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楼主 |
发表于 2008-12-26 09:14:22
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来自： 中国广东肇庆
这是一个老外的观点：
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What the "electrical power supply institute" said is correct.
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! a: M, s. D a" T) ?# CEveryone knows that electrons follow the path of lest resistance. 2 N, J$ f" x7 e* }3 X, _% K/ O
The smaller conductor has more resistance/distance than a larger conductor. It should see less current than the larger conductors but more heat too. % s# V, ?! s& v) M$ D# e) X4 R
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This is only part of the story!, t& T; }- n, ^; q7 _# b
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"The charge is located more at the point".
5 z7 r& V, K% t# U8 w9 i9 uElectrons naturally travel toward the surface of a conductor and they will also congregate around the smaller radius of an irregular cross section. The conductor as a whole must be able to dissipate the heat! (I believe that using two conductors of different diameters creates and irregular cross section without being able to share the heat.)
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The two large conductors lead in heating up as they do more current is shifted to the smaller conductor increasing it's temp until the point of failure. The "balance" is only good as long as the current doesn't cause the smallest conductor to exceed it's rating (3 times that of the smaller conductor.) V) }1 j) Z/ s6 g9 R# O) w# j: D
& b# d, N+ N. W# z: hThe smaller radius just compress the charge, whether it is moving or static. This wouldn't play apart in our situation. (This only come in to play someone is trying to make or avoid making a spark. As in determining what the insulation requirement for cable at different voltages.) |
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发表于 2008-12-25 17:20:01