How does the shaded pole motor work
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- Опубліковано 19 кві 2012
- An explanation of how shaded pole motors operate. Brushless induction motor basics. Troubleshoot of the motor is included. How to reverse this motor.
This video is part of the heating and cooling series of training videos made to accompany my websites: www.graycoolingman.com and www.grayfurnaceman.com to pass on what I have learned in many years of service and repair. If you have suggestions or comments they are welcome.
If you are a homeowner looking to repair your own appliance, understand that the voltages can be lethal, the fuels are highly flammable and high pressures are used. Know your limits. - Навчання та стиль
About 90° angle shift on start up through the shaded pole part of the motor to start rotation , Old record player turntable use to have them , also fan ovens , great video and well explained.
The primary winding magnetic field induces a voltage in the copper bar which becomes a magnet that is placed a few degrees offset of the primary winding. With an offset magnet, it will drag the rotor towards it and begin rotation. Hope this explains.
GFM
Thank you sir for showing small motors yet beneficial.
I needed to find out how to reverse my motor. You've given me that knowledge. Thank you!
you change the stator around to reverse it
My dad had to replace a fan on one of those pellet stove fireplaces and it had one of these on there. No need for the old one so he let me take it, cool to understand how it works, thanks!
All true. The shaded pole is simply an out of phase inductor used for starting. Thanks for the comment.
GFM
Simple stuff! But works great! Thanks for your explanation!
By increasing the length of the winding you increase the impedance (effective resistance to electrical flow). This reduces the amp draw thus reducing the power output the motor is capable of. So if I install a long winding then tap the center of the winding, the short winding will have less impedance therefore allowing more amp draw and more power output. Hope this explains well.
GFM
Thanks your my hero. I have look all over online for explanation on how these really work and your opinion on this is the best by far.
Awesome video, Thanks for sharing your knowledge. The reverse trick is amazing. Didn't know that.
2021 and I am using this video to help me with my studies. Greetings from west Australia
Glad I could help.
GFM
Great explanation!! Reading through my Nate book and this was the first type of motor they cover. Thank you so much!!!
Welcome
GFM
Excellent video. The info on reversing the motor was a surprise to me. I was always putting them back together the way they came apart.
Yes, the bushings are pretty cheap on these motors. The problem that I usually find with them, is that the lube on the bushings gets dirty and gooey. Once that is cleaned off, and new lube put back on, the motor is ready to go again.
+ke0nc
"Lubricated For Life". (or 1 year, whichever comes first)
Frequent cleaning and lubrication is what makes these motors last 50 years vs. 2 years.
+scdevon You sound cheap...uh...frugal, like me.
This was really great! Thank you a lot.
Thanks for this; you just relieved a headache from trying to work out how the hell these things work! I just fixed a small fan (almost identical to your first example) by re oiling and realigning the crappy bearings you mention ....temporarily ;-)
+matthew mountain Welcome
GFM
Excellent illustration, thanks !
Welcome
GFM
Shaded pole motors are like politicians. Shady, seem to run forever and extremely inefficient!
Such as Biden.
I'm a student studying this in my second year of the hvac program. This helped me understand it better!
Good stuff! Thanks!
Excellent explanation, just what i needed. Subscribed!
The second winding is not another speed its an aux winding around 30 volts to drive an alternative motor of other part of the circuit ,acts like an auto transformer.Use it in a Microwave and the other winding is used to drive a low voltage 30v turntable motor.
awesome video, lots of good info. I have one in my air hockey table that went out and can't find an exact replacement, i've found some close, but the mounting holes on new ones are just 2 on each side of the stator and about 3/8" apart. Would it hurt the motor if i drilled holes where i need them at the four corners of the stator? Also my stator "block" if you will is an inch thick. Does the thickness of that have any effect on the motor?
thanks for the help man :)
Appreciate your help.Tq.
Thanks for the explanation
Welcome
GFM
Thanks, I have lately been reading about all types of motors, do you suggest any books or websites? Im interested in all motors, universal, induction , brushed etc..particularly in how to wire brushed ones. Thanks!
Thanks a lot
public resource.org has some old vids on brushed motors. These are government vids from very long ago but are pretty good. I will be doing some work on motors in the grayfurnaceman and graycoolingman web sites in the future but have not gotten to it yet.
GFM
The amp draw is very close whether running or locked rotor. The windings overheat slowly mostly because there is no fan cooling. There are of course differences in design between different applications such as a motor not used as a fan would be designed with better heat transfer than a fan application. There is really no such thing as overload for shades pole motors.
GFM
Thanks! 👍
You got it!
GFM
The angle of the field bars in the rotor vs the magnetic stator field determine the rotating direction.
I have these exact motors
I think I'd pick one of these over something that requires a capacitor. I'm new to electricity and motors but it seems like something with a capacitor would just be more costly. That second motor gets the job done just by making a gap in the metal...if it's stupid but it works, it isn't stupid. And like you said, they don't use much power anyways.
Thanks for this! Wonder if you could use the stator as a tool magnetizer/demagnetizer when the rotor/bushing is finished.
+daikaiju20 You would have to run DC power thru it.
GFM
+grayfurnaceman Of course your right. Thanks for all you have up!!
So if you lock the rotor of a shaded pole motor, it draws the same current right? Does this mean that you cannot burn the motor winding by overload? nice tutorial :)
I have one disassembled too at home....Do you have any idea how speed switching works? I think it works by using 2 separated coils with different number of turns, affecting inductance and resistance thus producing different stator voltages, hence different torque.
duncpol seems about right
Cool!!
I'm doing a project where I'm using a small motor like this, what could I use to mount something to the motors shaft?
You could use a fan with a hub mount. All I can come up with.
GFM
how many turn in coil
Shaded Moles ! I LOVE IT HAHA
thanks dear , i have to ask something, what about noise of this motor ?
The motor noise is negligible, but the fan itself makes most of the noise.
GFM
most of the FASCO 3.3- 5 inch shaded pole motors aren't cheap to get than the small appliance shaded pole motors the round or C frame. as these motors are being replaced by PSC or ECM motors. as the early Vornado fans and Lakewood fans as many other fans from the late 1940s to up to 2000 used shaded pole motors as now they went to the cheaper PSC motors which don't last too long and catch fire as LASKO got hit hard on this on their box fans which forced LASKO and other fan manufacturers to put a fuse in the plug for safety. the smaller fans stll use a C frame shaded pole motor or the round skeletal 2 pole motor. as some of the larger C frame motors are being used for draft inducers for both furnaces and Water heaters. the drawback to shaded pole motors is their low starting torque and tend to draw more power than PSC motors when running. its common on these unit bearing refrigeration motors when the bearing fails they make noise and wind down and tries to get up to speed. as i have an older Vornado b-38 c-1 fan as im looking in replacing its motor which is shaded pole to a PSC motor as its driving a heavy metal deep pitched blade. and draws well over 2.4 amps when running. as im looking to see which PSC motor will work and fit the existing mount ring as the vintage vornado fans were made by the O.A.Sutton Corporation in Wichita Kansas from 1945-1959 when the O.A,Sutton Corp ceased production of the vornado fans and the company was aquired by Two Guys. and named it Vornado Inc. as today its Vornado Realty Trust as 1989 is when the Vornado fan was reintroduced and was kn own as Vornado Air Circulation Systems Inc till 2006 as today its known as Vornado Air LLC. the early of the circulators all used a shaded pole motor till in mid 2000 they switched to a PSC motor which was introduced on their 283 Heavy Duty shop fan. as today its known as the 293 Heavy Duty shop fan. As that fan is more preferred for job site as well as circulating air in a room. in all Vornado products are the best.
What lubrication is recommended for the bushing? Do some use just plain steel bushings? The ones in my cheapo fan don't look bronze.
The bushings won't be steel. They usually do not have oilers. You can add oil on the shaft that may help. If you can a zoom spout oiler, its the best oil. Motor oil will also work.
GFM
I used lithium soap grease hoping for a longer interval between lubrication. Would oil last longer? There is no felt to soak up lubrication.
Its not so much the oil, but the bearings are failing. New motor.
GFM
How should i plug in yj58-12A? To make it work? Deffenetly not on 220V. Could you give me some tips?
I've tried USB port and phone charger, didn't work
Well, I believe its just a 2 wire motor, and it appears to be 100 to 240 volt. Just plug it in.
GFM
I've been taking old room oscillating fans, small big and can't find a shaded pole motor in any of them. could I find one in an old microwave , refrigerator, dishwasher, shop vac, or clothes dryer? I need one and every time I open up an appliance I get something else.
***** Are you sure? They are by far the most common motor for the cheaper applications. They are in microwaves, refrigerator condenser and evaporator motors. Not in dishwashers. Shop vacs are brush motors. Dryers are PSC motors.
GFM
grayfurnaceman Thanks, I finally found one after operating on the 4th fan. That's not including the other items I tore apart. I kept telling my friends that all of the videos show these fans running a shaded pole motor. I thought I was losing my mind. Anyway it worked out great. Now I have a kick ass tool demagnetizer ready to mount on my workbench :)
Por favor
gostaria de ajuda para industrializar estes tipo de motor
What device installed on the core assembly on AC relays and starters to prevent hum and chatter is what? HELP
If it hums, replace it.
GFM
there is many kinds of Shaded pole motors the thick copper bars are called shading coils that other motor with the fan on it the thick copper shading coils are under the windings. as 3.3 incc, 4.4 inch and larger cost more than those mainly the FASCO, Century both of which are owned by Regal Beliot. the 3.3 inch shaded pole motors can have 2 to 4 poles, the 4.4 and larger can have 4 , 6, or more poles the more poles the lower the RPM will be as the larger Shaded pole motors draw alot of power. when i replace a motor in my vintage Vornado fan i prefer the PSC motor it draws less amps. as i think in the near future the larger Shaded pole motors will be phased out being replaced by either PSC or ECM. and the only motors that will be around would be the C frame and Skeletal shaded pole motors. which are used in fans, heaters, phonograph turntables, light duty pumps, as this US goverment gets more energy concious to find ways to use less energy.
Mantap
Q: How Does The Phase Shift Form?
A: One of the common characteristics of magnetism is the effect of resisting, or opposing change of current and magnetic field. It is used here as follows. The thick copper strap is a winding that is a *shorted turn*.
...
As the magnetic field from the main winding *increases* in the first quarter cycle of the AC, this induces a current (called eddy current) in that shorted turn. Remember that it is a *change* in magnetic field that induces a voltage in a conductor and therefore a current.
Because it is a heavy gauge wire it has a very low resistance and, therefore, a relatively high current (remember it is a shorted turn). This current must also have its own magnetic field. It turns out that this field *opposes* the one from the main winding and, therefore slows the buildup in that part (the shaded pole) of the stator.
...
As the main field *decreases* during the next quarter cycle, this induces a voltage & current in the heavy shorted turn in the opposite direction as before. This current has a magnetic field of its own as well and it is in the opposite direction as before, so it is in the direction to *ADD TO* the main field, thus delaying the collapse of the field in the shaded pole. This is a phase shift in the magnetic field of the shaded poles compared to the main pole. This can also be viewed as a delay in the shaded pole field giving a rotation of the overall field.
...
This phase shift induces a different current in parts of the rotor creating a torque. In a *VERY simplified* interpretation, you can consider the delay to be dragging the rotor in the direction from the main pole to the shaded pole, thus turning the rotor. [it's not quite that simple in an induction motor because there are voltages, and resulting currents, being induced in the rotor, but this is a good start] Ha ha... no pun intended. I saw this as I was proofreading!
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The opposition to change is the same thing that is called inductance; makes ignition coils work; and why a strong magnet will fall slowly inside a conducting pipe. The current induced by the changing magnetic field acts to resist the change in the magnetic field by creating an additional magnetic field that opposes the change by either subtracting from, or adding to the original field as needed (to try to prevent, or at least reduce or slow [delay] the change).
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The old mechanical speedometers used a rotating magnet inside a conducting cup. The current induced in the cup by the moving magnet, caused current in the cup and a magnetic field that resisted the change by "dragging the cup along" against a spring, and thus reducing the relative speed difference and moving the needle attached to the cup. The faster the magnet spun, more current was formed in the cup and more drag turned the cup more against the spring.
....
Hope that helps make the whole process a little clearer.
EDIT: Here's a *REAL* shorted turn for ya!
Liquid N2 and copper tube magnetic levitation
The induced current in the pipe produces a repelling field below the magnet and an attractive field above the magnet. The faster the magnet "falls" the stronger these fields become and when gravity is balanced, it reaches a fixed velocity as if there were no fields and no gravity. Since it is not accelerating downward it has no net force acting on it, so it travels at a constant speed.
It does. Thank you for a very complete explanation. The speedometer explanation was interesting as I have seen them work and that explains their operation very well.
GFM
grayfurnaceman Forgot to mention. It appears that the motor in the vid actually has two shaded poles, so there is a double effect. The larger one delays the main field some and the smaller one delays a little more because it is actually delaying the field from the first shaded pole. Pretty cool. I didn't know they did it with two.
i have 1 such motor i took out of a fan, but it has failed, anyone know the common causes of failure ?
Most of the shaded pole failures are related to bearings.
GFM
Any advice on how to repair a burnt motor like this one?
There is no effective repair here. Replace it.
GFM
If the windings are toasted you should disassemble the motor, remove the part of the laminations that's inside the coil from the main laminations stack and rewind the windings with the same diameter of wire and the same number of turns. Sometimes the coil formers are with very weird shape and are hard to rewind. Expect around 2300 turns per winding, that's a lot of work so really if you can find a replacement better take a new one.
Origoangelohrol322 thanks!!! how should I separate the laminations?
First remove the rotor with the bearings by unscrewing or unriveting.
Look at the sides of the winding formers where the inner lamination stack is contacting the outer lamination stack. Place the motor on two wooden blocks or whatever to support outer laminations stack so the coils are free in the air. Then find a convenient metal rod (a screwdriver or whatever) and a small hammer. Place the rod on the inner laminations stack and start to tab on the rod slightly and carefully. It should start to slip out. Then go to the other side and do the same thing. Continue in this manner to symmetrically get out the whole stack. Then try to figure out how to remove the coil formers. In some cases they are two sepasare and the task is simple, but if they are like the motor in this video (the one with the propeller) its very difficult to remove and to rewind, I broke one assembly like this recently its very werid construction and don't know how it's supposed to be disassembled and winded. Good luck!
But before disassembling the motor check if the windings are really burnt or melted, sometimes there is a thermal fuse on the top of the one winding which can be open. Find if there is one and shunt it. That can be the problem and the motor will be running again.
Just had to jump in here. You realize that these motors cost between $10 and 25 to replace and that winding replacement does not solve the most common problem with this type of motor. That is, of course, bearing failure. Just a thought.
GFM
Can the windings be replaced?
That depends on the design of the motor. Many can.
GFM
The whole motor is cheap to buy , normally its the Bush bearings which give up , these motors have little torque. and easily seize up which prevent the motor from turning on start up .
it would be a miracle motor if it was a 1/3 HP lol
+Ben Boudreau More like 1/100th HP LOL
@@scdevon 120V and 0.3 A equals 36 W. 1 horsepower means 746 W, so it's 0,48 HP (~1/20HP).
AC Induction motors WILL NOT COG If they have no phase offset.. Neither will AC induction motors with Run/Start capacitors to offset phase in windings.. WITH NO OFFSET, THERE IS NOTHING TO ROTATE THE ARMATURE.
thanks for never explaining how they work