throttle an a/c pump?

striker85 · Apr 30, 2007

I have a 110v a/c mag drive pump. When I plug it in it goes full blast, no other options. I have it encased in foam and not touching any part of my case but I can still hear the thing humming away. Is there any way I can splice something in to the power cord or somewhere in order to throttle it down a little? I tried googling a/c motor controls but nothing really came up.

greenmaji · Apr 30, 2007

AC motor dimmer would fall under the same catigory as ceiling fan dimmer swich.
Something like this
http://www.farm-home.com/cgi-bin/miva?/mn/t9_main.pl

*a dimmer switch for lighting is NOT the same

Otter · May 1, 2007

greenmaji said:
*a dimmer switch for lighting is NOT the same

Very true. If you try to control an AC motor with a regular dimmer switch there's a good chance of starting a fire.

The link above didn't work when I clicked it, so here's another one:
http://www.controlres.com/nimbus.htm

res0r9lm · May 1, 2007

it depend on the amps. a dimmer switch rated for 1500w is good for 12 amps or one for 1000w is good for 8 amps. you would have to have a pretty large motor to draw that much power and should have it's own circuit if it did. I seriously doubt the pump draws much power.

Otter · May 2, 2007

The problem isn't the amperage through the dimmer, it's that an AC motor's speed is determined by its design and the frequency of the current. If there isn't enough voltage to keep it up to speed, the motor can get very hot.

striker85 · May 2, 2007

I believe this pump only draws 30~40 watts using 60hz 110v a/c current. I understand your point Otter. So, would putting it on a dimmer switch be an option as long as I don't drop the voltage too much?

Otter · May 2, 2007

No, that would just be asking for trouble. Have you heard of refrigerator motors "browning out" because of low voltage? That's exactly what will happen to your pump if you put a dimmer on it.

striker85 · May 2, 2007

So in other words, trying to throttle my pump just can't happen? Poo...

res0r9lm · May 2, 2007

you'll probably find out that the actual voltage from outlet is around 120v. You should be safe at 105v but no lower. the problem is electricity isn't the same voltage you have flucation.

speed bump · May 4, 2007

You would need a variac. However they are fairly expensive and some things don't like being undervolted to much. (my Ehiem 1250 was okay)

res0r9lm · May 4, 2007

seems to me a pull chain switch for a ceiling fan would work and you can get those at any hardware store for a few dollars.

Diggrr · May 4, 2007

@res0r9lm, that's just a three pole on/one pole off switch.
The three speed ones are simply turning on/off different coils in the motor to achieve the speed change.
That requires a motor that is wound with two or three sets of coils....one reason ceiling fans have 10" wide motors.

greenmaji had the correct answer. AC motors need an AC motor control to change their speed.

res0r9lm · May 5, 2007

Diggrr said:
@res0r9lm, that's just a three pole on/one pole off switch.
The three speed ones are simply turning on/off different coils in the motor to achieve the speed change.
That requires a motor that is wound with two or three sets of coils....one reason ceiling fans have 10" wide motors.

greenmaji had the correct answer. AC motors need an AC motor control to change their speed.

Ah thanks for clearing that up. I always wondered about all those wires. We have an older house and the ceiling fans that were in here weren't like that at all. there is no pull chain and motor is much smaller. fan is controlled with a switch on wall but it's not a normal switch it has a transformer and a fuse and a dial with off-1-2-3-4-5 settings

Diggrr · May 6, 2007

Well, never saw one like that before...guess we both learned something new today!
Must be a motor controller I haven't seen...yet.

QuietIce · May 6, 2007

With a transformer makes me wonder if it's VDC ...?

Otter · May 6, 2007

striker85 said:
So in other words, trying to throttle my pump just can't happen? Poo...

Not without an AC motor controller. These do tend to be expensive, but they're also usually intended for much more powerful motors. You might find something cheap on ebay, but if noise is the issue, it might make more sense to just get a DDC.

penquissciguy · May 7, 2007

Something like this would probably work. The price is right, too.

Ken

striker85 · May 9, 2007

I was looking at something like that. But the only thing is that it says it works with any brush type motor. My a/c pump works through induction, I'm pretty sure....that is to say I know for a fact it doesn't have brushes.

Otter · May 20, 2007

Yeah, that's for universal motors. It wouldn't work with an AC-only motor.

throttle an a/c pump?

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