Which statement best describes the role of field pole pieces?

Which statement best describes the role of field pole pieces?

• A. They are used to connect wiring terminals.
• B. They provide cooling to the rotor.
• C. They concentrate the magnetic field in the air gap.
• D. They adjust the rotor speed.

Answer: (C)

Field pole pieces concentrate and shape the magnetic field in the air gap. They’re part of the magnetic circuit and provide a low-reluctance path for flux from one pole to the other, directing it into the small space between the pole face and the rotor. By designing the pole faces and keeping the air gap uniform, they raise the flux density where the rotor conductors cut the field, which strengthens the interaction that produces torque and improves efficiency by reducing stray flux. They don’t serve to connect wiring terminals, cool the rotor, or adjust rotor speed.

Field pole pieces concentrate and shape the magnetic field in the air gap. They’re part of the magnetic circuit and provide a low-reluctance path for flux from one pole to the other, directing it into the small space between the pole face and the rotor. By designing the pole faces and keeping the air gap uniform, they raise the flux density where the rotor conductors cut the field, which strengthens the interaction that produces torque and improves efficiency by reducing stray flux. They don’t serve to connect wiring terminals, cool the rotor, or adjust rotor speed.