how to control speed of single phase motor
how to control speed of single phase motor
(OP)
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
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





RE: how to control speed of single phase motor
If you want to do this correctly, and effectively, you need to replace the motor with a three phase motor. It should not cost very much as three phase motors are simpler, and smaller, then the single phase motor you will be replacing.
Then pick up a VFD and you can then control the motor accurately, easily, and with only single phase power. You will also automatically have speed and power values available for your activities. VFDs that small are very inexpensive too.(Huge bang for the money!)
Keith Cress
Flamin Systems, Inc.- http://www.flaminsystems.com
RE: how to control speed of single phase motor
what means S.O.L?
Unfortuatelly I do not have the possibility of changing the motor.
How do vakuumcleaner vary their speed, are this 3 phase motors?
RE: how to control speed of single phase motor
Varying the speed of a single phase motor isn't that hard, it's just doing it _accurately_ that is very hard. You can run a single-phase motor of the 'furnace fan' variety through a cheap, household dimmer switch (the kind meant for lighting) and you will be able to vary the speed, but the speed will not be stable - any variance in load will vary the speed of the motor. If that's not a problem then your solution might be simple.
If a consistent speed is important (and for this kind of testing I would presume that it is) then you might be better off with a variable speed gearbox if a three phase motor is not feasible.
A variable speed gearbox will allow you to change the speed of your fan while keeping the set speed of the motor.
A new 3-phase motor and VFD would probably be cheaper than a variable speed gearbox.
Alternatives include a DC motor with a suitable controller, or if you need to do it on the cheap you could make your own 'gearbox' by just swapping chains and sprockets or belts and pulleys between the motor and fan. This assumes that you have access to cheap fabrication. One last alternative would be using the cheap dimmer switch but adding a speed pickup on the motor so that you can keep adjusting it until you get the RPM that you want, assuming that the load is non-varying.
Mike
RE: how to control speed of single phase motor
Converting to three phase and then using VFD seems to be an overkill.
RE: how to control speed of single phase motor
http://www.anaconsystems.com/text/ps.html
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RE: how to control speed of single phase motor
Small single phase fan motors that can be speed controlled are special purpose induction motors designed for high slip. It would be uncommon to find this kind of motor at 2.2 kW.
RE: how to control speed of single phase motor
There are "universal" motors such as itsmoked mentioned, also "Shaded Pole" motor designs that can be controlled via resistors or rheostats, but they are of limited use and about a 99% chance of not being used in your blower.
So if your motor is not PSC, your choices would be to swap it out with a PSC version (if that works out mechanically) and use one of those 1 phase VFDs, or swap it out with a 3 phase motor and use a more standard off-the-shelf VFD to convert your 1 phase source to 3 phase for the motor. That is a common practice now because most VFDs 3HP and under will accept 1 phase input without derating.
RE: how to control speed of single phase motor
Keith Cress
Flamin Systems, Inc.- http://www.flaminsystems.com
RE: how to control speed of single phase motor
RE: how to control speed of single phase motor
RE: how to control speed of single phase motor
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RE: how to control speed of single phase motor
Keith Cress
Flamin Systems, Inc.- http://www.flaminsystems.com
RE: how to control speed of single phase motor
These guys all have single phase drives:
AB Powerflex 4 & 40
Yaskawa CIMR-VU
WEG CFW08
RE: how to control speed of single phase motor
RE: how to control speed of single phase motor
Single phase motors are very different from 3Ph motors. They have switches in them!!!!!
Keith Cress
Flamin Systems, Inc.- http://www.flaminsystems.com
RE: how to control speed of single phase motor
Every time this subject comes up, someone jumps on this; it's probably the most common misconception out there. The vast majority of drive salesmen don't bother to explain their demo case to people (or don't understand it themselves) so they leave with the customers thinking they just demonstrated a drive for a 1 phase motor.
As Keith said, those demos are showing a 3 phase drive and motor, fed from a 1 phase source. You CANNOT use any drive made by Allen Bradley, Yaskawa or Weg on a 1 phase motor.
RE: how to control speed of single phase motor
RE: how to control speed of single phase motor
RE: how to control speed of single phase motor
There are only a small number of manufacturers who offer a 1 phase VFD for a 1 phase motor. Invertek out of the UK is by far the largest, and their drives are brand labeled by several other people in the US such as Bardac and Anacon (one of the ones shown in the links above posted by Andreb). There are 3 or 4 small manufacturers specializing in the HVAC industry for bathroom fans, but the applications are extremely limited because they can only be used on PSC and Shaded Pole motors, which are a small percentage of 1 phase motor applications to begin with.
Interestingly funny side note.
The other link put up by Andreb shows a Flygt VFD that says "for 1 phase motors". But if you go to Flygt's website there is no info available. That drive name (on the image) is registered to Bell and Gossett, Link a different division of ITT. They show the drive in their info, but CLEARLY state that the drive is ONLY for 3 phase motors! So even the marketing dept. of a manufacturer can't keep it straight!
RE: how to control speed of single phase motor
Just thought I'd toss that in.
Mike
RE: how to control speed of single phase motor
RE: how to control speed of single phase motor
RE: how to control speed of single phase motor
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
RE: how to control speed of single phase motor
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.
RE: how to control speed of single phase motor
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.
RE: how to control speed of single phase motor
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.
:)
RE: how to control speed of single phase motor
RE: how to control speed of single phase motor
RE: how to control speed of single phase motor
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
RE: how to control speed of single phase motor
RE: how to control speed of single phase motor
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
RE: how to control speed of single phase motor
RE: how to control speed of single phase motor
RE: how to control speed of single phase motor
Gunnar Englund
www.gke.org
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100 % recycled posting: Electrons, ideas, finger-tips have been used over and over again...