Power calculations can you check?

[xclr82xtc]

this is a power calcualtion using 1 magnet pair with the turbine turning at 1 rpm..34 inch diameter rotor. i hope someone else can make sure I am at least doing it right, and i need help converting my single phase numbers to 3phase wye
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coil info

1x1x2

80 turns total, 4 rows of twenty.

center line of coil is 34 inches.

the magnets making 1 revolution per minute would pass the coils at X coils per second...lets figure out X

circumference of a 34 inch circle = 106.8 inches

divide that by 60 seconds...106.8/60= 1.78

so EVERY SECOND...the magnets travel 1.78 inches. in turn, the magnetic fields pass through the coils at the rate of 1.78 inches per second?

am i right to this point?
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there is 80 coils in 2 inches, so in 1.78inches we would have 71.2

the tesla of the magnets is .6403
the area is .75inchx2inch then change to meters squared = 0.003610meters squared


faradays law

N = -1 * (-V/ (( tesla * area meters squared)/ seconds))

71.2=-1*(-V/((.6403*.003610)/1.78)



-71.2=(-V/.00129)
.0918=V


so right now we have 71.2 turns = ..0918 v at at rate of 1 rpm...
now there is 7 coils of 80 so that's 560 total turns
divide by 71.2 =7.87
so times 7.87 time the Voltage .0918

=.722 volts per phase...

my math looks more right this time lol
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now how many feet of wire in a coil (we need to find the resistance)


wire info

Nominal Diameter: 0.10 inch

Nominal OHMS/LB. -20 Celsius: 0.0314

Feet/LB: 31.48

outersize of coil is 1 inch. 4 layers and the core is .6inches.(yes this does take into account wire size) .so the perimter for one layer of turns is (.7*4)+(.8*4)+(.9*4)+.(1*4)=2.8+3.2+3.6+4=13.6inches

now the coil is 2 inches long so we need have 20 layers...20*13.6=272inches...divde by 12=22.6 feet or wire per coil...nice. lol

ok so now we know we have 7 coils so 22.6*7 = 158.2 feet.

its 31.48 feet per lb so 158.2/31.48=5.025lbs

5.025 * .0314=.1578

so the TOTAL resistance of all seven coils is .1578ohms


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so now we know the total voltage of one phase at 1 rpm of the mill, and we know the constant resistance of the coil. (i also have the inductance of each coil but i don't think we need it.)

so with this info, we SHOULD be able to figure out the amps using ohms law. i=v/r

.722/.1578=4.578AMPS

SOOOO...per phase, at 1 rpm we have 1.29 volts and 4.578amps. kinda crappy, but hey its only turning at 1 rpm, and that's only using 1 pair of magnets, there is 15 total pairs.

 

[anorlunda]

You can't do it that simply. Magnetic fields drop rapidly with distance from the source. Therefore, you need to estimate the field strength separately for each turn.

Software packages such as COMSOL can do the 3D modeling needed for that, but hand calculations are not practical.