connections

[artv]

Hi all,... I wound a test coil two in hand,.....It's small guage wire ~20-24......Do I connect the two starts together, and the ends together to give me two outputs??......Or do I connect the "end" of one start, to the start of the parallel winding??......Leaving me with the start of one winding as an out,....and the end of the other for an out.......was trying to figure out what two wires running parallel would benifit .........never thought about the connections..........thanks for your time......artv

[GoVertical]

Greetings, I just made a large single phase, 2 in hand 22 AWG. Before that I made a large single phase 4 in hand 22 AWG.  Then based on the electric brake action that occurred when I shorted the outputs together as the rotors were spinning the 4 in hand had a much stronger braking action, so much that it caused the PMA to physically show movement when sitting unsecured on the test bench.  The multiple wires were connected in parallel in the coil.  The PMAs are the same size, same rotors, same magnets.  Based on my observation 4 in hand produced more current with less turns. The parallel connection reduced the stator resistance.  From what I read lower stator resistance improves output efficiency at higher RPMs.  Hopefully other will support my findings. 

[ghurd]

A "Test Coil" is to determine the voltage per RPM.

2 in hand is to reduce the resistance per turn of the coil.  They are connected in parallel.

No reason to use 2 in hand for a test coil.

Since you already have a '2 in hand' coil, I would suggest connecting the 2 wires in series.  (start of one to end of the other)  It would give double the voltage per RPM for more accurate calculations.
G-

[Flux]

I think there is some mistaken belief that winding coils in hand has some magical properties, I keep seeing similar comments.

The misconception probably comes from the belief that using 2 wires in parallel gives a lower resistance that is beneficial. Although true the available space is halved and so the turns have to be halved.

Neglecting the effects of eddy currents in large conductors, winding turns in hand is just a tool to adapt a certain wire size to a certain voltage rather than using a more suitable wire. There is no magical gain. If you connect in series then it is just twice as many turns. if you connect in parallel then the same number of turns but twice the csa. If you don't use both sections in one way or the other then it is just a waste of space and effort.

I agree with ghurd that for a test coil just wind it all in series to get the best voltage for measurement but i suspect that was not really the intention of the question.

Flux

[GoVertical]

Greetings, I was thinking about my less post and I may have misspoke. I made some test coils using 22 AWG.

1 in hand @ 200 turns       output @ 200 RPM = 1.3 VAC
2 in hand @ 100 turns       output @ 200 RPM = 0.7 VAC
4 in hand @ 50 turns         output@ 200 RPM =  0.3 VAC
8 in hand @ 25 turns         output@ 200 RPM = 0.16 VAC


I apologize to the forum and anyone reading my last post. 

[Flux]

That all makes perfect sense. Your volts are proportional to the number of turns so your readings are accurate. The resistance will drop with the number of parallel circuits.

With a given size wire you can get the combination that gives you optimum turns. The power out will be the same in each case if you properly match the voltage but obviously if you don't do this the power will be greatest in the coil that matches your requirements.

One point I didn't make previously was that using multiple strands of thinner wire usually gives a better stacking factor than a single thicker wire as the thin turns nest better in the gaps between layers. Apart from eddy loss using very thick wire often gives a poor stacking factor unless you use square or rectangular wire.

Flux

[ghurd]

Greetings, ...

I will try to hack through some confusion here in a short summary, but be advised I am not in a great mood.

The whole thing could be proved with one test coil, one RPM, and a calculator, in 1 minute.

#1.  Those findings 111% completely agree with what we said.  It would be far less confusing if the "X in hand" were ignored.
#2.  So does "the electric brake action".

#1A.  Ignore the 1~8 in hand, and look at the voltage per turn.  They are the same.
#2A.  Less resistance and shorted makes a better electric brake.  And 8 in hand has only 12% the resistance of 1.

#3.  The flux path in the photos of the lathe test is totally incomplete, and even less complete than than the "working version".  
I doubt the test results shown prove anything relative, except that in the same magnetic field, doubling the turns in a coil doubles the unloaded voltage, which everone knows.
#3A.  Shorting a coil with the same number of turns and a lower resistance will make "the electric brake action" more pronounced, which everyone knows.
#3B.  AWG# minus 3 = Two in hand.  Two #22 in hand = one #19.  Four #22 in hand = Two #19 = one #16.

#4.  Everything in #3 was common knowledge 100 years ago.  Maybe >125 years ago.
You can do some VERY fine worksmanship on the materials and assembly, but you need to read and comprehend what people point you toward.

#1A1.  
Volts per turn per RPM. is the same in the same magnetic field.
1.3V / 200 turns / 200RPM = 0.000,032,5
0.16V / 25 turns / 200RPM = 0.000,0032,0
The result is closer than the margin of error, and closer than the meter can read?
(personally, I am sort of impressed they came out that close under the test conditions, though I won't expand on the concepts)
Congratulations?  You spent a great deal of time, money, and resources, to prove what we were telling you months ago.

[GoVertical]

Wow, think pleasant thoughts, it always starts out to be a nice day. Can you provide links to what was covered 100 year ago? I did a search and I could not find any references.  I hope your feel better in the future.

[joestue]

there's hundreds of books on the subject

http://www.archive.org/details/electricalengin01fostgoog
i have a hard copy of this book, its a good overview of the state of the industry in 1900-1910, all of the theory is in metric, but its light on electric motors.

this publisher has a number on the subject. most everything is on google these days.
http://www.archive.org/search.php?query=publisher%3A%22D.%20Van%20Nostrand%20company%22&page=1

even in 1900 windage and friction was half the losses, iron and copper the other. so basically machine design hasn't changed that much. it wasn't until silicon steel came about and they solved the aging problem that you could run the flux higher than 5-60,000 lines per inch^2 or 0.8 to 0.9T
electricity cost the same in 1910 as it does today... they cared a great deal about efficiency. 

[Simen]

Besides getting better stacking of the wires when winding x-in-hand, wouldn't we also get a more robust coil - Amp-wise and cooler-running?
(Maybe that's what Ghurd was implying with the 'Electrical brake action'? )

[ghurd]

From 200 to 150 years ago;
Michael Faraday did much of his work between 1821 and 1839, building his generator in 1831.
Georg Ohm worked out Ohm's Law in 1825 and 1826, published Die galvanische Kette, mathematisch bearbeitet in 1827.
Ampere had his law ready in 1826.
Heinrich Lenz had his law worked out in 1833.
Carl Gauss had his law worked out in 1835.
Joule's law was known in the 1840s.
James Maxwell published his equasions in 1861 and 1862.

[SparWeb]

Ghurd, you forgot Nik and Tom.

Not quite 150 years ago, though.