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Case Analysis of Oil Pressure Sensor Failure of Diesel Generator Sets

May 17, 2022
At present, the functional requirements of diesel generator sets are getting higher and higher, and the role of temperature and oil pressure sensors is becoming more and more important. If used or selected improperly, it may cause a lot of trouble because of a small sensor. The function of the oil pressure sensor is to monitor the amount of lubricating oil used by the generator set at any time. If the lubricating oil is less, the wear of the generator set will increase, resulting in a reduction in the service life of the diesel generator set. This article JUNVOCH shares a case analysis of diesel generator oil pressure sensor failure.
Customer repair case:
The user operates the diesel generator set according to the normal operation steps, and it can start to run. The oil pressure, oil temperature, water temperature, speed, etc. are all normal during no-load operation. It will automatically stop, and at the same time low oil pressure sound and light alarm. After the automatic shutdown, start the diesel engine of the diesel generator set again. When the speed reaches the rated speed, the low oil pressure sound and light alarm will appear and automatically stop.
Failure analysis: From the phenomenon, the cause of the failure is the low lubricating oil pressure. Generally speaking, the reasons for the low lubricating oil pressure of the diesel engine of the diesel generator set are the damage of the pressure gauge due to the low lubricating oil viscosity, the blockage of the oil Fleetguard filter, the oil pump not pumping oil, and the bearing clearance being too large.
1. Check the lubrication system according to the principle from simple to complex. First of all, based on the fact that the diesel generator set lubricating oil has been used for a long time, the special lubricating oil is replaced according to the requirements, the test machine is run for about 1 hour, the diesel generator set automatically stops again, and the fault remains the same. After shutdown, check the viscosity of the lubricating oil and whether there is any leakage of lubricating oil on the machine. After inspection, the viscosity of the lubricating oil is qualified and there is no leakage of lubricating oil on the machine.
 2. Check the lubricating oil pressure. Since the lubricating oil pressure detection of the diesel generator set uses a pressure sensor to convert the lubricating oil pressure into resistance and output it to the instrument and electronic control system, install a straight-through oil pressure gauge on the diesel engine of the diesel generator set, and start the engine. Run the unit. The lubricating oil pressure is closely monitored during the entire operating phase of the diesel generator set. After running for about 1 hour, the diesel generator set will automatically stop again. Observe the external pressure gauge indicating that the oil pressure is normal. At this point, it can be concluded that there is no problem with the oil pressure of the machine. The problem should be the oil pressure sensor. Put on a new pressure sensor, start the machine, and the machine does not stop automatically after 2 hours of operation, and the fault is eliminated.
Technical summary: When the machine is running for about 1h, the sensor has a problem, which may be due to the increase in oil temperature after the diesel generator set is running. When the temperature is high, the working curve of the sensor changes due to the long-term performance degradation, and a false alarm occurs; after the machine cools down, the sensor returns to normal, so the fault occurs when the machine runs normally when the machine is cold, and automatically stops after the machine is warmed up.