Ripple

In the electrical science, ripple refers to the small unnecessary residual periodic difference of the  DC or direct current output of  the power  distribution  that has been  produced from the  AC  or alternating current source. The pulsations or ripple caused by the ac components in the rectifier output are undesirable in the supply. The amount of ripple compared with direct component is a measure of purity of rectifier output and is called Ripple factor. It is defined as follows:

Ripple Factor = Effective value of all ac components/ Average component

Single-pulse Waveform    Ripple factor = 1.21(121%) Two-pulse Waveform      Ripple factor = 0.48 (48%) Six-pulse Waveform        Ripple factor = 0.13 (13%) Twelve-pulse Waveform Ripple factor = 0.03 (3%) Multi-pulse Waveform or DC Ripple factor = 0 (0%) We will discuss these circuits and their working. The major components are:

• High tension transformer
• Filament transformer
• High tension rectifiers
• Two tube connection
• HT Cables and Plugs
• Filament circuit
• Protection of X-ray tube
• Timer
• Mains compensation

It is seen that the output of half wave rectifier is not pure DC but a pulsating DC. The output contains pulsating components called ripples. Ideally there should not be any ripples in the rectifier output. The measure of such ripples present in the output is with the help of a factor called ripple factor denoted by y. It tells how smooth the output is. Smaller the ripple factor closer is the output to a pure DC. The ripple factor expresses how much successful the circuit is, in obtaining pure DC from AC input.

                       R.M.S. value of AC component of output
Ripple factor γ =   ________________________________________
                       Average or DC component of output

Mathematically ripple factor is defined as the ratio of R.M.S. value of the AC component in the output to the average or DC component present in the output.

Questionnaire:

• What is ripple? Explain?