User`s guide

Measurement Tutorial 3
34450A User’s Guide 97
Temperature changes inside the 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 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 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
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 impedances in series with the
multimeter’s input. For this reason, you should apply
low- level AC voltages to the multimeter through shielded
cables. You should connect the shield to the input LO
terminal.
Make sure the multimeter and the AC source are connected
to the same electrical outlet whenever possible. You should
also minimize the area of any ground loops that cannot be
avoided. A high- impedance source is more susceptible to
noise pickup than a low- impedance source. You can reduce
the high- frequency impedance of a source by placing a
capacitor in parallel with the multimeter’s input terminals.
You may have to experiment to determine the correct
capacitor value for your application.