What method is most commonly used to correct armature reaction in electric motors?

Interpoles are commonly used to correct armature reaction in electric motors due to their effectiveness in counteracting the distortion of the magnetic field caused by the armature current. When a motor operates, the armature current generates its own magnetic field, which can interfere with the main field produced by the stator or field windings. This interference can lead to a loss of efficiency and can cause issues such as sparking at the brushes.

Interpoles are small auxiliary windings placed between the main field windings. They are connected in series with the armature and generate a magnetic field that opposes the distortion caused by the armature reaction. By providing this counteracting field, interpoles help maintain the overall balance of the magnetic field within the motor, improving performance, reducing brush sparking, and ensuring smooth operation.

While other methods like shaded poles and series field connections are used in various applications, they do not specifically address the correction of armature reaction as effectively as interpoles do. Shaded poles are primarily used in single-phase induction motors, and series field connections pertain to different operational characteristics, neither focused on correcting armature reaction specifically.