Although unbalanced magnetic pull can affect other rotating electric machines such as DC motors and generators and single-phase motors and generators, our focus in this article will be on three-phase squirrel cage induction motors. The two main topics are unbalanced magnetic pull (UMP) and rotor pullover.

Aunque la tracción magnética desbalanceada puede afectar a otras máquinas eléctricas rotativas, como los motores y generadores de CC y monofásicos, nuestro enfoque en este artículo se centrará en los motores jaula de ardilla trifásicos. Los dos temas principales son: La tracción magnética desequilibrada (UMP) y el descentrado del rotor (pullover).

The physical air gap between the rotor or armature and the stator or field frame is complex and plays a critical role in the performance of AC and DC machines. Most repairers do not realize how little they understand about this subject.

Air gap is the physical gap between a rotor and stator core in an AC machine, or between the armature and fields / interpoles in a DC machine. The role of the air gap is not as simple as it appears.

Topics discussed in this article include:

• Important principles (magnetic force and the amount of current to drive flux through air)
• Air gap in AC machines
• Air gap in DC machines