Short-circuit forces on turbo-alternator end-windings

A brief review is given of some factors relevant to short-circuit testing of alternators. The forces acting upon the stator conductors, particularly outside the slot, are described and the difficulty of analytical assessment of the damage to insulation is pointed out. Some details are given of the results of test short-circuits on a 60-MW turbo-alternator and also of tests on an experimental replica stator. The degree of correspondence between the short-circuit forces on an alternator and those on such a replica stator is considered in the light of tests carried out to establish this point. A discussion is given of various factors contributing to the severity of short-circuit forces which may occur in service and under present test conditions. The suggestion is advanced that a study of available data concerning actual operational faults be made with a view to obtaining agreement on a more realistic short-circuit test before machines are despatched.