Electrical Engineering XYZ MCQs
The EMF induced in the dc generator armature winding is:
- AC
- DC
- Both of these
- None of the above
Correct answer: 1. AC
Explanation: In a DC generator, as the armature rotates within the magnetic field, it indeed induces an alternating current (AC) in the armature winding. This induced AC occurs due to the changing magnetic flux through the armature coils as they rotate. The direction of the induced current changes with each half-rotation of the armature.
However, the function of the commutator is to convert this induced AC into direct current (DC). The commutator, which consists of a set of split metal rings with brushes contacting them, ensures that the current produced in the armature always flows in the same direction in the external circuit. It does this by reversing the connections to the external circuit at the precise moment when the induced current changes direction in the armature winding. This process effectively converts the induced AC into DC.
So, while the induced EMF in the armature winding is AC, it is converted to DC by the commutator mechanism.