Which is a direct conclusion about AC induction motors?

Which is a direct conclusion about AC induction motors?

• A. They are designed for DC power
• B. They are rarely used in aircraft electrical systems
• C. They rely on a rotating magnet only
• D. They have no brushes or armature

Answer: (D)

AC induction motors work by inducing currents in the rotor from a rotating magnetic field produced by the stator. Because the rotor is not connected to the power supply, there are no brushes or armature to wear or spark. The rotating field creates rotor currents, and their interaction with the field produces torque. This leads to the correct takeaway: they have no brushes or armature. The idea they’re designed for DC power is not right because their windings are fed with AC to create the moving magnetic field. The notion that they rely on a rotating magnet only isn’t accurate—the rotating field is produced by the stator, and the rotor itself is driven by induced currents rather than a permanent magnet driving the motion. And in aircraft electrical systems, AC induction motors are commonly used where AC power is available, not rarely.

AC induction motors work by inducing currents in the rotor from a rotating magnetic field produced by the stator. Because the rotor is not connected to the power supply, there are no brushes or armature to wear or spark. The rotating field creates rotor currents, and their interaction with the field produces torque.

This leads to the correct takeaway: they have no brushes or armature. The idea they’re designed for DC power is not right because their windings are fed with AC to create the moving magnetic field. The notion that they rely on a rotating magnet only isn’t accurate—the rotating field is produced by the stator, and the rotor itself is driven by induced currents rather than a permanent magnet driving the motion. And in aircraft electrical systems, AC induction motors are commonly used where AC power is available, not rarely.