It would be nice to have a picture of the NP on the motor itself.
Slow a Motor Down
- Thread starter Ronnie Barham
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It would be nice to have a picture of the NP on the motor itself.
kwired
Electron manager
- Location
- NE Nebraska
One easy way to rule out shaded pole is if there is a capacitor on it someplace, then it is not a shaded pole motor. If it is a oil filled capacitor it is likely a PSC motor, if it is not oil filled it is likely a capacitor - start motor.
lixinglong
Member
- Location
- Suzhou,Jiangsu,CHina
lixinglong
Member
- Location
- Suzhou,Jiangsu,CHina
A shaded-pole motor is basically a small squirrel-cage motor in which the auxiliary winding is composed of a copper ring or bar surrounding a portion of each pole.This auxiliary single-turn winding is called a shading coil. Currents induced in this coil by the magnetic field create a second electrical phase by delaying the phase of magnetic flux change for that pole (a shaded pole) enough to provide a 2-phase rotating magnetic field. The direction of rotation is from the unshaded side to the shaded (ring) side of the pole.
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Phil Corso
Senior Member
- Location
- Boca Raton, Fl, USA
My contention is that a 1 Hp shaded-pole induction motor is unlikely to be chosen to drive a hood-vent blower!
Regards, Phil
Regards, Phil
That looks like a 2 pole motor with a sync speed of 3600rpm typicaly used even in older record player motors. I'm not sure what the actual slip speed is. Don't they also have 4 pole shaded pole motors with a sync speed of 1800rpm?
kwired
Electron manager
- Location
- NE Nebraska
Search Grainger site for shaded pole motor and you will get about 30 pages of products ranging from 1/150 Hp to 1/4 Hp. I find it hard to believe that the OP has a 1 Hp version, as they just are not made much larger than 1/2 hp and even 1/2 hp is a rare find. A single phase motor that size that is speed controllable is usually PSC, or today you may find ECM motors, but those are much more expensive and likely would already have a speed control associated with the existing controller.
- Location
- San Francisco Bay Area, CA, USA
- Occupation
- Electrical Engineer
I think it's a valid point, but I also think it's possible that it is not 1HP, but 1/10th HP and says ".1HP" on the plate. I've seen that sort of thing happen a lot of small motors, I have had people INSIST that they had a 25HP 120V motor, when in fact is was .25HP...
If it is 1HP, it probably is more likely a PSC motor. In OEM blower motors, the cap is often buried in the back of the motor so it looks exactly like a Shaded Pole from the outside.
To the point that I made in a revious post, I would have been nice to see a picture of the NP on the motor which could have answered his question in a more timely fashion. But then all the fun would have been missed speculating.
- Location
- San Francisco Bay Area, CA, USA
- Occupation
- Electrical Engineer
Not to mention the exercise we get jumping to conclusions. :thumbsup:
kwired
Electron manager
- Location
- NE Nebraska
If OP tells us shaft size (even if estimated) there will likely be an obvious difference between .1 Hp and 1.0 Hp.
A general idea of the size of the fan/blower wheel may make it fairly obvious also.
I kind of have a feeling if this fan were .10 Hp the OP would not have the noise problem that started this thread, and the speed control he is questioning is definitely more than needed if it is only .10 Hp.
A general idea of the size of the fan/blower wheel may make it fairly obvious also.
I kind of have a feeling if this fan were .10 Hp the OP would not have the noise problem that started this thread, and the speed control he is questioning is definitely more than needed if it is only .10 Hp.
Did the OP post a picture of the NP on the motor which would resolve the speculation or did I miss it?
- Location
- San Francisco Bay Area, CA, USA
- Occupation
- Electrical Engineer
No, you didn't miss it. The OP is AWOL.
kwired
Electron manager
- Location
- NE Nebraska
No, but if we find out the motor only has a 3/16 inch shaft the likelihood of it being 1 hp is not very high.
Also if it has a 20 inch blower wheel, then the chance of it being successfully driven by a 1/10 hp motor is very unlikely, unless is turns really slow - then he would not have the noise issue though.
- Location
- San Francisco Bay Area, CA, USA
- Occupation
- Electrical Engineer
If you look at his posts again, he mentions it is for a couple who is now only cooking for two. That implies it is a residential cook top vent hood, 20" would be serious overkill, as would anything with a 1HP motor.
Then again, I have seen serious overkill in kitchen designs a lot lately. Just saw one with a walk-in freezer (and no, he is not a hunter or farmer, it was stocked with frozen pizzas and Costco meat from what I could see).
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kwired
Electron manager
- Location
- NE Nebraska
Anything requiring more than 1/4 HP motor is serious overkill for most dwelling unit cooking exhaust fan.
If indeed it is a 1 HP blower it is possibly trying to pull more air out than can come in - just allowing for make up air may help silence it some.
Sounds a little like one of those situations where "more power is better" and now they want to slow it down to cut down on noise - effectively making purchasing such a large unit a big waste of $$$.
Since we don't much let's start a pool on who has the best guess? The OP seems as if he/she simply poled a hornet's nest and ran away leaving us to guess as illustrated by the replies with no definitive answers.
It's almost as if he/she threw a grenade in our fox hole and ducked.
kwired
Electron manager
- Location
- NE Nebraska
Maybe, but then there would have been silence afterward except for the OP:happyyes:
I think OP pulled the pin on the grenade and then dropped it in his own foxhole.
- Location
- San Francisco Bay Area, CA, USA
- Occupation
- Electrical Engineer
"Honey, when the vent hood fan is running, I can't open the kitchen door!"
kwired
Electron manager
- Location
- NE Nebraska
It happens. I know of a Burger King that every time I have gone there you have to pull like hell to break the seal on the door, once it is open just a little bit it suddenly pulls easier and you can hear the air rushing in. Likely is no make up air in the design, or it is not working.
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