Verein Deutscher Ingenieure of Germany evaluated diagnosis and maintenance support for large steam turbines, one of the main elements in power plants. The identification of causes of unbalance-excited vibrations in turbo- machinery and their rapid removement are indispensable for the smooth operation of power plants.

To machine-support this expert task InterFace Computer GmbH in Germany has developed a diagnostic expert system for turbine vibra- tions. When all necessary values such as rotation speed are entered, the system starts inference during plant operation and shows possible steps toward trouble correction. The system, for example, determines whether a turbine blade is missing, or whether a bearing is defective.

Permanent monitoring allows the direct detection of problem sources. Another advantage of early error identification is the prevention of significant secondary damage.

The fault-cause relationships are represented by a set of constraints: attributes of the turbine equipment (like speed of rotation) are inter- connected through constraints. The evaluation mechanism can apply and propagate a constraint "in any direction" on the related attributes, depending on what data is given and what is searched for. The inference mechanism employs a constraint propagation sytem, which is suitable for diagnosis.

Hardware : UNIX Workstation with Graphics Terminal

Software : IF/Prolog�AOSF/Motif

A screen picture of the system