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EN 61242中关于线盘的接地电阻的测量中,有如下规定:+ x6 o4 ^5 K+ K8 G
9.7 Internal earthing circuit in cable reels, including any joints contacts and the like, shall be of low
6 w. Y. l, v( [$ a2 Y: j; i# telectrical resistance.
n, t+ c |" m9 D) f" rCompliance is checked by the following measurement which is made after the test specified in Clause 21.( q) @1 X6 l$ m: j4 P& U
A current derived from an a.c. source, having a no load voltage not exceeding 12 V, and equal 1.5 times rated: u& P' d l2 ^( c
current of the cable or 25 A, whichever is the greater, is passed through the earthing circuit.. E7 D' ~ X6 T$ K' J& O, I& [5 h' A0 d# y/ x
The voltage drop is measured and the resistance calculated from the current and this voltage drop.* J. S* T& O. }! \) p; {5 W
The resistance shall not exceed 0,05 Ω..
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: n- j, U% h9 n- b2 J0 R: l0 [测量时,发现如果包含其线盘所带的电缆在内测接地电阻,是绝对大于0.05的,而且主要的电阻产生于电缆本身,
3 x, F- r) a" v, G我知道在60335中测接地电阻时将电源线是排除在外了的,但是在这个标准里面并没有提到这一点,但是考虑到一般电缆在一定长度下也达不到0.05的限值,那是否意味着这时也应将电源线排除在外呢?但有个问题就是,如果将电源线排除,那么绞线盘的接地电阻还有什么意义呢?
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希望大家能讨论一下,指点迷津..谢谢~!! |
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