柴油發(fā)電機組油霧保護系統(tǒng)常見故障及對策：

1、元件老化，溫度漂移等引起靈敏度改變

　　結合電廠的實際并經有關專家同意，將報警閥值S開關調至第4級（原4臺機組均在第3級），運行至今未發(fā)生跳機現(xiàn)象。

2、電子板故障

　　當油霧探測器出現(xiàn)紅、綠指示燈全部熄滅的現(xiàn)象，且檢查24VDC電源正常、插頭無松動時，基本上就可判斷為電子板故障，也可以采用對換其它柴油發(fā)電機組的電子板來進行判斷。如確屬電子板故障，就應該及時檢修或更換。

3、曲軸箱油氣中含有大量的水分

　　由于水分的存在，使得測量通道內的不透明度大大增加，致使電子裝置發(fā)生誤報。這就需要檢查潤滑油中是否含有水分、潤滑油冷卻器是否泄漏、空氣系統(tǒng)是否過度潮濕及油霧探測器底板內的加熱器是否工作正常等。近幾年來，通過對高油霧跳機事件的分析發(fā)現(xiàn)，真正高油霧跳機為0%，高水份跳機為98%（而且最后檢查，95%都是因潤滑油冷卻器的泄漏引起的），其余故障為2%（如電子板故障、繼電器誤動等）。所以如果在潤滑油進機管道上加裝一套高靈敏度的水份檢測裝置用于報警，就可以在水份過高時及時提醒運行人員，降低具有破壞性的跳機次數(shù)，增加電網的穩(wěn)定性。

4、裝設油霧探測器裝置的根本目的是監(jiān)測柴油機本身曲軸箱內部的工作狀況是否發(fā)生變化。比如活塞環(huán)失效（包括剝落、異常磨耗、折斷）造成缸套漏氣到曲軸箱，形成高油霧。這時要檢查缸套及活塞環(huán)，損壞的要更換。又如主軸瓦或連桿軸瓦高溫燒瓦造成局部高溫，造成油霧濃度增大而停機時，要打開防爆人孔門，仔細檢查連桿大端軸承及軸是否有燒傷，必要時更換。

5、油霧探測器本身的故障類型比較多，這些故障雖不會引起跳機，卻會使柴油機失去重要的保護。根據(jù)運行經驗總結，只要做到以下幾點，就可將故障率降低到最低，也可使誤跳率大大降低，并為跳機后的檢查提供第一手資料。

　⑴維護人員應做好定期維護。定期更換空氣濾片、減壓空氣濾片，排出冷凝管的水分，清洗閥箱的油污，用酒精清洗紅外探頭，用壓縮空氣吹掃采樣管、油路、氣路，并做必要的報警試驗及高油霧保護動作（最簡單的方法是從采樣管入口處吹一口香煙的煙霧進去）試驗。

　⑵發(fā)電機組運行時，運行人員應認真監(jiān)測軸承溫度、潤滑油溫度等有關參數(shù)，并定時觀察油霧探測器工作狀況、油霧濃度的指示情況、曲軸箱U形差壓計的差值、曲軸箱透氣裝置有無冒煙、曲軸箱防爆門是否燙手、曲軸箱高壓差有無報警等。如發(fā)生高油霧跳機應盡快記錄濃度值、閥箱翻牌情況、曲軸箱差壓計的差值、軸承溫度有無異常及油霧探測器各指示燈的指示情況等。

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.