Three speed fan

I'm guessing: Do these work by having a two pole and four pole
arrangement? Switch in the two pole and get 3600- rpm, switch to four
pole and get 1800- rpm, switch in both for six poles and get 1200- rpm.
The geometry migh be somewhat screwed up in 4- and 6- pole
configuration but those are working at pretty low power.
I ask because my neighbour has one of these that only works on high
speed. I suspect the switch but before we commit surgery on it, I'd
like to understand how the thing is suposed to work. TIA
Ted
Reply to
Ted Edwards
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I'm not sure about the one which you have (a window fan perhaps?), but the multi-speed motors driving furnace squirrel cage blowers appear to be slip limited. They are cap run motors, and the taps simply select how much torque it can produce before it starts to slip. More torque means higher speed. But certainly not the range that 1200-3600 RPM would cover.
The switch (if it is as I think) will probably be simply a single pole multi-throw. Going from eix to four to two poles would require a rather elaborate switch, I think, even if the windings were capable of supporting all of those configurations.
Enjoy, DoN.
Reply to
DoN. Nichols

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