RE: [CAD_CAM_EDM_DRO] Re: What is Rms?

I didn't mean that to sound as abrupt as it did, sorry.

I just want to make it clear that the average value of a time-variant
waveform is NOT a good number to use in calculating the amount of work
that waveform can do.

Jon Elson's example a few posts back was very illustrative, and I intend
to use it whenever I need to make this point in the futture.

Andy Wander


Andy Wander
Verrex Corporation

-----Original Message-----
From: CAD_CAM_EDM_DRO@yahoogroups.com
[mailto:CAD_CAM_EDM_DRO@yahoogroups.com] On Behalf Of Andy Wander
Sent: Sunday, November 27, 2005 7:53 PM
To: CAD_CAM_EDM_DRO@yahoogroups.com
Subject: RE: [CAD_CAM_EDM_DRO] Re: What is Rms?

Graham:

...and MY point was that the "Average" of the voltage means nothing when
it comes to the effective amount of work done by it. The only way to get
this is by using rms clculations.




--- In CAD_CAM_EDM_DRO@yahoogroups.com, "Andy Wander" <awander@v...>
wrote:

>
> Graham:
>
> I believe that the only voltage that will give you correct

"effective" voltage number by averaging it to get the "effective"
voltage, is a square wave, or strauight DC, or changing DC which changes
as if it were a square wave(very quick transitions from voltage to
voltage).

>

Any periodic waveform that is always positive will work if you average
it, it can vary quickly or slowly.

My point was to illustrate what RMS represents, that's all.

Another point is that you can calculate an expression for the RMS for
any periodic waveform, either from the mathematical expression for the
waveform or even from a scope trace (if you can be bothered) you just
root the mean square :)

Graham
O/





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