柴油发电机组油雾保护系统常见故障及对策：
1、元件老化，温度漂移等引起灵敏度改变
结合电厂的实际并经有关专家同意，将报警阀值S开关调至第4级（原4台机组均在第3级），运行至今未发生跳机现象。
2、电子板故障
当油雾探测器出现红、绿指示灯全部熄灭的现象，且检查24VDC电源正常、插头无松动时，基本上就可判断为电子板故障，也可以采用对换其它柴油发电机组的电子板来进行判断。如确属电子板故障，就应该及时检修或更换。
3、曲轴箱油气中含有大量的水分
由于水分的存在，使得测量通道内的不透明度大大增加，致使电子装置发生误报。这就需要检查润滑油中是否含有水分、润滑油冷却器是否泄漏、空气系统是否过度潮湿及油雾探测器底板内的加热器是否工作正常等。近几年来，通过对高油雾跳机事件的分析发现，真正高油雾跳机为0%，高水份跳机为98%（而且最后检查，95%都是因润滑油冷却器的泄漏引起的），其余故障为2%（如电子板故障、继电器误动等）。所以如果在润滑油进机管道上加装一套高灵敏度的水份检测装置用于报警，就可以在水份过高时及时提醒运行人员，降低具有破坏性的跳机次数，增加电网的稳定性。
4、装设油雾探测器装置的根本目的是监测柴油机本身曲轴箱内部的工作状况是否发生变化。比如活塞环失效（包括剥落、异常磨耗、折断）造成缸套漏气到曲轴箱，形成高油雾。这时要检查缸套及活塞环，损坏的要更换。又如主轴瓦或连杆轴瓦高温烧瓦造成局部高温，造成油雾浓度增大而停机时，要打开防爆人孔门，仔细检查连杆大端轴承及轴是否有烧伤，必要时更换。
5、油雾探测器本身的故障类型比较多，这些故障虽不会引起跳机，却会使柴油机失去重要的保护。根据运行经验总结，只要做到以下几点，就可将故障率降低到最低，也可使误跳率大大降低，并为跳机后的检查提供第一手资料。
⑴维护人员应做好定期维护。定期更换空气滤片、减压空气滤片，排出冷凝管的水分，清洗阀箱的油污，用酒精清洗红外探头，用压缩空气吹扫采样管、油路、气路，并做必要的报警试验及高油雾保护动作（最简单的方法是从采样管入口处吹一口香烟的烟雾进去）试验。
⑵发电机组运行时，运行人员应认真监测轴承温度、润滑油温度等有关参数，并定时观察油雾探测器工作状况、油雾浓度的指示情况、曲轴箱U形差压计的差值、曲轴箱透气装置有无冒烟、曲轴箱防爆门是否烫手、曲轴箱高压差有无报警等。如发生高油雾跳机应尽快记录浓度值、阀箱翻牌情况、曲轴箱差压计的差值、轴承温度有无异常及油雾探测器各指示灯的指示情况等。
Common faults and countermeasures of oil mist protection system for diesel generator set:
1. Sensitivity changes caused by component aging, temperature drift, etc
Based on the actual situation of the power plant and with the consent of relevant experts, the alarm threshold S switch was adjusted to level 4 (the original 4 units were all at level 3), and no tripping phenomenon has occurred since operation.
2. Electronic board malfunction
When the red and green indicator lights of the oil mist detector are all turned off, and the 24VDC power supply is checked to be normal and the plug is not loose, it can basically be judged as an electronic board fault. It can also be judged by swapping the electronic board of other diesel generator sets. If it is indeed an electronic board malfunction, it should be promptly repaired or replaced.
3. The crankcase oil and gas contain a large amount of moisture
Due to the presence of moisture, the opacity in the measurement channel greatly increases, leading to false alarms in electronic devices. This requires checking whether the lubricating oil contains moisture, whether the lubricating oil cooler leaks, whether the air system is excessively humid, and whether the heater inside the bottom plate of the oil mist detector is working properly. In recent years, through analysis of high oil mist tripping events, it has been found that the true high oil mist tripping rate is 0%, high moisture tripping rate is 98% (and final inspection shows that 95% is caused by leakage of lubricating oil coolers), and the remaining faults are 2% (such as electronic board faults, relay misoperation, etc.). So if a high-sensitivity moisture detection device is installed on the lubricating oil inlet pipeline for alarm, it can timely remind the operators when the moisture is too high, reduce the number of destructive trips, and increase the stability of the power grid.
4. The fundamental purpose of installing an oil mist detector device is to monitor whether the working condition inside the crankcase of the diesel engine itself has changed. For example, piston ring failure (including peeling, abnormal wear, and breakage) causes cylinder liner leakage to the crankcase, resulting in high oil mist. At this point, it is necessary to inspect the cylinder liner and piston ring, and replace any damaged ones. For example, when the main bearing or connecting rod bearing burns due to high temperature, causing local high temperature and increasing oil mist concentration, and stopping the machine, the explosion-proof manhole door should be opened to carefully inspect whether the connecting rod big end bearing and shaft are burned, and replace them if necessary.
5. There are many types of faults in the oil mist detector itself. Although these faults do not cause engine tripping, they can cause the diesel engine to lose important protection. Based on operational experience, as long as the following points are achieved, the failure rate can be minimized, the false tripping rate can be greatly reduced, and first-hand information can be provided for inspection after tripping.
⑴ Maintenance personnel should perform regular maintenance. Regularly replace the air filter and pressure reducing air filter, drain the moisture from the condenser tube, clean the oil stains in the valve box, clean the infrared probe with alcohol, blow the sampling tube, oil circuit, and air circuit with compressed air, and conduct necessary alarm tests and high oil mist protection action tests (the simplest method is to blow a puff of cigarette smoke into the sampling tube inlet).
When the generator set is running, the operator should carefully monitor the relevant parameters such as bearing temperature and lubricating oil temperature, and regularly observe the working condition of the oil mist detector, the indication of oil mist concentration, the difference between the U-shaped differential pressure gauge of the crankcase, whether the crankcase ventilation device is smoking, whether the crankcase explosion-proof door is hot to the touch, and whether there is an alarm for the high pressure difference of the crankcase. If a high oil mist trip occurs, the concentration value, valve box flipping situation, differential pressure gauge difference of the crankcase, abnormal bearing temperature, and the indication of each indicator light of the oil mist detector should be recorded as soon as possible.
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