DSH 432 Protective Impedance versus no-load voltage

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DSH 432 % ?, Z5 J! g* X2 l( ?6 t9 s . d4 w, E: ~  d

Protective Impedance versus no-load voltage

18f)

60601-1(ed.2);am1;am2 - N, L7 p  X* b' l

( k- i  v4 ]$ qStandard(s)- (year and edition):
' R* S2 j: n  B4 [% X5 FIEC 60601-1:1988 Ed.2 Am1+Am2
Sub clause(s): 18f)
Sheet n°: DSH-432
5 |4 m9 ?; T+ q' y$ \Subject: Protective Impedance versus noload voltage
Key words: Protective, impedance, earth, connection, no-load
! k* [5 T" v# S' m. uConfirmed by CTL at its 39th meeting, in Cologne
$ a$ J7 o: Y: O$ BQuestion:
' G  ]0 Y) \# U* L1 `9 S! M" L1 YEQUIPMENT for example having a rated current of 30 A require a test current of 1.5 times 30 A.
+ h1 s- V6 v% [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
7 T8 {3 A, n" P2 u: v, j' Nin contradiction to the required no-load voltage of 6 V maximum.
% a0 c* _" N9 I8 `# b1 |" CDecision:
. [2 H/ p* ^8 w' z. ^/ i/ s6 GMeasuring the protective earth connection has in fact two reasons. It is to determine impedance
" ~9 P% f0 I' e" c, @( ]and cross-sectional area of protective earth connections. For a measuring current of 25 A both
can be done with one measurement. Requiring a measuring current of more than 25 A it shall be
4 U% D. t0 k5 s" z: Hsplitted up into two measurements. In this case, the impedance shall be determined first, using a
voltage not exceeding 6 V.
If cross-sectional area of the protective earth connections cannot be determined as equal to the
  O" S/ W9 ]7 ~6 Gone for the phase by measurement of the area, then measurement with current shall be from a
source with a higher voltage than 6 V.

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