Description and tests of the GENERREX excitation system for large steam turbine-generators

A new excitation system has been developed employing a power source which is an integral part of the generator. Excitation power originates from the generator air-gap flux and from the generator stator winding currents. The physical arrangement of the excitation power source components provides compactness to this self-excited, essentially self-regulated and high initial response system. It facilitates generator maintenance, by eliminating rotating parts from the collector end of the turbine-generator shaft, and simplifies the station layout. The ac excitation power is rectified by means of a full-wave bridge with silicon diodes and shunt silicon controlled rectifiers (thyristors). Extensive use of static components is made in the generator voltage control system coupled with redundant features which permit maintenance during operation.