Describe about Paralleling of D.C Generator

The voltage drop occurs in D.C generator as its load current increases. During parallel operation, any increase of the load taken by one generator and reduce the voltage of that. Higher voltage generator tends to take load from the lower voltage generator. This time higher voltage generator series field strength increases and give higher voltage and load. On the other hand, lower voltage generator, series field strength weakens and reduces its voltage and load. If no correcting factor is used to equal the load, then load swing will continue until one generator has the full load and the other has none. 

 

For this reason, an equalizer which is a low resistance circuit is made between parallel generators via a special bar in the switchboard. It is shown by the dotted line, connecting with the armature ends series field of the two generators. If no.2 generator develops a slightly higher voltage and starts to take more load, then not only its field strength increase, the equaliser passes part of the extra current to the series coil of generator no.1. Then field strength of both generator equal and massive load swing is prevented.

Equaliser contacts in the main breaker are arranged to close before and open after the main contacts.