Solid vs Stranded wire
- Thread starter Eclectic
- Start date
Motor windings aren't subject to significant flexing - they are fixed in placed with resin. The phase ends are tied to the stator support.
Scott, did you assume that the different types of wire used the same composition for the conductor? There are lots of possibilities for variation with "copper" wire which would affect its electrical resistance.
Scott, did you assume that the different types of wire used the same composition for the conductor? There are lots of possibilities for variation with "copper" wire which would affect its electrical resistance.
Punx0r said:
That is true.
Both the low stranded and solid wires were just copper with out any plating on them. However the high stranded wire is plated with Aluminum or something which could make a difference.
What other variations are you thinking of?
dnmun
1 PW
you would have to normalize your data with respect to the true cross sectional area of the wire.
a collection of stranded wires which have the same cross section will have the same conductivity if they are the same purity of copper. stranded will not make any difference in the conductivity.
like i told the original poster, it is ok to use solid wire like the rest of us do when the wire is not subject to severe repeated flexing which would work harden and then cause stress fractures internally. he was gonna use solid where he taped it to the frame and stranded on the ends where it went to the controller from what he said back then.
a collection of stranded wires which have the same cross section will have the same conductivity if they are the same purity of copper. stranded will not make any difference in the conductivity.
like i told the original poster, it is ok to use solid wire like the rest of us do when the wire is not subject to severe repeated flexing which would work harden and then cause stress fractures internally. he was gonna use solid where he taped it to the frame and stranded on the ends where it went to the controller from what he said back then.
friendly1uk
1 MW
dnmun said:
The rest of you in your minority. Some would even solder the flex to the hardcore and think it a good connection. It aint right though.
dnmun
1 PW
what does it mean when you say it ain't right? how can you somehow make up this stuff that stranded conducts better when it is not grounded in the laws of physics? conductivity is based on cross sectional area and purity of the copper. stranded THNN is made so that it can be pulled through conduit. nothing else.
Scott,
This link just happened to the first one I saw on a quick Google search: http://www.copper.org/publications/newsletters/innovations/1997/12/wiremetallurgy.html
It doesn't describe the effect on conductivity of specific impurities, but confirms that they can have a significant affect in very small quantities. If "copper" is >99.3% Cu then there's room for 0.7% of junk that could be having a deleterious effect on conductivity. It would be interesting to see the result of an experiment measuring the resistance of good quality and cheap-and-nasty wire of the same size.
I suspect there may also be some variation in the cross-sectional area of two wires that claim to the same AWG size. It might be necessary to measure a strand (or several and average if necessary) under microscope or shadowgraph and multiply by the strand count. Or strip the insulation and compare wire samples by weight.
This link just happened to the first one I saw on a quick Google search: http://www.copper.org/publications/newsletters/innovations/1997/12/wiremetallurgy.html
It doesn't describe the effect on conductivity of specific impurities, but confirms that they can have a significant affect in very small quantities. If "copper" is >99.3% Cu then there's room for 0.7% of junk that could be having a deleterious effect on conductivity. It would be interesting to see the result of an experiment measuring the resistance of good quality and cheap-and-nasty wire of the same size.
I suspect there may also be some variation in the cross-sectional area of two wires that claim to the same AWG size. It might be necessary to measure a strand (or several and average if necessary) under microscope or shadowgraph and multiply by the strand count. Or strip the insulation and compare wire samples by weight.
Found good information about different copper cable qualitys. http://www.doublehelixcables.com/store/index.php?main_page=page_3
Well, I used to have the results of an unintentional experiment with car jumper cables, two sets, one a very old nice set, and one a brand new set from somewhere like Harbor Freight (don't know the actual vendor). Both appeared the same length, gauge and strand sizes, and both had what seemed like steel post clamps.Punx0r said:
A friend was trying to jump start his very-dead-battery big truck from another big truck, first with the new cables--just hooking them up they were getting warm enough to feel (in 50F-ish weather), before even trying to crank the truck, from the current the dead battery was pulling from the running truck. When he actually tried to crank the truck, it barely even tried to do anything, and after a few seconds we coudl see the cable insulation smoking.
He stopped and pulled those cables off, and he got the old cables out, put them on, and they didnt' get warm until after he'd been cranking for a bit, and this cranking was much faster and did have some results (but it still wouldnt' start; problem with the truck I dont' know what).
Later we looked at the damaged calbes and found a harddisk magnet would sort of stick to the bare wire....even though it looked like copper, it clearly wasn't *just* copper (perhaps it was only *plated* with copper--we dont' know). He gave me those cables cuz he never wanted to see them again and figured I could use them for something. AFAIK those cables (and most of my othe rstuff like that) vanished during the post-fire delays and cleanup and whatnot, so I can't tell you much more than that.
friendly1uk
1 MW
dnmun said:
You misunderstand. You seem to be addressing the op saying it is ok, the rest of us do it. I'm pointing out that the rest of us is not the rest of us, but the rest of the people that do it. Which is a little nonsensical. It offers no real weight to your viewpoint. My second comment about soldering is made as that is what people will do. Join with solder. Which would be the actual weak point caused by the wire stiffness. That is the practicality of this. If you want to talk qualification, we can. However I can't use that as some sort of ace card as it is not actually relevant. Wire purity is not relevant. Cross section is also not relevant as your not going to calculate the wire anyway. Only if we did would my qualifications in this area really shine. This is not really about size or quality or the effect of bending on cross section and imperfections. It is about the most basic of things people can get their heads round. It aint right. Though the actual problems are alluding people.
