Shaded pole foot controller?

Shaded pole motors are true synchronous machines; thus their speed is not controllable - it is locked to the frequency of the AC power mains. Give it up. You need a universal motor with a universal motor controller. AFAIK, about the smallest universal motor you might find is the type used in Dremel tools and etc. Next time, make sure you ask for a universal motor speed controller and a universal motor - there are no shaded pole motor speed controllers.

OR

A source for a fractional horsepower (1/15 or so) parallel shaft gearmotor, with a full speed output in the 50-60 rpm range, and a universal AC/DC motor?

I've currently got a shaded pole gearmotor (Rex Engineering

6142H47), and a universal controller (Linemaster 980-SC3) which the nice people with the yellow catalog assured me would work fine together--------- NOT.

Help!!

Bill

Really? NO shaded pole speed controllers?

Bill

I hate to get into what could be a big argument, but I think I have a shaded pole fan motor blowing air into my coal forge. (It certainly doesn't have any brushes). I use a variac to control its speed. One company I know of sells this same Dayton cnetrifugal blower motor with a simple light dimmer for the same use and we have several (5)of them connected that way in one blacksmith shop I work in. These "dimmers" have a knob, not a foot pedal, but the idea should be transferable. The caveat is that you don't have a lot of starting torque at low settings. Maybe that's what's giving you trouble?

Pete Stanaitis

---------------------------------

BillM wrote:

spaco fired this volley in news:Q8WdnSoK88OKrdHanZ2dnUVZ snipped-for-privacy@bright.net:

Shaded pole motors certainly can be speed-controlled, although the term "control" is used rather loosely, since they cannot easily be governed for any specific speed/load combination. Rather, one sets them to the "right" speed for the application, usually by observation.

When a shaded pole motor is under-powered for the load, it enters into a "slippage" domain -- basically "skipping steps" of the incoming frequency The motor consumes more power per unit load (drastically reducing efficiency) and tends to overheat unless the demands on it are small relative to the motor's semi-synchronous capacity.

Still, we have them all over the place. Most cheap ceiling fans are powered by shaded pole motors, and most have speed controls, often of the inexpensive thyristor type that makes the motors buzz objectionably.

When you think about it, if they couldn't slip under load they'd have to start instantanously at their operating speed (like a capacitor-start motor almost does), rather than slowly spooling up.

LLoyd

Bill sez:Really? NO shaded pole speed controllers?

Bill, I stand corrected ! I should have said there are no non-electronic shaded pole speed controllers. If you knew this before, why did you ask the question ? Your question was re. a speed controller for a 1/15th HP gear motor. Let us know if you find one.

Bob (always correctable) Swinney

Bill

shaded pole speed

question was re. a

But twice in one thread?

From the Bodine motor handbook...

************************* Changing Rotor Slip The changing of rotor slip is simpler, less costly and the most widely used technique for varying the speed of an AC induction motor. There are three types of nonsynchronous motors to which this method is best suited: shaded pole, permanent split capacitor and polyphase. * *

• There are several ways to change the power input to an induction motor, and thereby increase or decrease the amount of slip. Listed below are those which are most frequently used.

Series Resistance Method: A variable resistor can be used to vary voltage across the winding of an induction motor See Figs. 8-20a and b. Series resistance can be used with either shaded pole or PSC motors.

* * * ********************************

But there aren't many applications where speed regulation will be acceptable. A squirrel cage blower (constant load, relatively high inertia) is one case where this sort of speed control *may* work. As someone else mentioned, a forge blower can be controlled by a light dimmer - it works, but response is *very* sluggish.

Shaded-pole motors are not synchronous, Bob. They're induction motors with typical squirrel-cage armatures. The shaded pole is the device that produces the phase lag, in place of the capacitor or combinations of devices used in bigger induction motors.

As for controlling them without a frequency controller, sometimes they'll respond to reducing voltage, but that's a back-asswards way to control an induction motor and it can lead to unhappy results. I've gotten away with it on really small fan motors but the torque falls away quickly as you reduce speed, and they'll lose it completely when the slip angle gets too great.

-- Ed Huntress

Well now -- Ed has corrected me also. I stand by my statement that synchronous motors are not speed controllable. My error was in saying "true synchronous motors" and I admit that. Shaded pole motors are really induction motors -- I stand corrected, again. I erred in trying to help an obviously confused OP. Can I be forgiven for a minor "slip" of the induction tongue ?? At any rate, the OP will be hard pressed to find a speed controller for a 1/15th HP shaded pole, induction, gear motor.

Bob (sorry I tried) Swinney

Shaded-pole motors are not synchronous, Bob. They're induction motors with typical squirrel-cage armatures. The shaded pole is the device that produces the phase lag, in place of the capacitor or combinations of devices used in bigger induction motors.

As for controlling them without a frequency controller, sometimes they'll respond to reducing voltage, but that's a back-asswards way to control an induction motor and it can lead to unhappy results. I've gotten away with it on really small fan motors but the torque falls away quickly as you reduce speed, and they'll lose it completely when the slip angle gets too great.

-- Ed Huntress

Hi Bob! Yes, I knew there were speed controllers, both "step" and infinite, for shaded pole. However, all that I'm aware of are wall mount for fan motors etc.

I'm (was) in need of a foot controller---and they don't seem to exist. Linemaster is the big dog in foot switches---and they say no.

I got 4 shaded pole gearmotors and universal foot pedal speed controllers dropped on me, with the task of building 4 itty bitty tree turners for the purpose of wrapping grafts in the nursery. All was well until I plugged them together---it does not work!

Could probably do it with VFD's and control with foot rheostats, but it seems like a lot of time and money to roughly control the speed of a 1/15 HP motor.

SOOOO---Just ordered 4 Dayton 1LPZ5 62 RPM right angle Universal Motor gearmotors from Grainger. Found some dimensions on them, and am headed out to the shop to fab ANOTHER set of mount plates. Job security--I guess.

Thanks to all who replied--I always learn something new here, even when it's something I didn't want to hear.

Bill

Well, they are, with frequency control. That's elaborate and often expensive, and even that won't work well with many motors that weren't designed to be speed-controlled from the outset.

Of course. That's what NGs are for. Eventually we zero-in on it, often after some under-damping and over-damping. d8-)

Yeah, if I wanted to speed-control a small motor, I'd buy something made for the job. It isn't worth screwing around with a little motor like that, IMO.

-- Ed Huntress

Yeah ! Thanx, Ed for letting me wriggle off the credibility hook.

Well, they are, with frequency control. That's elaborate and often expensive, and even that won't work well with many motors that weren't designed to be speed-controlled from the outset.

Of course. That's what NGs are for. Eventually we zero-in on it, often after some under-damping and over-damping. d8-)

Yeah, if I wanted to speed-control a small motor, I'd buy something made for the job. It isn't worth screwing around with a little motor like that, IMO.

-- Ed Huntress

God no, we wouldn't want a debate on RCM! Besides, how often do we get to gang up on Bob Swinney?

Speed control by varying voltage or RMS current can work (after a fashion at least) on a shaded pole motor running a fan or blower because the load has a strong relationship between speed and torque: greater speed requires more torque.

If the load is light or variable and/or torque doesn't depend much on speed, better motor choices are DCPM, universal series-wound with tacho feedback (as in a treadmill), universal shunt-wound, or induction motor with VFD. For low-speed as in a tree-turner, another possiblity might be a slo-syn or stepper but they tend to be jerky, noisy and require a different sort of drive/control.

Just use a Zero-max.....

Do they make a controller for induction motors? I thought they were for DC servos and steppers.

-- Ed Huntress

Careful Don! If you rile up the group on that subject, I may try to turn them on to the old jug-o-worms re. the idler motor and load current being in series in rotary phase converters.

God no, we wouldn't want a debate on RCM! Besides, how often do we get to gang up on Bob Swinney?

Speed control by varying voltage or RMS current can work (after a fashion at least) on a shaded pole motor running a fan or blower because the load has a strong relationship between speed and torque: greater speed requires more torque.

If the load is light or variable and/or torque doesn't depend much on speed, better motor choices are DCPM, universal series-wound with tacho feedback (as in a treadmill), universal shunt-wound, or induction motor with VFD. For low-speed as in a tree-turner, another possiblity might be a slo-syn or stepper but they tend to be jerky, noisy and require a different sort of drive/control.

They make a manually adjustable speed reducer box. If I weren't already making mounts for the universal motor gearmotors, I would take a hard look at them----given the enviroment the zero-max might be a better solution. Smallest I see is 1/4 hp.

Bill

on to the old

phase converters.

Oboy. Nevermind.

I've taken the speed controller for a ceiling fan apart, and read the patents. What is being switched is a 150 VAC film capacitor in series with the shaded-pole induction motor. There are no semiconductors present.

In the Lutron Skylark SFSQ-LF controller I have, there are four speeds (including OFF):

High: zero ohms, capacitors are shorted and motor is connected to line.

Medium: 8.9 microfarad capacitor (with 100Kohm bleeder) in series.

Low: 4.7 microfarad capacitor (with 100Kohm bleeder).

Off: open circuit.

Joe Gwinn

Joe - did you happen to measure the current also? If so, I'd like a look at the result, if you could.

Hul

Joseph Gw> > > I hate to get into what could be a big argument, but I think I have a