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The relevant time constant is the product of the effective capacitance in microfarads and the8 L$ M4 T, V9 O2 X9 Y' {8 R
effective discharge resistance in megohms. If it is difficult to determine the effective
' w: k4 O1 y6 v, m( w7 Z5 ?capacitance and resistance values, a measurement of voltage decay at the point of external
8 j% Q" }0 f/ Sdisconnection can be used. When conducting the voltage decay measurement, the result is8 Y* V7 h8 ?4 f
referred to an instrument having an input impedance consisting of a resistance of
, D% g, O, m! n, B8 |5 e100 MΩ ± 5 MΩ in parallel with an input capacitance of 20 pF ± 5 pF.& a2 E, N+ L* C. P& j" |
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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