Main fans turbo generators
To cool the generator winding, a fan is shrunk-on to the main shaft. The main fan, as a welded unit, must mechanically withstand the highest loads in rated operation as well as during short-term speeds.
The fan is forged in two parts from heat treated steel – US-tested and preprocessed. In the middle of the der Flügel, the Deckscheibe und Nabenscheibe are welded together by constant preheating. The weld seams with a quality of ISO5817-C are cleanly sanded. In order to guarantee the quality of the welding, it is X-rayed before and after heat treatment and magnetic powder is tested. The strength values are checked using a B-sample. The main fan is then balanced to a quality of Q 2.5 and spun at overspeed.