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|  DSH 432
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q2 _5 O4 ^: S( z | Protective Impedance versus no-load voltage
+ g) _* [0 o" v0 D" x+ j | 18f)8 N! B" t$ i, j$ Q9 t2 R
| 60601-1(ed.2);am1;am24 C% A3 i: J8 K! U |9 L6 ]
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) e& l3 K/ ^0 C; }( {/ D x9 |Standard(s)- (year and edition):
% w5 L" V3 Y1 o/ ]IEC 60601-1:1988 Ed.2 Am1+Am25 j$ h; d, d: R* m6 r% E n
Sub clause(s): 18f)0 S3 H$ n ^& d* s7 o: U
Sheet n°: DSH-432
$ j: j0 ?2 u3 l$ d5 \; ASubject: Protective Impedance versus noload voltage% ^4 L/ [( G4 n+ `% P5 h: s
Key words: Protective, impedance, earth, connection, no-load- e6 W7 d5 S4 K Q1 B/ R
Confirmed by CTL at its 39th meeting, in Cologne' L3 G/ K) a* U7 F( n
Question:
& V6 o1 l3 j8 V# _9 l# ^EQUIPMENT for example having a rated current of 30 A require a test current of 1.5 times 30 A.0 k7 [$ c; e' s2 k! T5 ?0 ^
With a maximum impedance of 0.2 W the voltage drop has to be 9 V (0.2 W * 45 A = 9 V). This is
3 [/ @5 Y, m: c- J, F% xin contradiction to the required no-load voltage of 6 V maximum.1 C( P, J% {# f5 w' l* x, ]
Decision:: A# {: c# |- z$ C# G7 S
Measuring the protective earth connection has in fact two reasons. It is to determine impedance) s, u/ o* X, O U1 ]4 [* N4 J
and cross-sectional area of protective earth connections. For a measuring current of 25 A both
9 N/ c0 ?4 I% K6 Z6 Rcan be done with one measurement. Requiring a measuring current of more than 25 A it shall be: j |5 [3 n1 h3 n# q) G4 ?% N+ Y* a
splitted up into two measurements. In this case, the impedance shall be determined first, using a
5 {. x( u9 n; V. F! o! Nvoltage not exceeding 6 V.7 O# |* r) g/ e$ r* `
If cross-sectional area of the protective earth connections cannot be determined as equal to the
( O7 u+ ^4 v8 [0 Zone for the phase by measurement of the area, then measurement with current shall be from a {, o& A7 J5 T' @) X) g6 s
source with a higher voltage than 6 V.
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发表于 2012-11-5 10:22
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