Form Factor | Ripple Factor

Form Factor Definition

Form factor (FF) of a waveform is defined as the ratio of, rms value of waveform, to the, average value of the waveform.

Qualitatively, FF value gives idea about the smoothness of the waveform i.e as FF decreases and approaches 1 , smoothness of waveform improves towards pure dc.

Since, rms value ≥ average value of a waveform , therefore, FF ≥ 1

Form Factor of Sine wave

Let v=V_m sinwt be the sine wave.

Form Factor of Pure DC

Let, i=I_o ,be pure (constant) dc. Therefore, its rms value = its average value = I_o

Hence, FF = 1

Ripple Factor Definition

Ripple factor (RF) of a waveform is defined as the ratio of, rms value of ac component of waveform, to the, average value of the waveform.

Qualitatively, RF value gives idea about the amount of harmonics present in the dc waveform.

Therefore, RF is a very important merit in deciding the effectiveness of a rectifier. The smaller the RF, the lesser is the ac component present , hence, more effective is the rectifier.

As the ac component in a waveform decreases, the rms value of ac component decreases and hence, RF decreases. Thus, as RF decreases towards zero, the dc waveform harmonics reduces towards zero.

RF=0 for pure dc.