Which motor type typically has higher maintenance due to brushes and commutator wear?

Which motor type typically has higher maintenance due to brushes and commutator wear?

• A. AC motors
• B. DC motors
• C. Induction motors
• D. Synchronous motors

Answer: (B)

Direct-current motors rely on a mechanical commutator and carbon brushes that stay in contact with the rotating winding to switch current as the rotor turns. This sliding contact inevitably wears the brushes and the commutator surface, leading to changes in contact quality, sparking, heat, and insulation wear. Because of that, these motors require regular inspection and replacement of brushes, possible commutator resurfacing, and more frequent maintenance overall. In contrast, induction motors and most synchronous motors operate without the rotor having sliding electrical contacts, so they are brushless in normal operation and require less routine maintenance for wear on electrical contacts. (Note that some AC devices called universal motors do use brushes, but that’s a special case.)

Direct-current motors rely on a mechanical commutator and carbon brushes that stay in contact with the rotating winding to switch current as the rotor turns. This sliding contact inevitably wears the brushes and the commutator surface, leading to changes in contact quality, sparking, heat, and insulation wear. Because of that, these motors require regular inspection and replacement of brushes, possible commutator resurfacing, and more frequent maintenance overall. In contrast, induction motors and most synchronous motors operate without the rotor having sliding electrical contacts, so they are brushless in normal operation and require less routine maintenance for wear on electrical contacts. (Note that some AC devices called universal motors do use brushes, but that’s a special case.)