The Function of the Reaction Rail in the Development of a LIM Propulsion System for Urban Transit

The functional considerations and design parameters which have been taken into account in the development of the reaction rail for a linear induction motor (LIM) are discussed. The LIM, powered by a variable-frequency variable-voltage inverter, is to be applied as the propulsion system for urban transit vehicles. The features that are different in the reaction rail compared with the secondary of a conventional rotary induction motor are greater exposure to environmental conditions, the presence of discontinuities and gaps, and the capability to change air gap, resistance, and magnetic circuits as required. These features are considered from their theoretical and practical aspects. Predicted and test data are given for a number of the alternatives considered.