Robotic crawler for inspecting generators with very narrow air gaps

The non-destructive inspection of generator stators is a repetitive and cost-intensive task. For some types with very small entrance gaps (around 9 mm height), it was even necessary to always remove the rotor. This paper describes the design and prototype implementation of a new robotic crawler which is only 8 mm high and thus can inspect all types of generators with the rotor installed. Different solutions of how to realize torque transmission and attraction forces at such a small size are discussed, as well as the design of magnetic guiding wheels with a mechanism to fold them when passing the narrow entrance gap. The paper concludes with some test results - both in an artificial test environment and in real generators - and provides an outlook on future improvements of the prototype.