Diesel Generator Set Running at Low Load will Signal Danger

Many users often have a serious misunderstanding, believing that the smaller the load of diesel generator sets, the better. In fact, this is very wrong. The reasonable range of running diesel generators is about 60-75% of the maximum rated load. When the diesel generator set reaches or approaches full load regularly, it is allowed to run at low load for a short time.Running a diesel generator set at low load will produce 3 hazard signals. Let's take a look.

1. Poor burning.

Poor combustion can cause soot formation and unburned fuel residue to block and clog the piston ring (in a reciprocating engine, in this case a generator, the piston ring is a split ring embedded in a groove on the outer diameter of the piston).This will form hard carbon, causing the injector to be blocked by soot, resulting in worse combustion and black smoke. Condensed water and combustion by-products usually evaporate at higher temperatures, forming acids in the engine oil, which only further complicates the problem. Unsurprisingly, this causes slow but extremely harmful wear of the bearing surface.

The normal maximum fuel consumption of the engine is about half of the fuel consumption at full load. All diesel engines must be operated above 40% load to allow complete combustion of the fuel and run the engine at the correct cylinder temperature. This sounds correct, especially in the first 50 hours of engine operation.

2. Carbon deposition.

The engine of the generator relies on sufficient cylinder pressure to force the piston ring to be tightly sealed in the hole (the diameter of each cylinder) to resist the oil film on the surface of the hole. When the hot combustion gas blows through the poorly sealed piston ring, causing the so-called flash burn of the lubricating oil on the cylinder wall, the so-called internal glass will be produced.This creates an enamel-like glaze that removes complex patterns that are designed to preserve engine oil and return it to the crankcase through an oil scraper ring.This harmful cycle can cause irreversible damage to the engine, and may cause the engine to fail to start and/or fail to reach maximum power when needed. After oil or carbon deposits occur, the damage can only be repaired by the following methods: dismantle the engine and re-boring the cylinder bores, process new honing marks and remove, clean and eliminate the combustion chamber, injector nozzles and the value of carbon deposits .

As a result, this usually results in higher fuel consumption, which in turn produces more carbonized oil or sludge. Carbonized engine oil is engine lubricating oil contaminated by carbon deposits. This happens naturally when the engine burns fuel, but when the piston rings are stuck and the cylinder bore becomes smooth, too much carbonized engine oil will be produced.

3. produce white smoke.

Operating the generator under low load may cause white smoke, which is generated from the exhaust gas with higher hydrocarbon emissions due to the lower temperature (because the fuel can only be partially burned at this temperature). When diesel cannot burn normally due to lack of heat in the combustion chamber, white smoke will be produced, which also contains a small amount of harmful toxins, or white smoke will also be produced when water leaks into the air intercooler. The latter is usually caused by a blown cylinder head gasket and/or a cracked cylinder head.As a result, the percentage of unburned fuel in the oil increases because the piston rings, pistons and cylinders cannot fully expand to ensure a good seal, which in turn causes the oil to rise and then be discharged through the exhaust valve.

When the generator set is used under a load that is less than 30% of the maximum power value, other problems that may occur are:

　　Turbocharger excessive wear

　　 Turbocharger housing leaks

　　 Increased pressure in the gearbox and crankcase

　　Cylinder liner surface hardening

　　The exhaust gas treatment system (ATS) is inefficient and may start the forced regeneration cycle of the DPF.

Long-term low-load operation of diesel generator sets will also lead to increased wear and tear of the operating components of the set and other consequences that deteriorate the engine, which will advance the overhaul period of the generating set. Therefore, in order to extend the service life of the diesel generator set and better perform its functions, Users should pay attention to correct operation and maintenance to reduce low-load running time.

The above are the dangerous signals that will be generated when running diesel generator sets at low load. If you are interested in diesel generators, please contact Dingbo Power by email dingbo@dieselgeneratortech.com.