求助：工作电压共地问题

keven2012

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  l) j$ u9 o! a, N1 j- X
工作电压测量的共地问题，次级地共N的依据来源于哪里了？

zhupinchao

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浪漫罗丹

仔细阅读62368下面条款
5.4.1.8 Determination of working voltage
5.4.1.8.1 General
In determining working voltages, all of the following requirements apply:
a) unearthed accessible conductive parts are assumed to be earthed;
- h( B+ f( O' a4 D6 db) if a transformer winding or other part is not connected to a circuit that establishes its
potential relative to earth, the winding or other part are assumed to be earthed at a point by
which the highest working voltage is obtained;
c) except as specified in 5.4.1.6, for insulation between two transformer windings, the highest
voltage between any two points in the two windings is the working voltage, taking into
account the voltages to which the input windings will be connected;
5 x! s% r# L7 a+ D$ md) except as specified in 5.4.1.6, for insulation between a transformer winding and another
part, the highest voltage between any point on the winding and the other part is the working
voltage;
4 G/ a! x" v6 W; g6 s9 Z
e) where double insulation is used, the working voltage across the basic insulation is
determined by imagining a short-circuit across the supplementary insulation, and vice
7 p5 D- h' a: W4 q0 u7 u! m, Vversa. For double insulation between transformer windings, the short-circuit is assumed
to take place at the point by which the highest working voltage is produced across the
5 o0 w4 L& ]. d9 p, n5 k4 [  iother insulation;
# d9 [, f6 l& I/ sf) when the working voltage is determined by measurement, the input voltage supplied to the
4 P' L! i# ~- L1 U* j0 Iequipment shall be the rated voltage or the voltage within the rated voltage range that
results in the highest measured value;
g) the working voltage between any point in the circuit supplied by the mains and
– any part connected to earth; and
– any point in a circuit isolated from the mains,
  N( C& A) l# P. cshall be taken as the greater of the following:
– the rated voltage or the upper voltage of the rated voltage range; and
3 e% A# m* D" B' ]/ m- p! t– the measured voltage;
h) when determining the working voltage for an ES1 or ES2 external circuit, the normal
operating voltages shall be taken into account. If the operating voltages are not known, the
working voltage shall be taken as the upper limits of ES1 or ES2 as applicable. Short
6 p) Q$ H8 h7 B5 P5 g# M! N% nduration signals (such as telephone ringing) shall not be taken into account for determining
working voltage;
+ ?# K1 [) G& \  ?i) for circuits generating starting pulses (for example, discharge lamps, see 5.4.1.7), the
+ j* f! E/ k* d# P. wworking voltage is the peak value of the pulses with the lamp connected but before the
lamp ignites. The frequency of the working voltage to determine the minimum clearance
shall be taken as less than 30 kHz. The working voltage to determine minimum creepage
$ H& W* D/ j. O6 N0 \distances is the voltage measured after the ignition of the lamp.

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