tools use AC/DC universal motors because they are simple to control speed and usually have relatively short duty cycles. They are limited in size however, so for new larger appliances such as washing machines, they have indeed gone to 3 phase motors with VFDs that convert the 1 phase source to 3 phase. That is what is behind most of the newest energy efficient washers and dryers now. That's also why they are more expensive I'd imagine.

 

[MikeHalloran]

Gotta love them energy efficient appliances.

I've been looking for more than a year for a replacement motor for my a/c air handler that doesn't cost more than a whole new air handler.

It was great, while it worked.



Mike Halloran
Pembroke Pines, FL, USA

 

[jraef]

That's disturbing, but I'm affraid it's the wave of the future.

 

[itsmoked]

Been that way for a while now.

I bought a 3-1/2HP trash pump with a polycarbonate pump $229. I hooked it up with a garden hose and an output valve. I wanted to charge the pump and turned on the garden hose. The pump body promptly split open. DOH! Live and learn. I call them for a replacement pump housing. $199!!! That was about a decade ago.

Keith Cress
Flamin Systems, Inc.-

http://www.flaminsystems.com

 

[ozmosis]

In a previous life I was about to test this from Invertek:

http://www.invertek.co.uk/product_optidrive_e21.aspx

but never actually got round to it. I have spoken to a few people about it and it does seem to work effectively if not a little pricey compared to the relative cost of the motor and 'expectation' of drive cost.

 

[jraef]

 

[Skogsgurra]

That horse aint dead till the fat lady sings. PLS for your contribution, Jeff.

Gunnar Englund

http://www.gke.org

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100 % recycled posting: Electrons, ideas, finger-tips have been used over and over again...