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By Clyde V Maughan, Maughan Generator Consultants (retired) This historical perspective on turbine-driven generators, in four parts, is based on Clyde Maughan’s recollections from a 72-year career in turbine/generator design, manufacturing, and service—half that time with General Electric Co, the remainder as an independent consultant. Having joined GE in 1950, and having worked closely with

Stator windings Groundwall insulation. Before the turn into the 20th century, insulating materials were natural products: shellac, cotton, paper. The rudimentary stator-winding designs were at low voltage and low temperatures, and apparently functioned fairly well as long as duties were kept sufficiently low. With inevitable trends to larger generators, with higher voltages and higher thermal

Stator windings Slot support systems. From the beginning, stator bars were held in the slots by wedges of treated paper or hardwood. The electromagnetic forces were low (almost non-existent), the groundwall insulation was soft, and bars had little cause to vibrate. The wedges held the bars in the slots and kept them from falling out

Originally, generators were cooled by once-through open air flow. Contamination problems led to closed ventilation systems, with water-to-air heat exchangers to remove the thermal losses—the TEWAC cooling system (Totally Enclosed Water-to-Air Cooling). This type of system is still very popular for small generators. But by the 1930s, ratings were reaching a size where the ability

The mechanical duties on rotor forgings are extremely demanding on the high-speed generators typically coupled to gas and steam turbines, and great effort has gone into development and optimum application of these forgings. Thus, a few words on this topic are in order here. Rotor body forging The main rotor body forgings reached a crisis

Clearly, this article, presented in the four sections bulleted below, provides a very general overview of generator history, with more left unsaid than said. No doubt there are errors of omission as well as commission. But hopefully the reader has gained a better appreciation for the efforts that went into the generator designs of today.