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The relevant time constant is the product of the effective capacitance in microfarads and the2 o0 `. @! F: X. D
effective discharge resistance in megohms. If it is difficult to determine the effective
7 n, f2 w; a1 y4 f# r; U! n3 P+ Rcapacitance and resistance values, a measurement of voltage decay at the point of external
0 Z' Q0 ?0 C; i9 z: F% {' [disconnection can be used. When conducting the voltage decay measurement, the result is
% s9 l% G1 M C# z4 Rreferred to an instrument having an input impedance consisting of a resistance of
9 F! F2 x% t" h( R X100 MΩ ± 5 MΩ in parallel with an input capacitance of 20 pF ± 5 pF.
l; r P8 F, j5 M; P3 t# h从标准的内容来说,确实是要求100 MΩ ± 5 MΩ 阻抗,但是我个人觉得阻抗越大,分流就越小,测到的数据就越接近真实情况。但标准不知道是怎么考虑的,为什么不在100M前面加上at least 之类的字眼。 |
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