Measurements Below Full Scale; High-Voltage Self-Heating Errors; Ac Current Measurement Errors (Burden Voltage); Low-Level Measurement Errors - DATATEC EDU34450A Guia Del Usuario

At high frequencies, the additional loading error is:

Measurements Below Full Scale

You can make the most accurate AC measurements when the instrument 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 Vrms, self-heating occurs in the instrument's internal signal-conditioning components.
These errors are included in the instrument's specifications.
Temperature changes inside the instrument 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 instrument'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 instrument'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 instrument's
input. For this reason, you should apply low-level AC voltages to the instrument through shielded cables. You should
connect the shield to the input LO terminal.
Make sure the instrument 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 instrument's input terminals. You may have to experiment to
determine the correct capacitor value for your application.
Keysight EDU34450A User's Guide 111