Ventilator Problem

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PaulR said:
Is it possible that when assembled the air is drawn over the motor to keep it cool?
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I don't think so. All the fans I used blow air out but never give part of it back to cool the inside. I just wish the manufacturer has provided a motor temperature sensor since it has digital design.
On the tower fans they show the room temperature but never what goes inside.
 
I think the windings might already have been damaged by the lack of energy transfer earlier.
You could try taking resistance measurements, and compare them agains similar windings in another motor, or you could have a go at rewinding yourself if you have an evening spare.
 
Channel Hopper said:
I think the windings might already have been damaged by the lack of energy transfer earlier.
You could try taking resistance measurements, and compare them agains similar windings in another motor, or you could have a go at rewinding yourself if you have an evening spare.
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I don't think the windings are damaged. I inspected them visually for any sign of discoloration and they all seem perfect to me.
The ventilator worked as normal till the end of last summer and this year I hardly switched it on for any length of time, certainly no more than few seconds when the shaft didn't turn.
To be honest, I don't have the time to mess about with this ventilator anymore and it was fun today to get it working again with the help of few drops of oil.
It is just a bad design of the motor by the manufacturer which I discovered today quite by chance as I never had it without the cover in the past.
The new ventilator spec mentions it is of DC design whatever that means, and after running all night it just feels cool, not even warm.
 
DC presumably means it's a Direct Current Motor, so there'll be a rectifying, smoothing and regulating circuit somewhere.
 
No idea. Heating is still related to the current flowing, regardless of whether it's AC or DC.
 
Looking at the ends of the motor cage, they look like they're ball bearings, rather than sleeve bearings, if they are, then applying some oil to what is presumably hardened grease has loosened it up, for now, I'd still want to pull that motor apart to see what's going on with its bearings, especially as it's getting toasty...

And as for the heat, that could be a few reasons, the bearings could still be partially seized (spinning, but binding and therefore generating heat), it could be a shorted winding in the field coil, or it could be the run capacitor is failing, the bearings could be cheap enough to replace, but fiddly, shorted windings means it'd be bin fodder, and a faulty run cap is an easy job to remove and replace, just depends on how far into it you'd want to go, but given you've already stated you're giving up, I guess not that far in... :)
 
PaulR said:
Is it possible that when assembled the air is drawn over the motor to keep it cool?
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Fan blades at the front drawing the air over the motor, therefore it would run much cooler. if the fan runs and the blades rotate easily i doubt it is faulty.
 
TJExcalibur said:
Fan blades at the front drawing the air over the motor, therefore it would run much cooler. if the fan runs and the blades rotate easily i doubt it is faulty.
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The only way to find out what is really happening inside is to attach a temperature sensor to the motor body and monitor the temperature.
 
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