Innovative robotic technology for monitoring the integrity of generator retaining rings

The synchronous generator is a primary component of a power plant, requiring periodic inspection to reduce the risk of costly forced outages. The generator retaining rings are a highly stressed component and subject to particular attention, as they play a vital role in securing the generator rotor windings against centrifugal forces during operation. The typical condition assessment regime relies on the generator retaining rings being removed to enable inspection of the inside surfaces for damage. This process necessitates a significant human effort and is time consuming, resulting in major down time costs for the power plant operator. This paper describes an automated robotic scanner dedicated to ultrasonic and eddy current inspection of the retaining rings while they are mounted and the generator rotor remains in place within the generator stator. The scanner described here features a light weight frame and minimized dimensions, making it suitable for a wide range of generator configurations.