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Measurement Tutorial
3
High-voltage self-heating errors
If you apply more than 300 Vrms, self- heating occurs in the
digital multimeter's internal signal- conditioning components.
These errors are included in the digital multimeter's
specifications.
Temperature changes inside the digital multimeter due to
self- heating may cause additional error on other AC voltage
ranges.
AC current measurement errors (burden voltage)
Burden voltage errors, which apply to DC current, also apply
to AC current measurements. However, the burden voltage
for AC current is larger due to the digital multimeter's series
inductance and your measurement connections. The burden
voltage increases as the input frequency increases. Some
circuits may oscillate when performing current
measurements due to the digital multimeter's series
inductance and your measurement connections.
Low-level measurement errors
When measuring AC voltages less than 100 mV, be aware
that these measurements are especially susceptible to errors
introduced by extraneous noise sources. An exposed test
lead acts as an antenna and a properly functioning digital
multimeter will measure the signals received. The entire
measurement path, including the power line, acts as a loop
antenna. Circulating currents in the loop create error
voltages across any impedance in series with the digital
multimeter's input. For this reason, you should apply
low- level AC voltages to the digital multimeter through
shielded cables. You should connect the shield to the input
LO terminal.
U2741A User's Guide
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