An on-line monitoring system for oil-film, pressure and temperature distributions in large-scale hydro-generator bearings

Instrumentation that allows the behaviour of a hydro-generator thrust beari ng to be monitored during operation is described. The measurement system wa s developed at the Asea Brown Boveri corporate research centre in Switzerla nd and was tested under realistic operating conditions at the Harbin Electr ic Machinery Company bearing-testing facility in the People's Republic of C hina. Newly developed fibre-optical proximity probes were used for the on-l ine monitoring of the thin oil film between the static and rotating parts o f the bearing. These sensors are based on a back-reflection technique and c an be used for various target materials such as Babbitt and Teflon. The mon itoring system comprises about 120 temperature sensors, four pressure senso rs and five optical oil-film thickness sensors. Temperature sensors are ins talled at specific static locations, whereas pressure and oil-film sensors are positioned in the runner and generate data during rotation. A special f eature of the monitoring equipment is its on-line processing capability. Di gital signal processors operating in parallel handle pressure and oil-film thickness data. Important measurement parameters such as the maximum pressu re, maximum temperature and minimum oil-film thickness are displayed on-lin e. Detailed three-dimensional temperature information on one of the load se gments can be obtained from subsequent off-line data analysis. The system a lso calculates two-dimensional plots of the oil-film thickness and pressure for most of the 12 load segments.