The can of worms is back! (blower motor speed regulation)

LOL.

I have never made a talking video, but since I find Myfordboy's silent videos so annoying without vocals (although still highly educational and useful; not looking the gift horse in the mouth you know), I guess I will try it.
My monotone speaking tends to make people go comatose within seconds, and I am sure people will be hitting the fast forward or mute button on my videos.

And I certainly don't do the high energy sales talk thing; I am not trying to sell stuff and I don't monetize videos.

I watched this video, and I would probably be described as "low energy", or "no energy".
Well if the shoe fits........

Maybe I can spice it up and shout something like "How the Heck are YOU today !", but I don't think it would come across as sincere (and it wouldn't be).

I am like the guy at 0:48.
I have been in several high-stress situations at work where a client calls me up and he is in a desperate situation, his equipment is failing or has failed, his process is down, and if he can't get it going again quickly, the costs will be about 5M or more per day.
They rely on me to make things right, and I have been faced with 50 panicking people who are counting on me to remain calm, cool, collected, take over the situation, and instantly make the right decisions and direct people and materials.
I have saved a number of client's asses, but it was in a calm manner, and I was well aware that disaster was just one step away, and any mis-step would be career-ending. Sort of like Billy Joel's song "Pressure".

 

This is my life some days; I am sure we all experience this from time to time.
I feel a lot of pressure when the iron goes molten in the crucible, knowing that I have to lift it out, and hoping the crucible doesn't fail.
I sweat bullets before an iron melt.
Perhaps it will feel more routine as I do more of them.

 

You can do it Pat. It's just an open ended conversation with an invisible person. I'm sure you talk to yourself like the rest of us do when doing this stuff anyways. Just share it.
No one will poke fun at you I promise! When you have passion about a subject, it becomes infectious to others when you share it. I flight instructed for a few years and was scared shitless the first few lessons.... I soon found my groove and then I had more students than I had time for. Everyone wanted to work with me because of my easy going and fun approach to training. As long as I can remember, I was always happy to share my knowledge IF the other person was interested and most importantly, MOTIVATED! When you have to seek out someone's motivation to keep them progressing, it becomes a chore. I kicked those slackers as fast as I could.

No silent films! They went out a 100 years ago. The whys of how something is done is more important to me then your end results.

 

on motors. There are 3 types of motors commonly available to us. 2 of them work OK with voltage control

The two that work with voltage reduction are the universal motors that have brushes, the other is a shaded pole motor normally less then1/4 hp, the speed of the rest of the ac motors is based on the Frequency and slowing those motors is best handled by changing the frequency, when changing the frequency the voltage is also typically lowered as the impedance ( motor winding effective resistance) drops as the frequency goes down.

most motor controls require a load connected, digital voltmeters do not load a circuit, dimmers need a load to average out the voltage spikes created by the switching.

Art B

 

I'll play Art.... Microwave blower motor. What is it? 66% odds of being right. I've bet on less!

 

It may be easier to shoot the video, make some notes after and dub in a narration track later. That way you can make it the voice perfect and even leave any background sounds captured during filming. I have about one "Ummm" about every three words when I don't have a basic script beforehand. Anyway everyone's earlier videos sound a bit bad compared to their later efforts.

With regard to blower speed control, why not run the blower at full motor speed and just have a sliding ply or metal plate to block the blower exit pipe. It doesn't overload the blower as the impeller just stalls and runs faster as the load reduces. Some of the wood butchers on Youtube have such a blower gate setup for their sawdust extraction fans. Centrifugal blower output doesn't scale linearly with rpm either and relies on running at rated speed for best performance.

 

That's a fancy air gate. Who sells that? Nice and compact. I approve!

 

most microwave blower motors will be shaded pole motors and controllable with a dimmer, if they have a capacitor hooked to them (PSC) the are a normal AC motor although a fractional HP PSC motor will slow down because as the voltage goes down, the charge discharge time on the capacitor takes longer and effectivly provides a lower then 60 cycle frequency, they will run hotter and if you try to slow them down much more then 25% they will over heat.

the shaded pole is the copper bands or large copper wires that are on the rotor shell. They cause a shift in the magnetic field of the field winding. these motors have a lot of slip and lowering the voltage reduces the strength of the field and allows more slip. Most are wound so that even if the are stopped they wont burn up the windings, this protection is called Impedance Protected motors

Art B

 

Here you go: https://www.woodstockint.com/produc...essories/fittings-and-connections/blast-gates

 

Thanks for the motor lesson... Both of my microwave blowers have capacitors...