EXPERIMENTAL RESULTS OF DIFFERENT OIL CONDITION MONITORING APPROACHES FOR WIND TURBINE GEARBOXES IN AN OIL SENSOR TEST BENCH

摘要

The results of this study show that the temperature measurements of some oil sensors are strongly influenced by the ambient temperature due to the positioning of their temperature sensing element within the sensor body. A useful oil-temperature measurement requires that the temperature sensing element is in contact with the oil. According to the results of the saturation measurements, the horizontal oil-properties sensor showed a difference on the water content measurements around 5% points of saturation in comparison with the moisture sensors and the oil-properties sensor in the vertical pipe. From the tests, it was concluded that this difference in the measurements is not related to the orientation or the measurement principle of the sensor, rather to the individual sensor. A high precision in the output signal of the saturation measurements of all sensors was verified by repeating the test profiles obtaining a maximum deviation of 0.5% points of saturation. However to validate the accuracy of the saturation measurements, references values are still required. The water measurements by means of Karl-Fischer-Titration and the measurements of online saturation measurements indicate that the oil aging can have an influence in the capacity of the oil to get saturated. The test with particle-contaminated oil shows that for particle counting with wear-debris sensors, the positioning of the sensor can have a strong influence on the particles circulating through the sensor due to high settling velocity of the particles with sizes of >100um. This observation and the results of the offline oil analysis suggest the conclusion that wear debris in a wind turbine gearbox is detectable by means of particle counters only for a short period after debris generation and might not be detectable by means of offline oil analysis.