Brushless exciter fault indicator system

In a synchronous dynamoelectric machine with brushless excitation, the combination comprising:

• a main machine rotor member having field coils connected together to form a main rotor field winding, an alternating current exciter having a stator field member and a plurality of salient stator poles thereon, stator field coils disposed on said salient poles and connected together to form a stator exciter field winding, an exciter armature member rotatable with said main rotor field winding and having an armature winding thereon, said exciter armature winding being coupled magnetically with said exciter stator field winding for developing an alternating current excitation signal within said armature winding, rectifier means interconnecting said exciter armature winding and said main rotor field winding to provide direct current excitation to said main rotor field winding, said rectifier means being rotatable with said armature, a sensing coil disposed around a selected one of said salient stator poles of said exciter for developing an alternating electrical signal in response to changes in the magnetic flux wave linking said rotating exciter armature member and the field coil of said selected salient pole, including changes due to faults in said armature winding and in said rectifier means, and means connected to said sensing coil to indicate variations in said alternating electrical signal.