The fact that they could run in either direction when powered was sometimes very evident in the older wall clocks, if the anti-reversing mechanism 'kicker' had failed, on turning on after a power-outage, then they would often be seen with the second hand rotating anti-'clockwise'.

 

What many fail to understand is that many of those motors will run either direction, randomly.

Yes. Very cheaply designed motors like microwave oven turntables which run in any direction as direction does not matter.

 

Yes. Very cheaply designed motors like microwave oven turntables which run in any direction as direction does not matter.

Mine runs in either direction, which alternates dir every time it is powered.
By design.

 

First, I don't think I'd buy from a company named "Chancs", or as I first read it "Chances".

CW/CCW(UNCONTROLLAB)

This is the hallmark of an AC motor.

Yep, worked fine driving my AC motor.

Yep, also worked fine driving my all my DC motors.

Don't fully understand this statement. Clarification is needed, at least for me it is.

I just finished replacing this synchronous motor in a portable ice maker.
The interesting thing is that in this application, the motor direction is reversible. There is some discussion (which is incorrect) on a physics forum on how they manage to reverse the direction of the motor with just two wires connected to 120VAC.

If you have an idea on how this works I would like to hear it. (I know how it works but I don't want to spoil it for you.)


View attachment 315519

OK, I'm just taking a wild guess here, but if the motor has driven all the way to a mechanical limit and limit switch; the next time the motor is powered, since it can't continue in that direction it is forced to reverse direction. Once it has gone all the way back it may be hitting another limit switch that won't allow it to continue in the wrong direction. But this is just a guess; and certainly not an authoritative answer.

 

OK, I'm just taking a wild guess here, but if the motor has driven all the way to a mechanical limit and limit switch; the next time the motor is powered, since it can't continue in that direction it is forced to reverse direction. Once it has gone all the way back it may be hitting another limit switch that won't allow it to continue in the wrong direction. But this is just a guess; and certainly not an authoritative answer.

Yes. That is the conclusion I reached. Spook also said that in post #18.

 

Even an induction motor with a start winding will run quite well in the opposite direction if it is spun up in the opposite direction.
Just consider: The reversible, non-split capacitor motor has only one winding powered after the start-switch opens. So the direction depends only on the phase during starting. So if the start winding is disconnected, and you give it a good spin before switching on the power, it can run in either direction. It just will not start turning on it's own from rest.
So it is not only the tiny synchronous motors, but evidently most induction motors with start switches but only one run winding.

 

The difference of course is that the synchronous clock motor does not rely on induction, and has either a P.M. style or a DC fed rotor.
It reminds my of a couple of 100HP compressors I worked on that had some old (antique) method of synchronism, they were standard style induction, but also had a rotor coil that exited the motor via two slip rings.
During run-up, they were standard induction, the signal generated in the slip ring coil was an AC signal that represented the slip frequency, which was monitored by the controller, , as soon as the slip was around 3-4cycles. DC voltage was injected back via the slip rings, and Voilà, the motor came up to synchronism.

 

The difference of course is that the synchronous clock motor does not relay on induction, and has either a P.M. style or a DC fed rotor.
It reminds my of a couple of 100HP compressors I worked on that had some old (antique) method of synchronism, they were standard style induction, but also had a rotor coil that exited the motor via two slip rings.
During run-up, they were standard induction, the signal generated in the slip ring coil was an AC signal that represented the slip frequency, which was monitored by the controller, , as soon as the slip was around 3-4cycles. DC voltage was injected back via the slip rings, and Voilà, the motor came up to synchronism.

Quite interesting indeed. And certainly antique motors.I recall working on turning the slip rings on some very old WORTHINGTON 400 HP centrifugal compressor drive motors many long years ago. I do not recall the voltage of those motors, But there were three slip rings, as I recall. Now I am wondering about what kind they were. When they were started it took many long seconds to spin up. They were in a building in New Orleans that was built during the Huey Long era. A really interesting place to work at the time.

 

First, I don't think I'd buy from a company named "Chancs", or as I first read it "Chances".
This is the hallmark of an AC motor.

Hear that. I noticed the same thing on my second repeat order.

Don't fully understand this statement. Clarification is needed, at least for me it is.

WHAT I meant is I took my pile of 12VDC motors and applied 12VAC to them and they turned "properly."

And yeah, they would turn randomly in either direction when powered on. Total non issue when spinning the color wheel in my snow man.

 

.I recall working on turning the slip rings on some very old WORTHINGTON 400 HP centrifugal compressor drive motors many long years ago. I do not recall the voltage of those motors, But there were three slip rings, as I recall. Now I am wondering about what kind they were. When they were started it took many long seconds to spin up. They were in a building in New Orleans that was built during the Huey Long era. A really interesting place to work at the time.

This case they were 3ph asynchronous motors, and only 2 slip rings needed.
If they had three, which was also common on wound rotor AC motors that used speed control with 3 slip rings , cranes etc, the operator had a speed control handle that varied the induced rotor current output and hence RPM, no longer seen with the advent of VFD etc.

 

This case they were 3ph asynchronous motors, and only 2 slip rings needed.
If they had three, which was also common on wound rotor AC motors that used speed control with 3 slip rings , cranes etc, the operator had a speed control handle that varied the induced rotor current output and hence RPM, no longer seen with the advent of VFD etc.

The compressor/motor packages were old before transistors were invented. They were antiques in 1967, already. This was a 400 HP rotary/turbine compressor for a freon 11 system. Actually, there were twoof them for the older portion of the building

 

The wound rotor AC induction motor has been around for a lot longer.
The ones I referred to had a large variable resistor bank, fed from the armature slip rings, the motor operator would control the RPM by means of a rotary crank handle, a method extensively used on cranes up until the '80's '90's

 

Hear that. I noticed the same thing on my second repeat order.

WHAT I meant is I took my pile of 12VDC motors and applied 12VAC to them and they turned "properly."

And yeah, they would turn randomly in either direction when powered on. Total non issue when spinning the color wheel in my snow man.

OK, I accept your observation. However, I don't see how a DC motor can be run on AC. EVERY DC motor I've messed with, those having a permanent magnet in them, if powered with AC they would just vibrate, that is spin one direction for 1/60th of a second, then the other direction for 1/60th of a second - and repeat. They would never "spin", not with a permanent magnet. If you have a motor with a field winding as well as the armature winding then what you have is a universal motor, one that CAN run on AC or DC.

I had a bicycle generator, one that rubs against the wheel when moving. The generated power ran a headlight. Just messign with it one day (probably around 10 years of age) I back fed it with 12VAC. The motor vibrated. Then I spun it in one direction and it continued to run in that direction. When I spun it in the opposite direction it continued to run in THAT direction. Either direction, the motor spun at the same RPM. And the generator had a permanent magnet in it.

At the start of your thread I got the impression you were rotating the snowman. OK, I mis-understood. But if you're looking to spin a color wheel, yes, I remember those things, THIS is something like what you're talking about - I assume! I'm not recommending this, just trying to be clear on what purpose you are chasing. This Christmas season I put up LED lights that were color changing. The colors could be controlled by a remote control, and you could select several options. THIS is the one's I'm talking about. You could easily set these up to change colors in MANY ways. Far more than what you get from a color wheel. They fade from color to color, they mix and match colors, the rate of change can be varied, the patterns they change can be controlled.

Again, I'm not recommending you change anything about your project. Just sharing some observations and methods I've used in the past.

 

Revisiting the entire post. In the opening you said you were using a motor with this spec in it. I thought that to be a little on the under powered size.
Torque:≤0.5kg*cm
500 grams per square centimeter. Perhaps you're trying to move too much mass for the little motor ? ? ?
Also, that's "equal to or less than 500g*cm. Basically they're saying it can work up to that torque. But the startup torque might be more than the little motor can muster. Again, I don't know. And I'm proud to admit when I don't know something. It's better to fake ignorance than to fake intelligence and look like an ignoramus.

 

They would never "spin", not with a permanent magnet.

Of course there is the PM armature of a AC synchronous motor, the BLDC versions can be also ran on 3ph AC, as the BLDC and the 3ph synchronous are identical in structure and can be driven either way.

 

Of course there is the PM armature of a AC synchronous motor, the BLDC versions can be also ran on 3ph AC, as the BLDC and the 3ph synchronous are identical in structure and can be driven either way.

I'm sure there are exceptions. After all, I'm not the last word on all knowledge.

 

I have converted AC PM servo motors over to BLDC using an encoder that had commutation tracks on them.
Reason, the AC type had proprietary commutation encoder.

 

The color wheel to be rotated is very light, Not even an ounce, unless it is a heavy-duty version, and it is close to balanced so not much torque at all required. I think those are called "shaded pole variable reluctance motors.

 

To clear up some points...

I was attempting to replace a motor with a similar motor for the same purpose: to spin a very light colored disk. This disk is maybe 2 inches in diameter and weights less than an ounce. Basically first approximation is it is not a load at all. The image in my first post is the same size of the motor I need, spec'd to be 12VDC instead of the 12VAC I had been running up until my transformed died.

When I test a motor I don't even put the disk on it, just observe if the shaft rotates.

After purchasing a 12VAC power brick I ran the 12VAC motor successfully. I bundled up all the snowman parts and reassembled it. I've been running it for 2 days now as a bench burn-in, mostly to monitor the transformer's temperature, which is running acceptably, only slightly warm.

With the 12VAC source on hand I tried powering the "12VDC" motors with such. And they all worked with 12VAC. Either a mismark motor (directly on the motor body!) or some other shenanigans afoot.

 

OK, and the really good news is that you got a motor that does what you need at a reasonable price. And we all learned an interesting lesson which is that not all descriptions are completely accurate.