202 Keysight E4981A 120 Hz/1 kHz/1 MHz Capacitance Meter
Specifications and Supplemental Information
Sample Calculation of Measurement Accuracy
10-
Sample Calculation of Measurement Accuracy
This section describes an example of calculating the measurement accuracy
for each measurement parameter, assuming the following measurement
conditions:
Measurement signal frequency 1 kHz
Measurement signal level 0.5 V
Measurement range 10 nF
Measurement time mode N = 1
Ambient temperature 28 °
C
When measurement parameter is Cp-D (or Cs-D)
The following is an example of calculating the accuracy of Cp (or Cs) and D,
assuming that measured result of Cp (or Cs) is 8.00000 nF and measured result
of D is 0.01000.
From Table 10-10, the equation to calculate the accuracy of Cp (or Cs) is
0.055+0.030×K and the equation to calculate the accuracy of D is
0.00035+0.00030×K. The measurement signal level is 0.5, the measurement
range is 10 nF, and the measured result of Cp (or Cs) is 8.00000 nF. Therefore,
K=(1/0.5)×(10/8.00000) =2.5. Substitute this result into the equation. As a
result, the accuracy of Cp (or Cs) is 0.055+0.030×2.5=0.13% and the accuracy
of D is 0.00035+0.00030×2.5=0.0011.
Therefore, the true Cp (or Cs) value exists within 8.00000±(8.00000×0.13/100)=
8.00000±0.0104 nF, that is, 7.9896 nF to 8.0104 nF, and the true D value exists
within 0.01000±0.0011, that is, 0.0089 to 0.0111.
When measurement parameter is Cp-Q (or Cs-Q)
The following is an example of calculating the accuracy of Cp (or Cs) and Q,
assuming that measured result of Cp (or Cs) is 8.00000 nF and measured result
of Q is 20.0.
The accuracy of Cp (or Cs) is the same as that in the example of Cp-D.
From Table 10-11, the equation to calculate the accuracy of D is
0.00035+0.00030×K. Substitute K=2.5 (same as Cp-D) into this equation. The
accuracy of D is 0.00035+0.00030×2.5=0.0011. Then, substitute the obtained
D accuracy into the equation specified in Table 10-6. The accuracy of Q is
±(20.0)
2
×0.0011/( ×0.0011) =±0.44/( ), that is, -0.43 to 0.45.
Therefore, the true Q value exists within the range of 19.57
to 20.45.
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