Mit Rissen leben - eine sicherheitstechnische Bewertung einer angerissenen Generatorwelle

A generator rotor of an 250 MW oel-power stationgas been cracked due to a short circuit load. In the radial Slots of the rotor 23 cracks are observed by means of visual and dye penetration testing. To decide wehter and for what a time periode the rotor can go in further operation it was necessary to estimate the crack depth and length. This inspection has been conducted using ultrasonic test, dye penetration test and visual inspection using an enoskope. The investigation shows: 1. Cracks with a maximal depth of 50 mm and a maximal length of 150 mm. 2. based on a fracture mechanic analysis and an inservice inspection each year it was possible to operate the cracked rotor for 3 years until the rotor was supplied