Theory Of Operation; Ac Voltage Measurements And Crest Factor - Keithley 2110 Reference Manual

In this section:

AC voltage measurements and crest factor ............................. 4-1

DMM resistance measurement methods .................................. 4-3
Reference junctions ................................................................. 4-4
Accuracy calculations ............................................................... 4-5
AC voltage measurements and crest factor
The root-mean-square (RMS) value of any periodic voltage or current is equal to the value of the DC
voltage or current which delivers the same power to a resistance as the periodic waveform does.
Crest factor is the ratio of the peak value to the RMS value of a particular waveform. This is
represented by the following equations:
The crest factor of various waveforms is different, because the peak-to-RMS ratios are variable. For
example, the crest factor for a pulse waveform is related to the duty cycle; as the duty cycle
decreases, the crest factor increases. The RMS calculations and crest factor (CF) for various
waveforms are shown in the following figures.
Equation 1: AC voltage measurements and crest factor (1)
Figure 30: RMS calculations and crest factor — sine
Figure 31: RMS calculations and crest factor — half-wave rectified sine
Section 4

Theory of operation