The detection of lubricating oil viscosity changes in gearbox transmission systems driven by sensorless variable speed drives using electrical supply parameters

Abstract

Abstract. Lubrication oil plays a decisive role to maintain a reliable and efficient operation of gear transmissions. Many offline methods have been developed to monitor the quality of lubricating oils. This work focus on developing a novel online method to diagnose oil degradation based on the measurements from power supply system to the gearbox. Experimental studies based on an 10kW industrial gearbox fed by a sensorless variable speed drive (VSD) shows that measurable changes in both static power and dynamic behaviour are different with lube oils tested. Therefore, it is feasible to use the static power feature to indicate viscosity changes at low and moderate operating speeds. In the meantime, the dynamic feature can separate viscosity changes for all different tested cases.

Monitoring gearbox oil viscosity by means of motor current signal analysis

“…The condition monitoring technique presented in this paper originated from practical data obtained in a realistic laboratory test bench (8) . Consequently the point of departure of the discussion in this paper is a brief description of the laboratory test bench used to generate the data.…”

“…Oil EP 650 was obtained by mixing 39% of EP 100 with 61% of EP 1000. More details on the experimental procedure can be found in (8) .…”

“…This assertion is supported by the results obtained from the test bench. As part of the data gathering process performed in (8) the absolute dynamic viscosity of each oil type was measured at different discrete temperatures. These measurements are shown in figure 2.…”

“…In MCSA a variety of spectral analysis techniques are applied to the motor stator current signals in order to detect the state of health of the load. MCSA was also used in previous work to monitor the viscosity of gearbox oil (8) . In (8) , the power (and change in power) of specific sidebands of the shaft frequency were used to monitor the gearbox oil.…”

“…MCSA was also used in previous work to monitor the viscosity of gearbox oil (8) . In (8) , the power (and change in power) of specific sidebands of the shaft frequency were used to monitor the gearbox oil. Sideband frequencies in the current spectrum can however be influenced by other potential problems in the electromechanical system ranging from bearing faults (9) to gearbox teeth damage (10) .…”