The nature of voltage ripple on D-C generators

THE output voltage of a d-c generator contains an a-c component which is superimposed upon the d-c output of the generator. This voltage component, or voltage ripple, may be less than 1 per cent of the output voltage or may have peaks as high as 10 per cent of the d-c output, depending upon the design and condition of the generator. For many applications of d-c power the voltage ripple is of no consequence and may be neglected; however, there are other applications, such as some types of electronic equipment where d-c power of high purity is essential. In these cases the voltage ripple must be reduced to a low value either by design of the generator, filtering of the output, or both. Where the voltage ripple is to be reduced by filtering, it is desirable to know the magnitude and frequency of the various components that make up the voltage ripple. If the ripple is to be reduced by design of the generator, it is necessary to know the cause of each of the ripple-voltage components.