Transient performance of eddy-current couplings

Eddy-current couplings are normally used in conjunction with control systems, yet no transient theory for this machine has previously been published. The constant-slip transient performance is calculated from thedesign information, without using experimental data, and is shown to give good results on a test machine. The damping effects of the solid-iron loss member are shown to be negligible over a wide range of slip speed, so that the main timer constants are associated with the field member, which are easily calculated using standard design methods. Test values of load-flux distribution under transient conditions are given. The effectof the index used to represent the magnetisation curve and of the approximation for flux level at various speeds is discussed. The use of the method to calculate large torque transients at low slips and for incremental voltage steps on the field are briefly described.