User`s guide

96 34450A User’s Guide
3 Measurement Tutorial
Other Sources of Measurement Error
Loading Errors (AC volts)
In the AC voltage function, the input of the multimeter
appears as a 1 MW resistance in parallel with 100 pF of
capacitance. The cabling that you use to connect signals to
the multimeter also adds capacitance and loading.
For low frequencies, the loading error is:
At high frequencies, the additional loading error is:
Measurements Below Full Scale
You can make the most accurate AC measurements when the
multimeter is at or near the full scale of the selected range.
Autoranging occurs at 10% (down- range) and 120%
(up- range) of full scale. This enables you to measure some
inputs at full scale on one range and 10% of full scale on the
next higher range. In general, the accuracy is better on the
lower range; for the highest accuracy, select the lowest
manual range possible for the measurement.
High-Voltage Self- Heating Errors
If you apply more than 300 V
rms
, self- heating occurs in the
multimeter’s internal signal- conditioning components. These
errors are included in the multimeter’s specifications.
Error (%) =
–1 0 0 × R
s
R
s
+1MΩ
Error (%) =
R
s
=SourceResistance
F=InputFrequency
C
in
= Input Capacitance (100 pF) Plus Cable
Capacitance