How to test (single-phase?) ac induction motor

[DartmoorHedgehog]

My Vortice extractor fan has stopped working and I'm trying to determine if the problem is the timer/controller circuit or the motor. I thought the easiest place to start would be to prove whether the motor works if I wire it up directly on the bench but I can't find any documentation about how I should connect it. It has five wires (red, blue, grey, black, white). I do know the black and white are for the high and low speed (it's a 2-speed motor). I can't find a spec sheet for the motor anywhere. It's one of these motors if that helps.

I don't really know much about ac induction motors so can anybody suggest how I should wire it up to test it? Or even just how to determine which wires are for what purpose with a multimeter. I've opened the case up and can't see any visible broken or burnt wire and the motor spins freely on its bearings.

 

[Taylortwocities]

You’ve started at the wrong place.
The likely culprit will be the timer board.
If the fan is 230v then simply dob 230v directly to the motor wires.
Then you’ll know if it’s the motor or not.

Quite honestly, you’re better
1. Checking that the right voltages are getting to the fan.
If ok then
2. Buy a new fan.

 

[ericmark]

Is it even a single phase motor, my freezer and washing machine both use three phase motors, there is no reason today to be limited to single phase, poly-phase is so easy with an inverter, so looking at a motor it is very hard to tell what you have, even the fan in old computers was poly-phase.

So one has to start with the controls, unlikely it is not single phase, but in the main easier to work it out from the controls than from the motor.

It does depend which model, but extract fans are not expensive, the link you give shows a capacitor, and I found working with capacitor start without knowing the wiring was near impossible. I have seen Flyte pumps burn out due to selecting the wrong winding for start and run, it worked but not for long. Look up capacitor start motor and you will find a diagram like this or this which are clearly very different, three phase is easy, it is single phase which takes some working out.

So likely new fan is best option.

 

[DartmoorHedgehog]

OK thanks for the replies folks.

@Taylortwocities "simply dob 230v to the motor wires" - yes but which wires? There are 5 of them. I agree it may well be the timer that's faulty but I've checked all the discrete components and they're all OK (there is one IC that I haven't tested), and power appears to be getting to the motor connections, so I thought "surely it's easy to prove the motor itself isn't dead" - but seemingly not so easy

@ericmark Thanks for those comments. I must admit I'd assumed it would be a single-phase motor because it's running off the domestic mains but I may be wrong. There is a large capacitor in the circuit between two of the motor wires (which does seem OK) which does make sense with the diagrams you linked to. I could just buy a whole new fan (it's a Vortice Lineo 100T V0 - looks to be around £80) but I just hate to scrap anything just because of what's probably a simple easily fixed failure somewhere. If I knew what the motor wiring was then at least I could do a better test of whether the timer circuit was working. As I said, there is mains voltage on three of the wires to the motor so I'm trying to work out what should happen to make the motor run, or what would make it fail to run. The bit of general information I've found suggests that if the starter windings aren't powered then the motor won't start on its own but should continue to run if spun manually - mine doesn't so I think there's more wrong than that.

I won't waste too much time on this as it is easy enough to buy a new fan unit, but it just annoys me that it's probably a really simple thing wrong with it - there's really not much there to fail.

 

[ericmark]

To try and get it running, good on you, but to spend money to get it running, likely not worth it.

 

[JohnW2]

Is it even a single phase motor, my freezer and washing machine both use three phase motors, there is no reason today to be limited to single phase, poly-phase is so easy with an inverter, so looking at a motor it is very hard to tell what you have ...

Do you really think it likely that an extractor fan would have a poly-phase motor and inverter?

 

[ericmark]

Do you really think it likely that an extractor fan would have a poly-phase motor and inverter?

unlikely it is not single phase

I did say unlikely, but I was surprised to find a PC fan to use poly-phase, but they did.

 

[JohnW2]

I did say unlikely, but I was surprised to find a PC fan to use poly-phase, but they did.

I'm not sure how far back in time you're talking, but I think that virtually all computer fans I've ever seen (all the way back to the 80s) have been 12 V DC.

 

[DetlefSchmitz]

I think that virtually all computer fans I've ever seen (all the way back to the 80s) have been 12 V DC.

I expect Eric was confused by the four wire interface usually used.
GND, 12V, PMW control signal and feedback sense output.

 

[ericmark]

The 12 volt fans I found in PC's were poly-phase devices, using an inverter built into the fan.

 

[JohnW2]

The 12 volt fans I found in PC's were poly-phase devices, using an inverter built into the fan.

What exactly is a "poly-phase" DC motor ??

 

[JohnW2]

I expect Eric was confused by the four wire interface usually used. GND, 12V, PMW control signal and feedback sense output.

Yes, that would make sense. As I've said, I've never seen a computer fan with an AC motor oof any sort, let alone a 'polyphase' one

 

[ericmark]

The inverter was built into the motor, so motor feed was DC, but the motor was a brushless AC motor.

 

[JohnW2]

The inverter was built into the motor, so motor feed was DC, but the motor was a brushless AC motor.

Are yiou sure? Are you talking about 'then' or now? Are you perhaps talking about very 'up-market' fans?

Today, standard 12V computer fans ae commonly well under £10, sometimes as low as £2.50, and I find it hard to believe that they can include an inverter for such a price. Furthermore, the only place for an inverter would be in the hub, which is a relatively tiny amount of space.

 

[Harry Bloomfield]

I'm not sure how far back in time you're talking, but I think that virtually all computer fans I've ever seen (all the way back to the 80s) have been 12 V DC.

Me too - 12v dc, and later ones variable speed, brushless units. Perhaps Eric was on about mainframe computers, but my memory of those was that they used 240v fans, switched via stats.