Is Flat Wire More Efficient for Generator Windings?

[R3KR]

Hello all, I have a simple question about copper windings on generators.

From what I have read, magnetism only penetrates the skin of a copper wire by very little.
Dosnt this mean that most of the copper in a winding is wasted ?

And wouldn't it be more efficient to use flat wire "-" instead of round "o" ?

 

[Bob S]

Magnetism completely penetrates copper at dc or very low frequencies. At ac frequencies, the penetration depth is called the skin depth. There are two situations where the copper dimensions are important. 1) For current being carried in copper conductor, the ac current tends to be carried on the surface, limited to the skin depth, so sometimes rectangular wire is perferred (but also for packing efficiency and mechanical considerations). Hollow water-cooled copper conductor is always square or rectangular. 2) Eddy currents can be generated (and dissipated) in copper wires exposed to ac magnetic fields. this leads to heat dissipation that has to be removed. The orientation of the flat surfaces of the conductor relative to the magnetic field direction is important.
Bob S

 

[R3KR]

Thanks for reply!

Was thinking in terms of 3 phase AC, don't know if "frequency" would be considered to be DC. 50-200Hz ?

When you say "orientation", I am assuming that the "plane side" of flat wire is perpendicular to the magnets pole,

 

[Bob S]

Skin depth in copper is about 8 mm at 60 Hz, and varies inversely as sqrt(frequency). For rectangular copper conductors, the long dimension should be parallel to the magnetic field.
Bob S