Which arrangement is used to obtain direct current output from a generator?

Which arrangement is used to obtain direct current output from a generator?

• A. Commutator
• B. Slip rings
• C. Brushless induction
• D. PMG

Answer: (A)

To get direct current from a generator, you need a way to keep the output in one direction as the rotor spins. The commutator with brushes provides that. The armature windings generate alternating current as they rotate, but the split-ring commutator reverses the connection of each winding to the external circuit every half turn. Because the contacts switch at the right moment, the current flowing out of the brushes remains in the same polarity, producing direct current (a pulsating DC) at the output. Slip rings, on the other hand, simply pass through the AC from the rotating windings without reversing the connection, so the external circuit sees alternating current. Brushless induction machines produce AC in the stator and rely on separate rectification to get DC, rather than delivering DC directly from the machine itself. A permanent magnet generator typically generates AC and requires rectification to produce DC, rather than providing a DC output directly from the generator’s basic arrangement.

To get direct current from a generator, you need a way to keep the output in one direction as the rotor spins. The commutator with brushes provides that. The armature windings generate alternating current as they rotate, but the split-ring commutator reverses the connection of each winding to the external circuit every half turn. Because the contacts switch at the right moment, the current flowing out of the brushes remains in the same polarity, producing direct current (a pulsating DC) at the output.

Slip rings, on the other hand, simply pass through the AC from the rotating windings without reversing the connection, so the external circuit sees alternating current. Brushless induction machines produce AC in the stator and rely on separate rectification to get DC, rather than delivering DC directly from the machine itself. A permanent magnet generator typically generates AC and requires rectification to produce DC, rather than providing a DC output directly from the generator’s basic arrangement.