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Old 04-22-2014, 01:01 AM   #1
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Default Wire strand count

Gidday,

With regards to a certain gauge of wire, does the strand count affect the resistance/ voltage drop of the wire? I am wondering because it would mean the wire cross sectional area would be filled up more if there was a higher strand count for that given gauge of wire(I am guessing more strands of smaller wires). This might mean wire such as TQ and other popular brands may provide slightly more voltage for a given gauge compared to regular wire if my thinking is right??

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Mike
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Old 04-22-2014, 02:40 AM   #2
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Gidday,

With regards to a certain gauge of wire, does the strand count affect the resistance/ voltage drop of the wire? I am wondering because it would mean the wire cross sectional area would be filled up more if there was a higher strand count for that given gauge of wire(I am guessing more strands of smaller wires). This might mean wire such as TQ and other popular brands may provide slightly more voltage for a given gauge compared to regular wire if my thinking is right??

Thanks
Mike
I think it probably does however I prefer the high strand count wires for a different reason. They tend to be more flexible and easier to solder!
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Old 04-22-2014, 03:19 AM   #3
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it depends which school of physics you wish to subscribe to

some say its the total cross-sectional area of copper that flows the current.
I have a chunk of copper from local power station... yep they use solid
copper bars to carry their power

other boffins believe in "skin effect", that the current only travels along
the outer surface of copper wire so a multistrand wire multiplies this.
But a bundle of small round wires will leave airgaps between their circles
so you've got less copper cross-section vs a solid single core


plus on top... at their limit, wires may carry
Direct Current (from your battery) differently to
Alternating Current (pulse from ESC to motor).
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Old 04-22-2014, 03:25 AM   #4
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Quote:
Originally Posted by ixlr8nz View Post
Gidday,

With regards to a certain gauge of wire, does the strand count affect the resistance/ voltage drop of the wire? I am wondering because it would mean the wire cross sectional area would be filled up more if there was a higher strand count for that given gauge of wire(I am guessing more strands of smaller wires). This might mean wire such as TQ and other popular brands may provide slightly more voltage for a given gauge compared to regular wire if my thinking is right??

Thanks
Mike
I have been using TQ wire before he went into business. I was one of his testers. The wire is great and you are correct in your statement.

Contact Ralph and hw will be more then willing to answer any question you have. [email protected] Tell him "Blue" sent ya.
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Old 04-22-2014, 05:55 AM   #5
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Quote:
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...other boffins believe in "skin effect", that the current only travels along the outer surface of copper wire so a multistrand wire multiplies this.
They used to say that about the brushes in brushed motors.
But the effect only occurs at very high frequencies, far higher than we see in RC
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Old 04-22-2014, 06:18 AM   #6
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But the effect only occurs at very high frequencies, far higher than we see in RC
Incorrect.

Frequencies seen today the skin depth could be as low as 200um.
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Old 04-22-2014, 07:08 AM   #7
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Incorrect.

Frequencies seen today the skin depth could be as low as 200um.
That sounds bigger than the size of strands we use (depending on the wire)
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Old 04-22-2014, 07:45 AM   #8
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The number of strands is important for flexibility, but not much else. It only has a small effect on resistance at higher frequencies, because the strands are in contact with each other.

Wire that is manufactured to minimize skin effect has each strand insulated from the others. This is called Litz wire, and it's very rare. An electrical engineer could go an entire career and never see it. I only saw it once, and that's when I special-ordered it.
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Old 04-22-2014, 08:33 AM   #9
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Correct.

Options are foil or litz wire. RC applicaiton litz wire is the best option price isn't that bad if you buy in large quanity. Industry often use home made litz wire.

The current draw at high rpm where wire resistance is high is reasonably low. With a decent cap close to the ESC and short motor wires we can get away without litz wire.
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Old 04-22-2014, 08:36 AM   #10
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In theory, yes...

In practice, not so much...

The quality of solder joint makes a much larger difference than a few extra strands of wire.
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Old 04-22-2014, 09:03 AM   #11
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Quote:
Originally Posted by whitrzac View Post
The quality of solder joint makes a much larger difference than a few extra strands of wire.
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Old 04-22-2014, 09:54 AM   #12
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I can vouch for the quality of my soldering, no probs.

But have you guys ever cracked open a lipo hardpack to check how crap the bag cells are soldered up??
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Old 04-22-2014, 01:01 PM   #13
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You guys really now your stuff. Good job guys. I just knew that more strands made the wire more flexible.
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Old 04-22-2014, 01:24 PM   #14
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I thought AWG defined the circular mills of the wire? Therefore, depending on the packing efficiency of the strands, the OD for a stranded wire with a specific gauge could fluctuate. Could be wrong though, haven't read the spec. If true, then strand count wouldn't matter to a DC voltage drop, all else equal.
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Old 04-22-2014, 05:27 PM   #15
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Quote:
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I thought AWG defined the circular mills of the wire? Therefore, depending on the packing efficiency of the strands, the OD for a stranded wire with a specific gauge could fluctuate. Could be wrong though, haven't read the spec. If true, then strand count wouldn't matter to a DC voltage drop, all else equal.
AWG indicates the total cross-sectional area of the wire, regardless of how it is stranded. The OD is a little larger for stranded versus solid, but the resistance is the same.
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