Resonance in motors

[mbrownn]

Put this formula into an Excel spreadsheet, into cell E18:

=1/(2*3.1416*SQRT(E15*E16))

Then put into E15 the figure 0.0022 (this being 22 millihenries)
and 0.00046 into cell E16 (this being 460 uF), then we get
a frequency, in cell E18 of about 50Hz.

And so, if we have a motor of 22 millihenry field coils and place in
the circuit a cap of 460 microfarad, then we should have resonance.
for those in the UK or anywhere with 50hz mains.

It would be interesting to see how the motor responds as the value
of the cap is varied.

Interesting, by coincidence I found I was using a 470uF but at 200Hz, if the motor efficiency was 25% it sort of makes sense.

[mbrownn]

I think the rotating magnetic field is the answer, here is some text which
leads me to believe it. Still the iron core is limited to the lower frequencies I
think. But I don't see that as a problem. The only practical way I can see to
utilize a resonant motor is at a constant speed with constant load, I don't see
that as a problem either. The rotating field doesn't weigh anything but it can
drag the rotor around that's got to be efficient the way I see it.

The inventions, researches and writings of Nikola Tesla, with special reference to his work in polyphase currents and high potential lighting : Martin, Thomas Commerford, 1856-1924 : Free Download & Streaming : Internet Archive

This is from pages 24-25 of the book linked above. There is so much info on
motors in there I'm surprised people interested in motors have not read it. The
transformers and motors are basically the same thing except the motors have
an armature, then it can be a generator to, synchronous and torque motors
are described in different parts of the book.



Cheers

Thanks for the link, this seems to say what I am experiencing. The way Tesla writes only makes sense when you know what he is talking about

Constant speed and load does seem to be a requirement, using an induction motor connected to the grid as a generator could be the way to do this.

Probably the reason people don't take interest in these things is they don't understand it, like me hehe, I am learning slowly though.

When I posted some of the circuits I use I didn't realize that it was as I approached resonance that the COP went up. The closer we get to the resonant frequency of the coil by reducing the capacity of the cap, the higher the COP too. Problem is we will need one hell of a capacitor once we get up to those frequencies, maybe that is why it was a "home made" capacitor on the Lockridge device.

[Rl2003]

DynaMotor

This may or may not be relevant, but I thought it was interesting. We have
both voltage input and output voltage coming from a dc motor.
What is useful is the way the brushes are made. They are almost pointed, this
seems to allow for quicker on off times from one segment to the other
allowing for the high voltage out. With the inductors and caps the right LC
configuration maybe it could be fed back to itself at the proper freq.
Take a look at the 6 pic.s I put them in my bucket... I found this with other
smaller ones in a old warehouse under NY city..
Well, that is not all true. They where in an old storge place for the last 50 years.
It is not a working motor, the old wire is very fine and falling off the inductor
in small sections..I want to restore them at some point, but thought we may
learn some mechanical things from them anyway.

http://i1114.photobucket.com/albums/...0/DSC06520.jpg

Any thoughts, Mark

[nueview]

ok when you guys talk about the steel cores of motors it is interesting to me.
i made an induction heater some time ago and agree that the type of steel makes a big difference. but the most remarkable thing was cast iron at the start it seems like the totally wrong material as it is very magnetic susceptable but at speed 3600rpm it has almost no magnetic drag aqnd even less heating properties. it was my belief that the iron is not the problem it is the alloys elements that generate the most heating.

now as for resonance i would tend to agree speed could be a problem but i am willing to risk that to learn some of tesla's statements about using steady induced field magnetic cores and motor performance seem to go with what i have seen.

most of the induction motors i have run resonant seem to come in around 200-230 yf for 60 hz these are 3 and 5 hp motors.
the no load current for these is from .5-1.25 amps cycling about 9 amps in the tank circuit. just as a general rule 22 yF microfarad is worth 1 amp at 60 hz 120v input.

the term resonance is very loosely used here.
Martin

[Farmhand]

The bolded part of the quote is interesting. The way it's written isn't that
hard to understand for me, I just need to read everything about 47 times.
Then repeat.

The intensity of the poles being maintained constant, the action of the apparatus will be perfect, and the same
result will be secured as though the shifting were effected by
means of a commutator with an infinite number of bars.

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[mbrownn]

This may or may not be relevant, but I thought it was interesting. We have
both voltage input and output voltage coming from a dc motor.
What is useful is the way the brushes are made. They are almost pointed, this
seems to allow for quicker on off times from one segment to the other
allowing for the high voltage out. With the inductors and caps the right LC
configuration maybe it could be fed back to itself at the proper freq.
Take a look at the 6 pic.s I put them in my bucket... I found this with other
smaller ones in a old warehouse under NY city..
Well, that is not all true. They where in an old storge place for the last 50 years.
It is not a working motor, the old wire is very fine and falling off the inductor
in small sections..I want to restore them at some point, but thought we may
learn some mechanical things from them anyway.

http://i1114.photobucket.com/albums/...0/DSC06520.jpg

Any thoughts, Mark

These things are very interesting as you have a matched motor/generator all in one unit. I'm sure they could be made self running without modification. all we need to do is figure the parameters of the motor controller. Wish I had one

[mbrownn]

ok when you guys talk about the steel cores of motors it is interesting to me.
i made an induction heater some time ago and agree that the type of steel makes a big difference. but the most remarkable thing was cast iron at the start it seems like the totally wrong material as it is very magnetic susceptable but at speed 3600rpm it has almost no magnetic drag aqnd even less heating properties. it was my belief that the iron is not the problem it is the alloys elements that generate the most heating.

now as for resonance i would tend to agree speed could be a problem but i am willing to risk that to learn some of tesla's statements about using steady induced field magnetic cores and motor performance seem to go with what i have seen.

most of the induction motors i have run resonant seem to come in around 200-230 yf for 60 hz these are 3 and 5 hp motors.
the no load current for these is from .5-1.25 amps cycling about 9 amps in the tank circuit. just as a general rule 22 yF microfarad is worth 1 amp at 60 hz 120v input.

the term resonance is very loosely used here.
Martin

Hmm interesting, what type of motor was the iron in and what frequency?

[mbrownn]

The bolded part of the quote is interesting. The way it's written isn't that
hard to understand for me, I just need to read everything about 47 times.
Then repeat.






Uploaded with ImageShack.us

Exactly Im going to have to find time to study this book in detail. It usually takes me about half an hour to grasp what one page is saying but when Tesla writes there is more meaning than you can take in. At first his writing seems flowery but in truth every word has a meaning because you have to get inside his mind and visualize the concepts he is talking about.

It was said that he could visualize every detail of his ideas, to understand his books you have to do the same.

This quote is one of the easier ones

[nueview]

the cast iron was used as a magnetic rotor in an induction heater. but it failed horribly. here is the device.

Galloway Magnetic Induction Heater...Part 1/4 series - YouTube

i built this with my dad and got some help posting it from my brotherin law.

there are also allot of other effects that came into play with this device that make me realize how to stop the heating effect by making certain changes to the steel cores a sort of tuning of the plates.

Capacitance lowers Induction motor Amp draw by 80% - YouTube

the next is a capacitance box we made for testing it makes it easy to test motors for minimum current draw.

Induction motor capacitance TEST BOX Part 3 - YouTube

this is good information if you run induction generators.

Pt1 Induction Motor Generator - YouTube

the capacitance also determins the output power of this type of generator but what always gets me is there is no real starting field. such as magnets.
Martin

[wrtner]

Interesting, by coincidence I found I was using a 470uF but at 200Hz, if the motor efficiency was 25% it sort of makes sense.

I made a mistake. 22 millihenries is 0.022

[mbrownn]

Now it doesn't make sense. the truth is I had only two values rated at 400v on hand 330uF and 470uF.

[nueview]

this makes so much sense.
enjoy

IMGP5358 - YouTube

Martin

[wrtner]

Now it doesn't make sense. the truth is I had only two values rated at 400v on hand 330uF and 470uF.

Don't forget that you were not working with 50Hz. also, my formula
does not have any resistance in it. The circuit should be LRC, not LC.

Paul-R

[nueview]

ist pluse motor triligy!

IST PULSE MOTOR PART 1 - YouTube
IST PULSE MOTOR PART #2 - YouTube
IST PULSE MOTOR #3 NO BATTERY - YouTube

this came from the water wheel post if this didn't copy and paste right.
for all you pulse motor guys
Martin
it is the reference to the homopolar design that intregues me

[kenny_PPM]

question

Hi nueview

I sent you a private message with a question from your previous project referenced at overunity.com

Feel free to post the reply here also if you think it applies.

Ken