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引用第3楼sinian519于2007-08-31 16:48发表的 :
& u" [# k, D( N" ?5 W9 x我也不是很熟悉,请看标准UL153,Clause140.2 # ]* y) X1 L( N* H# ?' y
根據這個圖就對了.9 H; S+ E- _# h
9 b2 L! w: L+ y" s9 m
不過根據這個設備的要求, 發現標準存在問題, 請對照上面的圖再看此條, 一直困惑中:
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4 e5 o8 y* X k$ \( }140.2.5 The measurement circuit for leakage current is to be as illustrated in Figure 140.1. The
1 F4 ?- U& I( {measurement instrument is defined in (a) – (c). The meter that is actually used for a measurement is
# e5 h5 X& U X4 \& G, ?required to only indicate the same numerical value for a particular measurement as the defined
$ Z) x& B A& _9 z. g kinstrument. The meter used is not required to have all the attributes of the defined instrument.8 r" [. h$ y7 S1 I+ r6 i
a) The meter is to have an input impedance of 1500 ohms resistive shunted by a capacitance
7 C# y8 Y( [6 C- D+ X( ?6 |+ mof 0.15 microfarad.
. X, ^# E/ c! Z" ]" z% \3 t2 ]b) The meter is to indicate root mean square values which is 1.11 times the average of the fullwave* _* |( _9 r) ]+ A
rectified composite waveform of the current through the resistor.* a( h* z% p0 {2 ]2 f5 P
c) Over a frequency range of 0 – 100 kilohertz, the measurement circuitry is to have a. B m w0 B& q* U
frequency response – ratio of indicated to actual value of current – that is equal to the ratio of
+ L; N5 n; b8 Vthe impedance of a 1500 ohm resistor shunted by a 0.15-microfarad capacitor to 1500 ohms. At2 n: W6 o o( U& `% p% \5 |% k) j- F
an indication of 0.5 milliamperes, the measurement is not to have an error of more than 5' P. Y( P7 r! C: F
percent at 60 hertz. |
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