Q:

What are the necessary requirements for parallel operation of DC generators?

A:

Quick Answer

The parallel connection of the DC generators is done using heavy thick copper bars called bus bars. The positive terminal of the generators needs to be connected to the positive end of the bus bar, while the negative end of the generator should be connected to the negative terminal of the bus bar.

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Full Answer

The paralleling of a DC generator with another DC generator requires that the prime mover of the second generator is taken up to the rated speed first. After the generator begins to run at the rated speed, the field circuit of the second generator switch needs to be closed. The second generator breaker then needs to be closed and the excitation of the generator needs to be varied until it produces a voltage that is equivalent to the voltage on the bus bars. The two generators are now in parallel.

Since the voltage of the generator and across the bus bar are the same, the second generator will not supply any load and is considered to be floating on the bus bars. It is thus required that the generated voltage needs to be more than the bus bar voltage. Raise the field current of the second generator, thus raising the induced electromotive force. It allows the second generator to supply the appropriate load.

Vary the field excitation to shift the load from one DC generator to the other. When the load on the first generator exceeds the rated capacity, the second generator begins to operate.

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