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| Where is mean voltage used? |
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| mustafayilmaz:
I know what RMS voltage is. RMS sine voltage does the same job as dc voltage. In full wave rectifier circuits there is something called average dc voltage. Its formula is 0.6366*Vpeak. I don't understand what this means. Where is this formula used? I have a guess; What would sine voltage be like if it were a straight line? Why do we need average voltage when there is rms voltage? Does average voltage represent pure dc voltage? (0V ripple) |
| ebastler:
The average voltage is what you can measure relatively easily, by sending the signal through an integrator or low-pass filter. |
| retiredfeline:
Mean voltage is when you don't want kind voltage. :-DD |
| ebastler:
--- Quote from: retiredfeline on November 09, 2023, 01:10:20 pm ---Mean voltage is when you don't want kind voltage. :-DD --- End quote --- Yeah, anything above 100V or so can get pretty mean. ;) |
| TimFox:
Mean or average voltage: some voltmeters, especially older analog units, measure the mean absolute value (average of the full-wave rectified signal), but the display is calibrated for RMS voltage. Just as the mean is 0.6366 x Vpeak, the RMS is 0.707 x Vpeak. Therefore, the scale factor between them is VRMS = 1.11 x Vavg. -hp- was careful to label the meter "average responding" for such circuits, even though the calibration was RMS. Note that these values apply to a sine-wave input. For DC or a square wave, Vpeak = Vavg = VRMS. The diagram posted above is an ideal rectifier, where the op amps eliminate the voltage drop across the diodes to produce the waveforms shown; the filter extracts the mean voltage of the FW rectified waveform. Another place where mean voltage appears: in an old-fashioned "choke-input" filter after a rectifier, the rectified waveform goes through a large inductor to a capacitor. Neglecting losses in the inductor, for a sufficiently large current, the output voltage is the mean voltage (as discussed above) with a ripple voltage. For small currents, the inductance is insufficient and the output voltage approaches the peak voltage (as in a capacitor-only filter). |
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