"William Sommerwerck" wrote in message
...
So are you saying that a meter that measures *true* RMS
anything -- power, current, volts -- will do so correctly even
if the waveform is asymmetric about the zero point? I always
believed that an even distribution about the zero point was a
requirement for an accurate representation of an RMS value.

The RMS value of a waveform has nothing to do with the shape or symmetry
of
the waveform.

Assuming the meter is correctly designed, yes. RMS has a clear, specific
definition, and if the measurement is correctly implemented, the reading
will be correct.

Two qualifications... If the waveform is non-periodic, the measured RMS
value will vary according to the sample period. Also, if the waveform
includes a DC component, and the meter blocks it with a capacitor, then
the
RMS reading will not include the DC component.


Ah, OK. Perhaps it's non-periodicity that I'm getting confused with. As I
say, college seems a long-haired good music time ago now ...

Arfa