Which type of connection allows the DC series generator to function correctly?

The correct answer is that a series connection allows the DC series generator to function correctly. In a DC series generator, the field windings are connected in series with the armature winding. This design means that the same current flowing through the armature also flows through the field windings. Consequently, as the generator produces more current, the magnetic field strength increases proportionally, which leads to higher voltage output.

This relationship between the field strength and the armature current is essential for the generator's operation. The series connection ensures that as load increases, the generator can provide more power due to the enhancement of the magnetic field, which directly boosts its output voltage. This characteristic is particularly useful in applications requiring high starting torque or where current demand may vary significantly.

In contrast, a parallel connection would not allow the necessary interaction between the armature and field windings in a series generator. A shunt connection would create a different operating principle, which is not suitable for a series generator, and an open connection would prevent the generator from functioning at all, as there would be no flow of current. Thus, the series connection is the only configuration that enables the DC series generator to operate effectively.