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The application of active magnetic bearings for rotating machinery has become state of the art and ranges from research prototypes to industrial applications, from small turbo-molecular pumps to powerful pipeline compressors in the megawatt range. Users are aware that, beyond function, the safety and reliability of this equipment is critical to its continued commercial development. Safety is more than a mere technical issue. It contains a strong component of psychological interpretation, and societal demands for safety in machinery are ever increasing. Reliability, on the other side, has a definitely technical touch, and it appears to be more amenable to engineering calculations and to economic considerations. Mathematical tools for assessing reliability of classical technical systems, and performance numbers for comparing them, such as mean time between failures, are readily available. The reliability analysis of given technical structures and systems, consisting of a more or less large number of classical components, is rather well developed [33]. However, the active magnetic bearing is not a classical technical system. It is a typical mechatronic product, and as such it contains information processing components, software and feedback loops. For such components, in particular for software, reliability analysis is still under development. In addition, the synthesis of a safe mechatronic system, the method of designing it, is not structured in a systematic way. There is a strong opportunity, however, to make mechatronic systems, despite their obvious complexity, more reliable than classical ones. It is the potential of internal information processing, somehow resembling the ability of living beings to use information to increase their chances of ‘survival’, which could make mechatronic systems more reliable. This chapter will, firstly, address conceptual questions of safety and reliability, in particular, stating that it is theoretically not possible to build a fully safe system. Philosophical reasoning on the logic of science shows that safety can only be improved, step by step: it cannot be guaranteed. Subsequently, the main emphasis is put on the technical side of safety and reliability for AMB/rotor systems. Section 18.3 will give a survey on failure examples in mechatronic systems and AMBs. In Sect. 18.4, means for reducing the |
