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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:
6 |& D4 _7 L: A Q5 `9.7 Internal earthing circuit in cable reels, including any joints contacts and the like, shall be of low
; |# v9 D0 z- W6 b. j" q% yelectrical resistance.
8 \7 l s* f6 g0 c: uCompliance is checked by the following measurement which is made after the test specified in Clause 21.
$ p Z% U8 W2 k! o! V r8 C. qA current derived from an a.c. source, having a no load voltage not exceeding 12 V, and equal 1.5 times rated) e" t5 J! ^1 D# T1 }
current of the cable or 25 A, whichever is the greater, is passed through the earthing circuit.
# d$ O7 _9 j! B7 O0 O- q" |The voltage drop is measured and the resistance calculated from the current and this voltage drop.) r, _1 Q5 ] u
The resistance shall not exceed 0,05 Ω..
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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, + z) _: k3 t6 m7 O0 n2 {+ f
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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4 v$ l5 ]. Y' N6 h8 \: b8 J- }! h7 Z希望大家能讨论一下,指点迷津..谢谢~!! |
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