RMS Calculations

by Brad Suppanz

Some typical periodic power supply waveforms are shown below.

Below is a live web calculator that you can use to find the RMS, DC, and AC components of waveforms. Just enter the values to desribe a waveform based on the figures above.

Enter V1 or I1:
Enter V2 or I2:
Enter the duty cycle, D: (where D is between 0 and 1)

(a) Pulse Waveform:
RMS = V1*SQRT(D) =
DC = D*V1 =
AC = SQRT(RMS^2 - DC^2) =

(b) Triangle Waveform:
RMS = SQRT((I1^2 + I1*I2 + I2^2)/3) =
DC = (I1 + I2)/2 =
AC = SQRT(RMS^2 - DC^2) =

(c) Trapezoidal Waveform:
RMS = SQRT(D*(I1^2 + I1*I2 + I2^2)/3) =
DC = D*(I1 + I2)/2 =
AC = SQRT(RMS^2 - DC^2) =

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Copyright 1997 Brad Suppanz. All rights reserved.
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Written 12/16/97
Last updated 7/20/2004
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