Diesel generator sets operate under a small load. With the continuation of the running time, the following five hazards will occur:
- Piston-cylinder liner seal is not good, the oil runs up, enters the combustion chamber and burns, and the exhaust emits blue smoke;
- For a supercharged diesel engine, the boost pressure is low due to low load and no-load. It is easy to cause the sealing effect of the supercharger oil seal (non-contact type) to decrease, and the oil escapes into the supercharger chamber and enters the cylinder with the intake air;
- Part of the oil that goes up to the cylinder participates in the combustion, and part of the oil cannot be completely burned, forming carbon deposits on the valve, intake port, piston top, piston ring, etc., and part of it is discharged with the exhaust. In this way, oil will gradually accumulate in the exhaust port of the cylinder liner, and carbon deposits will also be formed;
- When the oil in the booster chamber of the supercharger accumulates to a certain extent, it will leak out from the joint surface of the supercharger;
- Long-term low-load operation will lead to more serious wear and tear of moving parts, deterioration of engine combustion environment, etc., which will lead to the consequences of early overhaul period.
Therefore, foreign diesel engine manufacturers emphasize that the use of naturally aspirated or supercharged models should minimize the low-load/no-load running time, and stipulate that the minimum load cannot be lower than 25%-30% of the rated power of the unit.