Generator coil output - Sorry if it's a stupid question
Generator coil output - Sorry if it's a stupid question
(OP)
Hi, I'm new here and I apologize up front if my terminology is incorrect. I've been a Civil Engineer for over 30 years, but am very far from an expert in electrical. Sorry if this is an elementary school level question for you guys!!!!
I am hoping someone here can either give me a hand or point me in the right direction.
I have a proposed electric coil design and was wondering if I am doing my power potential calculations correctly.
My "coil" at this point will be wound on an 2.5" long by 1/2" wide by 2" high iron or ferromagnetic core or spindle. I am looking at about 70 meters of AWG#20 magnet wire for the windings.
If I pass a neodymium magnet, Grade 42, gauss 13,200, 3" long, 1/2" wide and 1/4" thick directly under it, at a velocity of 2 m/s and 90 degrees to the long side of the coil I would like to be able to verify what amount of voltage I can get out of it. And then, based on the proposed circuit resistance, what power and current I can expect.
I've found and used the following HyperPhysics page to get an approximation. I will be supplying approximately 300 pounds of force to push the magnet past the coil.
My best guess, using the formulas from the above web page, is that I can get 730 Volts. And applying 200 ohms of resistance to the circuit will lower the push force required down to 300 lbs. This gives a current of 3.65 amps and a power output of 2674 watts.
I realize the calculations are only theoretical and there are probably many other variables that come into play, but if any of you could help me verify the numbers, or point me in the right direction, I would really appreciate it.
Thanks much in advance for any help you can offer.
I am hoping someone here can either give me a hand or point me in the right direction.
I have a proposed electric coil design and was wondering if I am doing my power potential calculations correctly.
My "coil" at this point will be wound on an 2.5" long by 1/2" wide by 2" high iron or ferromagnetic core or spindle. I am looking at about 70 meters of AWG#20 magnet wire for the windings.
If I pass a neodymium magnet, Grade 42, gauss 13,200, 3" long, 1/2" wide and 1/4" thick directly under it, at a velocity of 2 m/s and 90 degrees to the long side of the coil I would like to be able to verify what amount of voltage I can get out of it. And then, based on the proposed circuit resistance, what power and current I can expect.
I've found and used the following HyperPhysics page to get an approximation. I will be supplying approximately 300 pounds of force to push the magnet past the coil.
My best guess, using the formulas from the above web page, is that I can get 730 Volts. And applying 200 ohms of resistance to the circuit will lower the push force required down to 300 lbs. This gives a current of 3.65 amps and a power output of 2674 watts.
I realize the calculations are only theoretical and there are probably many other variables that come into play, but if any of you could help me verify the numbers, or point me in the right direction, I would really appreciate it.
Thanks much in advance for any help you can offer.





RE: Generator coil output - Sorry if it's a stupid question
RE: Generator coil output - Sorry if it's a stupid question
CODE
Length in axial direction Length 2.5000 INCHES 2.5
Width Width 0.5000 INCHES 0.5
Height Height 2.0 INCHES 2
Perimeter around W and H Perimeter 5.0 INCHES =2*(Height+Width)
Fractional Increase in mean perimeter due to coiling X 1.2 unitless 1.2
Expanded permiter ExpandedPerim 6.0000 INCHES =X*Perimeter
Number of turns Turns 5.00E+02 unitless 500
Total length of conductor Length 3.00E+03 INCHES =Turns*ExpandedPerim
Diameter of conductor Dconductor 3.40E-02 inches =0.034
Areas based on conductors Aconductor 9.08E-04 inch^2 =PI()*Dconductor^2/4
Total area of all condutors Atotal 4.54E-01 inch^2 =Aconductor*Turns
area calculated from X Acalc 4.00E-01 inch^2 =Width*Height*2*(X-1)
velocity Velocity 2.00E+00 m/sec 2
Rate of change of area wrt time dAdt 1.00E-01 m^2/sec =Velocity*Height/39.97
Flux density B_ 1.34E+00 T =13400*0.0001
Voltage V 6.71E+01 volts =B_*dAdt*Turns
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(2B)+(2B)' ?
RE: Generator coil output - Sorry if it's a stupid question
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(2B)+(2B)' ?
RE: Generator coil output - Sorry if it's a stupid question
RE: Generator coil output - Sorry if it's a stupid question
Right now I have it as 60 turns per layer and a total of 12 layers.
RE: Generator coil output - Sorry if it's a stupid question
RE: Generator coil output - Sorry if it's a stupid question
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(2B)+(2B)' ?
RE: Generator coil output - Sorry if it's a stupid question
Also, I'll mention that MacGyverS2000 is a valued regular and just excercizing his perogative to check up on your motives (we have seen plenty of students).
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(2B)+(2B)' ?
RE: Generator coil output - Sorry if it's a stupid question
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(2B)+(2B)' ?
RE: Generator coil output - Sorry if it's a stupid question
And I apologize for sounding off. It's been a long rough year.
Thanks so much for your help.
RE: Generator coil output - Sorry if it's a stupid question
If the length of the iron portion of a magnetic circuit is doubled the flux density resulting from the same magnetizing force is halved.
Keep your iron and magnet path as short as possible.
If part of the iron path is replaced by an air gap, the ratio may be over 10,000 to 1. Air gaps are bad. Air gaps are kept as short as possible.
That is the main reason that horseshoe magnets are made in a horseshoe shape.
Bill
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"Why not the best?"
Jimmy Carter
RE: Generator coil output - Sorry if it's a stupid question
If the output exceeds the input, then either a Nobel prize awaits, or perhaps there's an error in the assumptions.
RE: Generator coil output - Sorry if it's a stupid question
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(2B)+(2B)' ?
RE: Generator coil output - Sorry if it's a stupid question
h
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RE: Generator coil output - Sorry if it's a stupid question
Now that we've established you're not a student, I'm curious as to the project's purpose... always interested in seeing what other fields are doing and what for.
Dan - Owner

http://www.Hi-TecDesigns.com
RE: Generator coil output - Sorry if it's a stupid question
Would any of these things improve it in any way. Thanks in advance.
RE: Generator coil output - Sorry if it's a stupid question
Imagine a ring 1 inch thick and 6 inches in diameter with a 4 inch hole in it.
For a given magnetizing force, increasing the mean diameter will decrease the total flux.
For a given magnetizing force, increasing the cross sectional area will increase the total flux.
Now imagine a slot slightly greater than 1/4 inch cut across the ring. You may pass your magnet through this slot. There must be a small air gap to allow the magnet to pass, however one inch of air gap may be equivalent to about 10,000 inches of iron. (Check the magnetic property curve of the iron for an exact figure at the working flux density.)
To refine this a little further, Cut out a circular part of the ring that may be rotated in the ring. Mount the magnet in the center of this part and then rotate it in the hole from which it was cut.
The voltage will be proportional to speed of movement of the magnet or the speed of rotation.
Early magnetos had a mechanism that would stop the movement of the magnet and compress a spring. The spring would release and the magnet would rapidly pass the core/coil for a good spark. This gave a good spark when hand cranking an engine to start it. It had the added advantage of retarding the spark to avoid backfiring. Once the engine started centrifugal force would disengage the spring action mechanism.
oral:
The speed of the magnet past the core/coil is important.
The speed of the magnet does not have to be constant through-out its travel.
Bill
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"Why not the best?"
Jimmy Carter
RE: Generator coil output - Sorry if it's a stupid question
Playing with some ideas to see if anything comes of it, but I've got so much to learn and am still stumbling my way along.
RE: Generator coil output - Sorry if it's a stupid question
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RE: Generator coil output - Sorry if it's a stupid question
What you are describing sounds like a solenoid. Is that right?
I know a toroid is one of the most efficient shapes for controlling flux density, but I thought one of the important points for electricity generation was to have the magnet poles pass at 90 degrees to the coil windings. If the magnet were to be passed through the core/windings as you describe, how would you orient the magnet poles in relation to the wire? Maybe I'm not visualizing it correctly.
RE: Generator coil output - Sorry if it's a stupid question
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(2B)+(2B)' ?
RE: Generator coil output - Sorry if it's a stupid question
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RE: Generator coil output - Sorry if it's a stupid question
Pete, imagine the cutout circle to have a 1/4" slot cut midway across it and the magnet (i/4" thick) placed in this slot. No iron bridging across the ends of the magnet but of course some leakage flux.
We have a ring that is 1" across. Not the diameter but the external radius minus the internal radius. We have cut out of this ring a 1" circular piece and inserted the magnet into this piece. We have replaced this piece and are now rotating it. When the magnet is at right angles to the ring there will be maximum flux in the ring. 180 degrees later the flux will be maximum but in the opposite polarity. A wire coil wound around the ring (the wire passes through the hole in the center of the ring on each turn) will have a voltage induced in it by the varying magnetic flux in the ring. The ring may be replaced by a rectangular shaped core.
Bill
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"Why not the best?"
Jimmy Carter
RE: Generator coil output - Sorry if it's a stupid question
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(2B)+(2B)' ?
RE: Generator coil output - Sorry if it's a stupid question
I know that increasing the velocity will increase voltage, but is it proportional or exponential?
When you talk about cross sectional area, are we discussing only total winding cross section or is it core cross section, or both?
Thanks again
Jim
RE: Generator coil output - Sorry if it's a stupid question
Core area.
Bill
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"Why not the best?"
Jimmy Carter