True Rms Ac Measurements - Keysight 34450A Guia Del Usuario

True RMS AC Measurements

True RMS responding multimeters, like the 34450A, measure the "heating"
potential of an applied voltage. Power dissipated in a resistor is proportional to
the square root of an applied voltage, independent of the waveshape of the signal.
This multimeter accurately measures true RMS voltage or current, as long as the
wave shape contains negligible energy above the instrument's effective
bandwidth.
Note that the 34450A uses the same techniques to measure true RMS voltage
and true RMS current.
The multimeter's AC voltage and AC current functions measure the AC-coupled
true RMS value. In this Keysight instrument, the "heating value" of only the AC
components of the input waveform are measured (DC is rejected). As seen in the
figure above; for sinewaves, triangle waves, and square waves, the AC-coupled
and AC+DC values are equal since these waveforms do not contain a DC offset.
However, for non-symmetrical waveforms, such as pulse trains, there is a DC
voltage content, which is rejected by Keysight's AC-coupled true rms
measurements. This can provide a significant benefit.
Keysight 34450A User's Guide
Measurement Tutorial 3
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