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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:. Q6 U3 }. U7 K( i( T
9.7 Internal earthing circuit in cable reels, including any joints contacts and the like, shall be of low) Z' u/ h6 D! {3 u) T- [
electrical resistance.- u7 [4 Z- H D5 u8 ]
Compliance is checked by the following measurement which is made after the test specified in Clause 21.
( C+ V' @! i2 dA current derived from an a.c. source, having a no load voltage not exceeding 12 V, and equal 1.5 times rated
3 L# R9 J0 N2 D$ @0 zcurrent of the cable or 25 A, whichever is the greater, is passed through the earthing circuit.
: h- ]. e& ?# H2 \ Z4 \6 E% f3 p% [The voltage drop is measured and the resistance calculated from the current and this voltage drop., h% n U; n1 c4 e
The resistance shall not exceed 0,05 Ω..
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. p: n# d$ |& Y! O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,
8 t& {1 Q3 h3 y1 t# _- F% K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?
8 w+ y/ a% H- ?* C, l# ]6 a; o& p0 ?
希望大家能讨论一下,指点迷津..谢谢~!! |
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