Measurement Tutorial
3
Keysight U2741A User’s Guide
55
AC Measurements
True RMS AC measurements
True RMS responding digital multimeter, like the U2741A, measure the “heating”
potential of an applied voltage. Power dissipated in a resistor is proportional to
the square of the voltage waveform. This digital multimeter accurately measures
true RMS voltage or current, as long as the wave shape contains negligible energy
above the instrument's effective bandwidth.
NOTE
The U2741A uses the same techniques to measure true RMS voltage and true
RMS current.
Table 3-3
Waveform shapes and their parameters
Waveform shape
Crest factor (CF)
AC RMS
AC+DC RMS
2
V
2
-----
V
2
-----
3
V
3
-----
V
3
-----
T
tp
-------
V
CF
-----
1
1
CF
-----
⎝
⎠
⎛
⎞
2
–
×
V
CF
-----
1
V
V
