**From:** Zabinski, Patrick J. (*zabinski.patrick@mayo.edu*)

**Date:** Tue May 29 2001 - 12:59:37 PDT

**Next message:**Larry Miller: "RE: [SI-LIST] : RMS Definition"**Previous message:**Doug Brooks: "[SI-LIST] : RMS Definition, clarification"**Maybe in reply to:**Doug Brooks: "[SI-LIST] : RMS Definition, clarification"

Vrms = Sqrt[ Integral (V(t)^2) ] / T

Where:

V(t) = Voltage with respect to time

T = one period of time = boundaries of integral

Simply insert the equation for V(t) into the integral,

integrate over one period, and you can figure out Vrms

for any (deterministic, periodic) waveform.

In terms of a table of values, you've got the most

common ones already listed. Sorry, I don't have

any handy-dandy, all-inclusive chart.

One point to keep in mind, though, is that you should

be clear in what "V" represents in your table. Some folks

assume "V" means Vpeak-to-peak, while others assume "V"

means Vpeak-to-ground. Similarly, don't forget to take into

account DC offsets (some folks assume "square wave"

means Zero to V, not -V to +V; etc.).

Pat

*>
*

*>
*

*> Sorry if I wasn't clear. I know what RMS means. What I am
*

*> looking for is an
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*> equation of the form
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*>
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*> RMS = sqrt[integral(V^2Sin^2(theta))/n] with the correct integration
*

*> boundaries.
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*>
*

*> The table I am looking for might have entries like this:
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*> sine Vrms = V/.707
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*> Square Vrms = .5*V (If symmetrical around zero axis,
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*> then Vrms = V)
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*> DC Vrms = V
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*> Triangle Vrms = ?*V
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*> Saw Tooth Vrms = ?*V
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*> etc
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*>
*

*> Sorry for any confusion
*

*>
*

*> Doug
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*>
*

*>
*

*>
*

*> Hi Gurus
*

*>
*

*> I am looking for the mathematical formula for RMS voltage. I seem to
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*> remember that it can be expressed as an integral of a squared
*

*> function. I
*

*> can almost fake it(!) but I'd like to see the real thing! I
*

*> would also like
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*> to see a table of RMS values for different types of (non-sinusoidal)
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*> waveforms (such as triangular, saw tooth, etc.) Can anyone
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*> point me to a
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*> web page where this info might exist. Or perhaps, might
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*> someone create the
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*> formula in an equation editor and e-mail it to me as an attachment.
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*>
*

*> Thanks for any help
*

*>
*

*> Doug Brooks
*

*>
*

*>
*

*>
*

*> ***********************************************************
*

*> Doug Brooks' book, "Electrical Engineering for the
*

*> Non-Degreed Engineer is
*

*> now in its 3rd printing. Learn about it at www.ultracad.com
*

*>
*

*>
*

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*> ****
*

*>
*

*>
*

*>
*

*> ***********************************************************
*

*> Doug Brooks' book, "Electrical Engineering for the
*

*> Non-Degreed Engineer is
*

*> now in its 3rd printing. Learn about it at www.ultracad.com
*

*>
*

*>
*

*> **** To unsubscribe from si-list or si-list-digest: send e-mail to
*

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**Next message:**Larry Miller: "RE: [SI-LIST] : RMS Definition"**Previous message:**Doug Brooks: "[SI-LIST] : RMS Definition, clarification"**Maybe in reply to:**Doug Brooks: "[SI-LIST] : RMS Definition, clarification"

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