求助：工作电压共地问题

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* _7 s3 D+ |* v9 A1 U  T0 [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？
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8 @- V; _: _1 `5 J3 Y

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仔细阅读62368下面条款
7 j( o* M& `2 Y4 S+ }$ `" R* N; L) ~5.4.1.8 Determination of working voltage
6 Y: M7 o( Y. ]4 q! L5 w( ^" l5.4.1.8.1 General
' g" |- B7 r0 XIn determining working voltages, all of the following requirements apply:
* [5 K4 a2 q2 y" _6 i$ p0 @% [a) unearthed accessible conductive parts are assumed to be earthed;
4 ~! Z. K$ Y/ V, Yb) if a transformer winding or other part is not connected to a circuit that establishes its
3 d, p0 v) C% W* z( t  `potential relative to earth, the winding or other part are assumed to be earthed at a point by
9 a7 _- N  V+ s3 \4 Bwhich the highest working voltage is obtained;
c) except as specified in 5.4.1.6, for insulation between two transformer windings, the highest
3 d/ e$ K3 z, bvoltage between any two points in the two windings is the working voltage, taking into
' o  d+ T1 B% L3 d1 M+ raccount the voltages to which the input windings will be connected;
. p4 x' [/ R* k$ p- t& |d) except as specified in 5.4.1.6, for insulation between a transformer winding and another
4 H/ i, V1 Q2 J2 }* Z7 ppart, the highest voltage between any point on the winding and the other part is the working
voltage;
  x0 u+ S" S4 u/ X8 Q, o, [
9 Y: S" H! s) i$ w$ ^2 te) 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
versa. For double insulation between transformer windings, the short-circuit is assumed
2 q8 _' U7 o9 b$ x6 z0 @: bto take place at the point by which the highest working voltage is produced across the
, v- z0 V2 `- \' {" Dother insulation;
f) when the working voltage is determined by measurement, the input voltage supplied to the
equipment shall be the rated voltage or the voltage within the rated voltage range that
# w1 ]  H( M8 x" H" r8 j9 K7 sresults in the highest measured value;
0 f9 a, f3 ~1 pg) the working voltage between any point in the circuit supplied by the mains and
5 A# @7 w6 ]! `: v+ h) B8 @– any part connected to earth; and
% j/ X. J! a7 t( z– any point in a circuit isolated from the mains,
shall be taken as the greater of the following:
– the rated voltage or the upper voltage of the rated voltage range; and
9 f) g/ y) z6 o7 q7 t– the measured voltage;
  T& n( E! f/ U+ s0 k: Ch) 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
2 T6 l& _# b' @  W/ O4 X: Jworking voltage shall be taken as the upper limits of ES1 or ES2 as applicable. Short
+ x. C3 Y4 m* K8 P/ g/ bduration signals (such as telephone ringing) shall not be taken into account for determining
$ N9 [, K" I6 S4 L' K- E. ]working voltage;
9 T3 w$ ]. o6 ti) for circuits generating starting pulses (for example, discharge lamps, see 5.4.1.7), the
! x4 c. [4 r# ^9 Y% a; lworking 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
. C5 c; h6 v/ G# Wshall be taken as less than 30 kHz. The working voltage to determine minimum creepage
distances is the voltage measured after the ignition of the lamp.

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