Early detection of service-induced cracks in turbine generators using ultrasonic techniques

The paper outlines recent developments in ultrasonic techniques and equipment to detect service-induced cracking in the rotating parts of turbine-generators. As examples of the methods employed, three inspections are described in detail. These are for the detection of cracking in alternator pole and winding teeth, in turbine disc bores, and in blade fixing T-slots. The aim in each case is to provide the earliest possible indication of cracking with the minimum of dismantling and re-assembly time