Mathematical Analysis of Double Line-to-Ground Short Circuit of an Alternator

The performance equations of ac machines referring to the α and β axes developed in a previous paper[1] are used to study the case of a double line-to-ground short circuit of a salient pole synchronous machine. Significant corrections are offered to the solutions proposed by other authors pertaining to the same case. Mathematical proof is established for such rectifications. As a result, new expressions for armature currents and field current are developed. In addition, decrement factors and a simple formula for X2 are derived.