Question 15.8: An AC sine wave with an RMS value of 120 V is connected to a......
An AC sine wave with an RMS value of 120 V is connected to a full-wave rectifier. What is the average DC voltage?
The problem can be solved in one of two ways. The RMS value can be changed into peak and then the peak value can be changed to the average value:
peak = RMS × 1.414
peak = 120 V× 1.414
peak = 169.68 V
average = peak × 0.637
average = 169.68 V × 0.637
average =108.086 V
The second method of determining the average value is to multiply the RMS value by 0.9:
average = RMS × 0.9
average = 120 V × 0.9
average =108 V
The conversion factors given are for full-wave rectification. If a half-wave rectifier is used (Figure 15–15), only one-half of the AC waveform is converted into DC. To determine the average voltage for a half-wave rectifier, multiply the peak value by 0.637 or the RMS value by 0.9 and then divide the product by 2. Because only half of the AC waveform has been converted into DC, the average voltage will be only half that of a full-wave rectifier (Figure 15–16).
