Helical gearboxes H3 flender pte ltd H3-CH-9-A

Flender/Flender Gear Units/Helical gearboxes H3

d casing) and on bearingtemperature measurement. Probes are commonly used for the monitoring of complete turbo units. Typically gearboxes for the petroleum industry aremonitored with many probes, for protection or for maintenance. Information that is available can detect abnormal operations. With time, the probability failure increases. Troubles in gearboxprotection and maintenance can be due to lack of reliability ofprobes, or trouble in measurement. The power generation industry,on the other hand, uses specification that tends to reduce instru-mentation cost by limiting the number of probes installed on thegearbox. For example, gearboxes between turbines and generatorsare often protected by only thermal probes in sleeve bearings and 9MAINTENANCE AND ONLINE DIAGNOSTICS ON GEARBOXES IN THE PETROCHEMICAL INDUSTRY by Michel Wendling Manager, Client Support Department Flender-Graffenstaden Illkirch-Graffenstaden, France and Edwin Becker Manager, Condition Monitoring Department Flender Service GmbH Herne, Germany thrust bearings with one accelerometer on the casing. Investigation in this case cannot be aided by information from multiple sources,and diagnosis will require the use of portable probes or the use of new temporary probes installed on provisional points that were designed by the gear manufacturer and used for initial shop testing. Vibration Measurements Vibration investigation is probably the best tool to detect the origin of gearbox malfunction, but most monitoring systemsdetect overall vibration values on large frequency band.Unfortunately, gearboxes containing multiple shafts can generate excitations at different frequencies. Each shaft has its own critical speed. Bearings on each shaft can generate fluid film instabilitiesat different frequencies. simple spectrum analysis in low frequency range will indicate the part each shaft plays in the global vibration level and/or detectsubsynchronous instabilities in bearings. In the high frequencyrange, fast F