Development of a 300 kW 3000 rev/min d.c. machine using thyristor-assisted commutation

The principle of thyristor-assisted commutation was easily demonstrated on small laboratory-type machines, but the commercial significance of the concept could only be investigated by constructing a machine of a size where commutation would normally be a problem. A 300 kW, 3000 rev/min version was built and the performance of this prototype is described. In particular, it is explained how the problematic sliding-contact performance of this type of machine was satisfactorily achieved using (eventually) only commutators and brushgear of conventional construction. Companion papers describe the commutating-time calculations and the terminal characteristics of the machine.