which is the most commonly quoted, average, peak, peak to peak or RMS? when talking about ac voltage and why?

Answer 1

RMS is because it is the effective use able voltage of the sin wave. Basically RMS is peak voltage times .707. This represents what the voltage would be if it were DC. Or another way to look at it is that its the usable voltage that comes out of of an AC power source. The peak voltage coming out of your wall outlet (assuming USA) is 170VAC when you multiply that .707 you get somewhere around 120v because that is the usable voltage by your appliances.

The reason it is most common is because it is the actual use able voltage. The appliance can not use the whole 170VAC because it is only available for 1/60th of a second.

Answer 2

They all have their purpose. RMS is used to determine power delivered to load. RMS = root mean square. It is determined by squaring, then taking the mean, then taking the square root. It is similar to an average, but the squaring makes everything positive since the true average of a sinewave is zero. The RMS voltage of a wall outlet in the USA is 120 V. Peak is more often referred to as zero to peak and is the amplitude of the sine wave. 170 V at the wall. Peak to peak is the trough to the peak of a sine wave and is 340 Volts. In electrical engineering, zero to peak gives the amplitude of the sine wave and peak to peak gives twice the amplitude. Essentially, is allows the user to determine if there is symmetry or not which is a tool to determine if an amplifier is designed properly.

Answer 3

The RMS voltage of AC reguardless of waveform will illuminate light bulbs and deliver the same heat output from appliances as DC of the same voltage. So 120 volts of DC is the work equivalent of 120 volts RMS AC. Calorimetric voltmeters use the heat generated by the AC waveform, and they are calibrated using an equivalent DC test voltage.

Answer 4

Usually RMS voltage is quoted because it is more representative of the true value of the voltage.