Subelement C: Components— Topic 21: Transformers
Question 3-21C4
Element 3 (GROL)What is the ratio of the output frequency to the input frequency of a single-phase full-wave rectifier?
Explanation
A single-phase full-wave rectifier converts both the positive and negative halves of an alternating current (AC) input into a pulsating direct current (DC) output of a single polarity.
For every *one* complete cycle of the AC input waveform, which includes one positive and one negative peak, the full-wave rectifier produces *two* distinct output pulses. Both of these pulses are in the same direction (e.g., positive). Therefore, the output waveform completes two "cycles" (or two ripple pulses) for every one cycle of the input AC.
This means that the fundamental frequency component of the ripple in the output voltage is twice the frequency of the input AC. If the input frequency is $f_{in}$, the output ripple frequency is $2f_{in}$. The ratio of output frequency to input frequency is thus 2:1.
Options A (1:1) would be characteristic of a half-wave rectifier, where only one half-cycle is utilized, or simply passing AC through a transformer without rectification. Option B (1:2) is incorrect as the frequency is doubled, not halved.
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