ANALYSIS OF CAPACITIVE EFFECT AND LIFE ESTIMATION OF HYDRODYNAMIC JOURNAL BEARINGS ON REPEATED STARTS AND STOPS OF A MACHINE OPERATING UNDER THE INFLUENCE OF SHAFT VOLTAGES

A theoretical analysis has been carried out to study the capacitive ef fect and life estimation of hydrodynamic journal bearings on repeated starts and stops of a machine operating under the influence of shaft v oltages. The analysis gives the time required for the charge accumulat ion and increase of charge with time on the liner surface of a journal bearing based on bearing capacitance, resistance of film thickness, a nd the shaft voltage. Also, it investigates the effect of gradual leak age of the accumulated charges with time as the shaft voltage falls wh en the power supply to the machine is switched off. This paper gives a n approach to determine the rates of the number of shaft revolutions r equired for charge accumulation and gradual discharge of the accumulat ed charges on the liner surface of a bearing depending on bearing-to-s haft voltage. Also, the number of repeated starts and stops before ini tiation of craters on the liner surface of a hydrodynamic journal bear ing is established to restrict deterioration and damage of the liner. The diagnosis has the potential to study the transient effect of the s haft voltages on a journal bearing during the start and stop cycle of a machine.