Abstract: A protective circuit is provided for a brushless excitation system using a rotating rectifier assembly to supply field excitation to a synchronous generator. A thyristor is connected across the generator field winding and made conductive when the field winding voltage exceeds a preset level to shunt the field winding and protect the rectifier diodes against high reverse voltages.

Abstract: A method and apparatus are provided for detecting rotor faults in large dynamoelectric machines, such as turbine generators. Faults in the rotor windings of such machines may occur as shorted turns or as ground faults, and in either case even harmonics are produced in the field flux waveform in the air gap of the machine. The occurrence of such faults, therefore, can be detected by monitoring the flux waveform in the air gap to detect the presence of even harmonics. This may be done by means of a search coil or coils properly disposed in the air gap of the machine.

Abstract: A winding conductor is provided for large dynamoelectric machines, such as turbine generators, consisting of two parallel bars each comprising two stacks of strands transposed between the stacks. The radial flux in the machine causes circulating currents with unequal distribution of current between the two parallel bars of such a conductor, causing excessive heating in one of the bars. The two bars of each conductor are, therefore, made of different cross-sectional areas substantially proportional to the different currents, so that in normal operation, the current density is the same in both bars and overheating is prevented.