Yep you got it figured out it works just like you think it does.
Apparently the motor is a powerful magnet motor because if it was a brush type it would burn up.

When mine is open all afternoon their is no heat and when it shuts off the spring Will pull the arm back.

Like you I thought it would wreck my shutter because the one that I have is really strong.

I tried to hold it when it was running and that thing is powerful

I was in a similar fog when I was trying to tell my electrician how it was supposed to operate. Everything was fine, but it didn't seem right. Then at the end, I noticed the vertical bar in the center of the shutter seemed to be preventing the motor from opening fully, because it hit the bottom of the shutter frame. I foolishly cut the bar off about 1/2-inch. Then I found that the bar is DESIGNED to stop the motor arm from moving further, and it is the ONLY thing stopping it. This was confirmed by the shutter manufacturer the next day. I had to install jury-rig an aluminum stop in the frame to get the bar back on target. So the lesson I learned is not to fool with it if it's working!

Wow two replies and two direct bullseyes!!! Thanks folks, I had surfed 'til I nearly drowned on this subject and couldn't find a thing--I was THAT CLOSE to suffering the extreme humiliation of having to call the mfr about this! ;)

>Apparently the motor is a powerful magnet motor because if it was a brush type it would burn up.

Dunno what a "magnet motor" is gardenerwantabe but like you I tried to hold it with my hand and it clearly was Not about to yield to me!

>I found that the bar is DESIGNED to stop the motor arm

Good story gardnergal; something that confused me was in the motor instructions where it says "don't let the armature be stopped by the motor housing" which implied to me that it would grind itself up. Apparently that warning is just to assure the shutter opens fully!!?

Thanks again; you-all have reassured Me and no doubt future generations of hobby GH builders (who use google)! Maybe when I get a rainy day I will email the mfr and suggest a Sequence of Operation paragraph for their "installation instructions"!

"Dunno what a "magnet motor" is gardenerwantabe but like you I tried to hold it with my hand and it clearly was Not about to yield to me! "
All electric motors are "Magnet motors" there are many many many types of electric motors. It will take a whole book to explain.
In general, (I said, in gerneral) you have induction type and universal type. Induction type is AC powered single speed and rotates in one direction. Universal is bi-directional variable speed AC or DC powered. Universal type can have perminent magnets in its design.

When motors are stalled, they can burn out, unless there is a thermal reset switch. In the operation of shutters, somewhere there must be a limit switch and would also change the rotation of the motor.

dcarch

One more thing. Many motors of this type have internal gears, even the motor may not be powerful, you will not be able to turn it very well. You also damange the gears

dcarch

dcarch
The motor on the shutters has NO thermal switch.
It don't need one it is a magnetic motor like on a ceiling fan
If you hold a ceiling fan and turn it on you can hold it all day and when you let go it will start running.
It is easy to hold and it will not overheat
Their are no limit switches it runs until the shutter is fully open and then the power keeps pulling on it as long as the thermostat is calling for cooling.

When the current is cut off the return spring pulls the motor arm back and the shutter closes.
It is NOT a two way motor

Their is NO brushes in these type motors like what you are thinking about.

The only reason it has so much power is because of the gear reduction the arm just barley moves.

Thats possible also if the motor is specifically designed to work "stalled"
It is also possible that there are solinoids which works with circular motion actuation aor lineal motion.

Of course ceiling type of motor can also be reversible. that's why I said "in general"
There are so many types.

dcarch

>it is a magnetic motor like on a ceiling fan

Thanks for your clarifying post gardenerwantabe; this is all very clear to me now.

Someday I'll want to put a "killawatt" sensor on the shutter motor, to see what current it's pulling when it is stalled On. The label says 0.2amp i.e. only 24 watts!

My ceiling fan consumes 30 watts so the 24 watts sounds about right.
The motor itself has very little power but it must be geared 1000 to 1 and it is the gear reduction that gives it it's power.
Like Gardener gal learned it will just keep running if their is nothing to stop it.
I you remove the arm and turn the thermostat to make it run the shaft will go around and around because their is nothing to stop it.

Bathroom exhaust fan shutter typically is operated by the fan air force.

Some kitchen exhaust fan shutter is operated by a clutch link to the motor.

dcarch