Experinece And Recent Development With Gas Directly Cooled Rotors For Large Steam Turbine Generators

As recently as ten years ago, projections of ever increasing unit ratings spurred development efforts toward improved cooling systems for generator rotors. Today, however, the concern of the power generation industry is focused on reliability and efficiency rather than on rating growth. Consistent with these concerns, gas- cooled two-pole rotors with diagonal flow ventilation and gas- cooled four-pole rotors with radial flow ventilation have provided reliable and efficient performance. In addition, development programs set in motion in the early 70' s, prior to the reduction in projected unit ratings, have demonstrated that further improvements in efficiency, as well as rotor thermal capability, can be attained with gas-cooled rotors. This proven capability will provide for the needs of the power generation industry both today and in the foreseeable future.