Maintenance characteristics: AC motors vs DC motors.

• A. AC motors are low-maintenance and rugged; DC motors require regular maintenance due to brush wear.
• B. DC motors are low-maintenance; AC motors require regular maintenance due to bearings.
• C. Both types require equal maintenance.
• D. AC motors are more maintenance-intensive than DC motors.

Answer: (A)

The main point here is that maintenance needs differ because of how the motors are built and how they conduct current. AC motors, especially common brushless induction types, have no brushes or commutators, which are the parts that wear fastest in a motor. Their rugged design and simple moving parts mean they typically require less routine maintenance. DC motors use brushes riding on a commutator to switch current to the windings, and those brushes and the commutator wear over time. This wear can lead to maintenance tasks like inspecting, cleaning, replacing brushes, and possibly truing the commutator, which makes DC motors more maintenance-intensive. Bearings on both types do need periodic attention, but the standout maintenance difference is the brush wear in DC motors. That’s why the statement that AC motors are low-maintenance and rugged while DC motors require regular maintenance due to brush wear best fits the reality of these motor designs.