Significance of 3 Phase Rectifier

A SINGLE phase rectifier also rectifies i.e. converts AC SUPPLY to DC supply but uses only single phase of transformer secondary coil for the conversion. And the DIODES are connected to the secondary winding of single phase transformer.

The drawback of this arrangement is high ripple factor. In case of half wave rectifier the ripple factor is 1.21and in case of full wave rectifier the ripple factor is 0.482. In both the cases the value of ripple factor cannot be neglected. While in case of half wave rectifier the value is quite large but in full wave rectifier too the value of rectifier is significantly large.

Thus, in such types of arrangement we need smoothing circuit in order to remove these ripples. These ripples are the AC components in the DC voltage. This is called pulsating DC voltage. If this pulsating DC voltage is used in several applications it lead to POOR performance of the device. Thus, the Smoothing circuit is used, filter works as a smoothing circuit for rectifier system.

But after this smoothing process the rectifier voltage falls to zero at some point. Therefore, if in place of single phase transformer we use three phase transformer the ripple factor can be reduced up to a large extent. One of the significant advantage of three phase transformer is that the rectified voltage do not falls to zero EVEN when no smoothing arrangement is used