Appx.1
Appendix
Appx. 1 RMS and Average
Difference between the RMS and Average
When converting AC to RMS, 2 methods are available, “True RMS
method (True RMS indication)” and “Average method (Average
rectifying RMS indication)”.
In the case of the sine wave where no skew is included, the same
values are indicated in both methods. However, if the waveform is
skewed, a difference occurs between the 2 methods.
The DT4211 (Average value measurement model) uses the Average
method, and the DT4212 (True RMS measurement model) uses the
True RMS method.
In the true RMS method, the high frequency component is also
included and displayed.
In the average method, the input waveform is handled as a sine
wave where no skew is included (only single frequency). The
average of the AC signal is obtained, converted to the RMS, and
then displayed. If the waveform is skewed, a greater measurement
error occurs.
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