Wiring a desk electric fan.
 

I have a desk electric fan that I wish to rewire. The wires from the motor and the switch which is a later Made in Taiwan addition have been cut. I enclose image of motor.

I fully appreciate that this is primarily a radio technology forum, but if anyone is able to afford me any assistance on this matter, I would be grateful and will forward further details and images. Thank you.

Re: Wiring a desk electric fan.
 

Cool! I think your post is welcome in this category. :) What make / model is the fan? Any idea of year and / or the original intended power supply? (I'm aware that quite a few different mains supplies existed in the UK at one time.)

I believe I've read that forum member Ed Denning(?) rewinds transformers...perhaps he can offer assistance?

One of my many projects-in-waiting is a 32 volt DC fan from the US...I've yet to find out if its windings are still good or if someone plugged the thing into 117 volt AC mains and fried it. Either way, I'd be interested to hear how you get on with your project! :)

Re: Wiring a desk electric fan.
 

If you have a multimeter, it may be helpful to measure the DC resistance between each of the wires (after labelling any that aren't otherwise distinguishable from each other). Although this won't necessarily indicate the impedances at 50/60 c/s (Hz), it may at least give some clue as to how it is wired.

Re: Wiring a desk electric fan.
 

Firstly, thank yu'all for taking the time to reply. The weight of the fan(8 plus kilos) and the components tend to indicate it might date to the 1930's/ 1940's, certainly the oscillator gearing looks to emanate from that period. The natural patina on the guard and blades also indicate that sort of age. There are many similar style Thai reproduction models on the internet, although with various subtle differences. I'm fairly sure this isn't one of the aforementioned, because of the quality,components and perhaps most poignantly, the weight. Mine is twice as heavy. I enclose further images.

Of the 5 wires, 4 are black and one is brown with a white stripe. Each wire is 0.5 mm diam. I have now soldered the wires and made a harness to a 5 core cord. The closest I could get was a cord with 0.75 mm wiring. Obviously, all the colouring of the wiring is different and I have attached the brown wire to the brown/white striped wire from the winding. The 3 speed switch has obviously been replaced with one of the Made in Taiwan variety. I will need to replace this with one that is more in period. There are traces of wire and solder on the 3 pins dictating the speed, there are also tracings of wire/solder on another of the pins. I do have a volt meter, but my knowledge of electrical matters is extremely limited, I restore antique clocks, vintage wristwatches et al.

There aren't any identification tags on the fan, although there may have been one on the bottom cover which is missing. The logo at the centre of the guard appears to resemble that of General Electric.

Re: Wiring a desk electric fan.
 

The modern switch which has been cut off - is an on/off, or some kind of speed selector? If someone has chopped it off as aesthetically unappealing without noting which wire went where, perhaps someone has shot themselves in the foot :) It might be worth inspecting the switch for remnants of wires attached, and using a multimeter on ohms range to work out what connects to what as the switch positions are clicked through - as well as measuring the resistances through the windings as suggested above . I don't think this will turn out to be a question to which the answer is already known; rather, a little measurement and investigation will be required.

Re: Wiring a desk electric fan.
 

An easy test to get the relative resistance readings could be performed with a meter connected across the plug pins of a known working fan. Even a modern one would do for this as the internal arrangement is largely unchanged inside them.

Re: Wiring a desk electric fan.
 

When I acquired the fan circa 20 yrs. ago( it had come from a house clearance) there was no mains wiring and the wiring from the motor and the switch had been cut at both ends leaving just the 5 wires protruding from the winding and bits of wire/solder on the switch connectors. The switch acts as an on/off and has 3 speeds. The connectors on the 3 speeds are the ones with tracings of wire/solder. There is also another connector which has tracings of wire/solder, therefore 4 wires were attached to the switch, one of which may have been a mains wire and not necessarily from the winding.

I presume whoever originally owned this fan didn't have any more use for it and cut the wires because they didn't want anyone else using it, or did so for safety reasons without realising it might have some collectible value.

There is some movement on my meter if I touch the prongs between the wires which hopefully indicates the motor is okay. Would it help if I take the readings between each of the wires from the winding. The problem with this being, the readings tend to fluctuate. Would there be another part such as a capacitor missing from the base, or would the wiring have only consisted of a switch and mains lead connecting it up.

Re: Wiring a desk electric fan.
 

Following Dave's suggestion, why not stick a masking tape tag on each of the 5 wires, number them, and then measure the resistance from one to another. That's only 10 measurements I think. Also (and this is a guide, not a guarantee of safety) measure the resistance from each wire to the metal casing.

Re: Wiring a desk electric fan.
 

Indeed. For five terminals, the full test matrix has 25 squares. But 5 of them are referring to the same terminal and itself again; and of the remaining 20 squares, each pair (low number, high number) has an equivalent pair (high number, low number). So as long as there are no semiconductors involved, you can test every possibility on five terminals with just ten measurements: (1, 2), (1, 3), (1, 4), (1, 5), (2, 3), (2, 4), (2, 5), (3, 4), (3, 5) and (4, 5).

Once you have the resistance readings, it should be easy enough to work out the equivalent circuit. There most probably is a common neutral and the speed changes depending where you connect the live, but let's see the measurements anyway.

Re: Wiring a desk electric fan.
 

Measuring low ohms can be difficult, is it a digital, or moving-coil meter?

Do you get the same fluctuation with the probes shorted?
Make sure the probes themselves, and the connection at the meter end are clean and free of tarnish, you should see a stable reading of less than 1 ohm with the probes shorted.
Finally scrape the tarnish off the wires you intend to measure.

Re: Wiring a desk electric fan.
 

If the rotor has some magnetic remanence and is moved, then the resistance teadings will appear to fluctuate.

Re: Wiring a desk electric fan.
 

This genre/era of fans are rarer than they might be, probably due to their reputation for eating children's fingers. Doesn't mean it can't be mounted out of reach or used in a child free zone (is there such a thing!?) The only other thing i would recommend is a plug in RCD to increase your safety margin.....although having said that we haven't established what voltage it is designed for yet.. I wonder if a search would elicit an image of the missing base plate/data plate you refer to.

What a beast- photo 2 looks like the screw from SS Great Britain!

Dave

Re: Wiring a desk electric fan.
 

If you define "child" as under 18-year-old, then my house has nearly a thirty year pedigree as such a zone.

Re: Wiring a desk electric fan.
 

The colours of the wiring from the winding are 4 x black, 1 x brown/white Since I have soldered a 5 core cord to the winding wires, the colours are now blue, red, black, green and brown Does this mean that I have 10 combinations to measure for resistance. ie:-

black-brown, black-red. black-green, black-blue
blue-red, blue-green, blue-brown,
green-brown, green-red.
red-brown.

I apologise for long interruptions with replies, but my postings appear to have to go through moderation prior to posting

Re: Wiring a desk electric fan.
 

Yes! Measure between each of the possible pairs as you have listed, and it should be obvious how the windings are disposed.

You've got enough connections for four speeds, unless there's something unusual going on, but the resistance readings should show what.

Re: Wiring a desk electric fan.
 

Yes, that covers all combinations.

The results should show what the connectivity is. With five wires, it can't be a simple set of isolated windings.

Check from each wire to the frame as well- one might be for earthing (grounding) though more likely this would have been a separate connection, if it existed at all.

Edit: SNAP! ;D

Re: Wiring a desk electric fan.
 

Yes, that's the idea

Oops - distracted by my cornflakes, hence the x-post

Re: Wiring a desk electric fan.
 

I have taken a wiring diagram of a modern fan(image enclosed) I don't know whether or not this will be the same as the wirings from my fan. I am also experiencing a lot of fluctuation whilst taking readings between the wires.(image enclosed of my meter)

Re: Wiring a desk electric fan.
 

I've now managed to get some readings. although there are fluctuations. The actual colouring of the wires in my 5 core cord which I attached to the motor wirings is grey, blue, green, black, brown, as opposed to red, blue, green, brown, black.

Readings:-

Green- Blue 30,
Green-Black 22
Green to grey 22
Green -Brown no reading
Brown-Black no reading,
Brown- Grey, no reading
Brown-Blue, no reading.
Grey-Black 27
Grey-Blue 22.
Black-Blue 55

Interestingly, I attached the Brown wire there aren't any readings on to the Brown/White striped wire on the winding(the only wire which isn't Black.)

Re: Wiring a desk electric fan.
 

Mmm. These don't make great sense, as they stand! We might expect 3 windings in series, which would give us 4 connections - one at either end, and two in the middle at the joining points of 1 & 2, and 2 & 3. Then the largest reading might be that around the outside of all 3 (here, blue-black) and gey and green might be the tappings in between.

Here it might go Blue-grey-green-black. Those numbers don't quite add up though... Brown and white was apparently (says Mr Google) the colour for a start winding to which a capacitor might be attached, but it would be expected to join to the other windings internally - and it seems this is not the case. Hmmm!