Scale-model linear induction motors

As an alternative to analysis, the principle of electromagnetic similitude is applied to linear induction motors. It is shown that exact similitude is not essential. Shadow windings are introduced as a means of determining power, impedance and voltage levels under constant-current conditions. Hence the constant-voltage performance of the device can be derived. Results obtained for both static and dynamic thrust, for real and scale-model machines, are compared. It is concluded that scale-modelling techniques can give an accurate indication of all the electromagnetic forces in l.i.m.s. Finally, an index of l.i.m.s is proposed, expressed in terms of dimensionless parameters.