Parallel Operation of Compound DC Generators

As Compound generators undergoes drooping characteristic, hence it is possible to operate them in parallel without any difficulty. Below figure shows the parallel conection of compound generator. Any increase in the load current in one generator strengthens the field flux, and hence increases the generator voltage. It causes the generator to take up still greater load. If the load is fixed in some case, the other generator sheds part of its load, which results in the weakening of its field and it sheds more load. If this process is continued cumulatively, one generator can run the entire load and it can drive the other as a differentially compounded motor at an excessively high speed.

Stable the DC Compound Generator in parallel

To get stable operation of compounded generators in parallel, the series field windings are connected in paralled using equalizers that are low-resistance connections. These are usually provided in the form of another bus bar on the switch board.