Practical contaminant analysis of lubricating oil in a steam turbine-generator

In order to identify the level of contamination of lubricating oil in a turbine-generator at a local power plant, contaminant analysis was conducted. The contaminant analysis was also used to assess the condition of tribe-components such as bearings, gears and bearing deflectors. Oil samples were taken and the debris in the used lubricating oil were analysed off-line to provide information for the construction of an on-line monitoring system. Statistical analysis of debris was also carried out to determine the quantitative trend of oil contamination. The on-line contaminant monitoring system was then developed with the capabilities to provide an early warning of excessive oil contamination and to detect any impending failures of tribe-components. Guidelines necessary for maintenance engineers such as preset warning level and a trip level (automatic shutdown) of contamination were established. In the system, a device utilizing a filter blockage principle was employed to measure the contamination level. The on-line system developed was installed and field tested in a turbine-generator at a local power plant. During the two year period of investigation, the lubricating system and related tribo-components were revealed to be in normal condition.