Use of Magnetic Circuits in Leakage Reactance Calculations

The stator and rotor currents are primarily a function of the leakage reactances of the machine. In particular, key performance characteristics such as breakdown torque, starting torque, and inrush current are nearly independent of magnetizing inductance but depend critically upon the leakage inductances. In addition, the key electromagnetic time constants are dependent almost solely upon the leakage inductances of the machine. Five principle components of leakage flux can be identified for induction machines. These are slot leakage flux; end‐winding leakage flux; harmonic or belt leakage flux; zigzag leakage flux; and skew leakage flux. The leakage flux distribution in a practical machine is clearly a three‐dimensional problem. The flux which is forced across a slot is driven by the current which flows in the slot itself. By Ampere's law, the MMF supplied by the current in the slot is consumed by an MMF drop in the iron plus the drop in air across the slot.