Swamp cooler fan speed control

Hi All,
Subject says it all. We have a 110vac, 1/3hp, 2-speed motor on the swamp.
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I would like to have variable speed. Are there any kinds of controllers that will do this without changing motors?
The Low speed is not low enough so I a looking to just use the High speed wire to the motor and spread control over the entire rpm range.
I am looking for a low cost thing. Kinda like a ceiling fan control that handles a 1/2hp motor. I say "1/2hp" for a little wiggle room if I have to change motors at some time in the future.
Possible?
Thanks
Reply to
Dave, I can't do that
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Probably not. It most likely has a start circuit that doesn't kick out until it reaches a certain RPM. That being said, you can close the louvers. It doesn't really affect the load from the squirrel cage if the air flow is reduced mechanically. It just spins in its own turbulent air.
Reply to
Bob La Londe
My understanding is that both PSC and shaded pole motors can be speed controlled to a degree by voltage control. I have a Comair Rotron Caravel fan, not as big as your motor, which is controlled through a ebm ziehl REE10 speed controller and it works very well giving a wide range of speed. It does make the fan buzz a bit at some settings so I get the impression the controller may be a phase angle controller but haven't put a scope on it to check and haven't checked what the fan is but it has no external capacitor so likely shaded pole.
Reply to
David Billington
Thanks guys,
@Bob: It doesn't have shutters, but I guess I could think about making some, although not really a practical option at this point.
@David: would something like this do? I can't find the REE10 etc this side of the pond. It says "constant voltage," so I a guessing not, but can't find anything so far that is variable voltage other than a $300 variable transformer.
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Reply to
Dave, I can't do that
I think that may be much the same thing as the REE10. I pulled the guts and it is all discrete components, resistors and caps, and the only semiconductors I can see are a bridge rectifier, a small diode like a 1N4148 size glass cased job, and BTA10 triac (SCR in the US IIRC), it also has a toroidal choke I guess for surge suppression. I looked up the Comair Rotron part details and it is one of these
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which it says is a PSC motor so the cap must be internal to the hub.
BTA10
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Reply to
David Billington
OK, thanks David, for six-bucks and change, I'll give it a try. What's the worst that could happen {VBG}
I'll signal back if the magic-smoke escaped or not later this week. Or maybe I will be buying that 1/2hp motor I pine for.
Reply to
Dave, I can't do that
I looked up swamp cooler motors and Grainger listed a number some being split phase where a winding is switched out when upto speed maybe like yours as no cap info was given on the rating plate so not suitable for speed control but they also listed PSC swamp cooler motors so maybe just a matter of choosing the right motor to suit voltage control.
Reply to
David Billington
If your motor has a switched start winding then you cannot run it a lower speed. The start winding is disconnected from the power when the motor reaches about 85% of the rated lowest speed. From the link provided it looks like the motor has a switched start winding. Turn off the motor while listening to it and if you hear a click and/or a whirring sound then that is the switching being heard. The motor will overheat rapidly if run too slow. For two reasons. First, the start winding is not made to be energized for more than the time it takes to start the motor. It heats up rapidly. Second, the motor will draw more current as the voltage drops in an attempt to get back up to speed. This extra current draw will cause the windings to run very hot until they let out the magic smoke. Eric
Reply to
etpm
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Notice the lack of cheap, simple ways. The real answer is to change the motor to a more easily controlled type.
The higher wire resistance that makes the start winding quickly overheat is there for good engineering reasons, not just to cut the cost or frustrate you.
Reply to
Jim Wilkins
Third reason: At reduced speed, there will also be reduced airflow over the windings which will contribute to overheating.
Reply to
rangerssuck

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