Many users believe that the smaller the load of a diesel generator set, the more beneficial it is. In fact, this is a serious misunderstanding, because long-term low idle or no-load for more than 10 minutes will damage the engine. This is because the room temperature is too low to completely burn the fuel, causing carbon deposits to form around the injector nozzle and ring and causing valve adhesion.
If the engine coolant temperature is lower than 60°C, the unburned fuel will wash away the oil on the cylinder wall and dilute the oil in the crankcase, thereby affecting the quality of the lubricating oil and shortening the engine life. Therefore, the idling time should be shortened as much as possible to prevent this from happening.
The following are the five major hazards of low-load operation of diesel generator sets:
1. Part of the oil that rises to the cylinder participates in combustion, part of the oil cannot be completely burned, and carbon deposits are formed on the valve, intake duct, top, ring, etc., and part of it is exhausted. In this way, oil will gradually accumulate in the cylinder liner exhaust passage, and carbon deposits will also form;
2. When the lubricating oil in the supercharger chamber accumulates to a certain extent, it will leak out from the joint surface of the supercharger;
3. The cylinder liner is not well sealed, the engine oil rushes up and enters the chamber, and the exhaust emits blue smoke;
4. For supercharged diesel engines, due to low load and no load, the boost pressure is low, which easily leads to the sealing effect of the supercharger oil seal (non-type) to decrease, and the oil rushes into the supercharger chamber and enters the cylinder along with the intake air;
5. Long-term low-load operation will lead to increased wear of moving parts, engine deterioration and other consequences of early overhaul period. Generator manufacturers convert other forms of energy into electrical energy. Foreign diesel engine manufacturers emphasize that the low-load/no-load operation time should be minimized for both naturally aspirated and supercharged models, and the minimum load should not be less than 25%-30% of the rated power of the unit.
The long full-load operation time of the diesel generator set can not only improve its own performance, discover safety hazards, but also avoid accidents. The following are some specific precautions when the unit is running:
1. Before starting: Before starting each time, you must check whether the cooling water or antifreeze in the diesel engine water tank is lacking. If it is lacking, fill it up. Check the lubricating oil dipstick to see if the oil is lacking. If it is lacking, add it to the static full scale line, and then carefully check whether there are any hidden faults in the relevant components. If a fault is found, it must be eliminated in time before starting.
2. Pay attention to the operating status during operation: Cummins diesel generator, single bearing, 4 poles, brushless, anti-drip structure, insulation grade H, suitable for GB766, BS5000, IEC34-1 grade requirements. The generator can be used in sand, salt, seawater and chemical corrosion. During the operation of the generator set, there must be a dedicated person on duty, and always pay attention to a series of possible faults, especially the changes in lubricating oil pressure, water temperature, oil temperature, voltage, and other important factors. In addition, it is necessary to pay attention to the availability of sufficient diesel. If the fuel is interrupted during operation, it will objectively cause load parking, which may damage the generator excitation control and related components.
3. It is strictly forbidden to start the diesel engine with load: the diesel generator set uses the diesel engine as the prime mover and drives the synchronous generator to generate electricity. It is a power generation device with quick start, easy use, low investment and strong adaptability. Before starting the diesel engine, pay attention to the output air switch of the generator must be in the closed state. After the ordinary generator set diesel engine is started, it must go through 3-5 minutes of idling (about 700 rpm). The temperature is low in winter, and the idling time should be appropriate for a few minutes. After the diesel engine is started, first observe whether the lubricating oil pressure is normal and whether there are abnormal phenomena such as oil leakage and water leakage (under normal circumstances, the lubricating oil pressure must be above 0.2MPa). If any abnormality is found, stop the machine immediately for inspection.
If there is no abnormality, the diesel engine r/min is increased to the rated r/min 1500 rpm. At this time, the generator displays 50 Hz and the voltage is 400V, then the output air switch can be closed and put into use. The generator set is not allowed to run at no load for a long time. (Because long-term no-load operation will cause the diesel in the diesel engine injector to not be completely carbonized, causing valve and ring leakage.) If it is an automated generator set, there is no need to run at idle speed, because the automated unit is generally equipped with a water heater to keep the diesel engine cylinder at around 45°C. After the diesel engine is started, it can deliver power normally within 8-15 seconds.
4. It is strictly forbidden to shut down with load: before each shutdown, the generator manufacturer must gradually cut off the load and then shut down the diesel generator set.
In order to extend the service life of the diesel generator set and better play its role, we should pay attention to correct operation and maintenance, reduce the low load/no-load operation time and the minimum load unit cannot be less than 25%-30% of the rated power.
