Generator set is mainly composed of engine, AC synchronous generator and control box (screen). The engine is part of the genset that generates power and is the most prone to failure. There are internal and external causes for diesel generator failure.
1. Properties of material and oil
In the process of design and manufacture, the materials should be correctly selected according to the working properties and characteristics of generator parts. The main reasons for the wear, corrosion, deformation, rupture and aging of the parts are the improper selection of materials, material disconformity and improper substitute. The properties of various materials and oils used in the unit can be summed up in three aspects, including physical, chemical and mechanical properties. Many faults of the generator set are the result of the influence of external factors through these properties. If the metal material is deformed, it will be oxidized under the action of high temperature; the nonmetallic material will be aged, and the acid substance in the oil Corrosion of metals can also cause oil to deteriorate.
2. Structural characteristics of Machine parts
Each machine part of the generator set has its own characteristics in the form of structure. In the work, external factors often play a role through these characteristics, making the relevant parts failure. For example, because of the structural characteristics of the engine water jacket, under the action of high temperature, the cooling water forms scale on the outer wall of the cylinder sleeve, which affects the cooling effect of the cylinder sleeve.
3. Working characteristics of Machine parts
Wear is caused by friction between parts that are in direct contact with each other and are in relative motion. For example, the piston ring of a diesel engine is in direct contact with the cylinder. During the working process, the piston ring moves in the cylinder at a high speed and reciprocates in a straight line, resulting in wear and tear of the cylinder. A component whose temperature varies sharply during work, resulting in deformation and cracks due to thermal stress. For example, in the working process of diesel engine, the internal stress of cylinder block and cylinder head is redistributed to a new balance due to the effect of high tide, resulting in warping deformation of cylinder head plane.
The operator did not use the unit in accordance with the operating rules. If running at low speed often, the load will increase quickly without heating machine, the oil pressure will be too low and so on will accelerate the wear and tear of the parts, the working time is too long, the load change is too big, the long-term overload operation and so on will also cause the premature damage of the parts.
2. Poor maintenance
In the maintenance of the unit, not strictly in accordance with the prescribed technical requirements to complete the work, or to take the wrong operation method, resulting in human failure and so on. In peacetime maintenance, to timely change oil, regular cleaning of air filters and water tanks, and so on. Carry out daily maintenance and one, two and three level maintenance as required.
3. Repair quality is not high
In the repair process, if the processing is not proper, the repair technical requirements are not reached, such as the improper matching clearance of the parts, the lack of smooth and clean surface, and the unclean cleaning during the assembly will make the unit malfunction in the process of use. The accuracy of each part's position is also very important in the process of assembly. If it fails to meet the requirements, it will lead to additional stress, produce side wear and other adverse consequences, and accelerate the failure of the parts.
The establishment of reasonable maintenance system and strict implementation of technical maintenance and operation rules for diesel generating units are important conditions for ensuring reliable work and prolonging their service life. In addition, regular use of maintenance staff training, improve their business level.
The disassembly of diesel generator set should be reduced as much as possible. To disassemble the generator set blindly or easily because of confusion and fluke will not only prolong the time of troubleshooting and delay the use of the genset, but also may cause undue damage or cause new faults. Starlight recommends that users disassemble units only as a last resort after careful analysis.
In general, through comprehensive inspection and careful analysis of diesel generating set, the possible causes of the failures of diesel generating set are preliminarily determined, and the main causes of the failures are first set out. Gradually narrow down the fault area (or area) so that the fault can be eliminated quickly and accurately. Therefore, this step is the key to the whole process of troubleshooting. In the long-term practice, the extensive use and maintenance personnel have accumulated and created a lot of effective, simple and practical judgment and troubleshooting methods. The main methods of troubleshooting the generator set are as follows.
1. Spacing method
In the process of fault analysis of diesel generator sets, it is often necessary to stop or partition the work of some part or system intermittently, so as to observe the change of fault phenomenon, or to make the fault phenomenon more obvious, so as to judge the fault location or machine parts. In the analysis of engine failure, the commonly used cylinder stopping method is one of the partition methods, that is, to make one cylinder of the multi-cylinder machine stop the oil supply in turn, in order to check the cylinder, or according to the change of the fault phenomenon, To distinguish whether the fault is local or universal. For example, if a black smoke is found to be emitted intermittently, and after a cylinder is stopped, the malfunction will disappear, which indicates that the location of the fault is in the cylinder, and further analysis should be made to find out. If there is no obvious change in the failure phenomenon of each cylinder, it is not a fault of individual cylinder, and the reason that has influence on the work of each cylinder should be found. In order to narrow the fault range of electrical equipment, it is sometimes possible to use the partition method to temporarily separate a part from the circuit when analyzing the fault of electrical equipment.
When analyzing the fault of generating set, if there is doubt about one part, the spare parts can be replaced by spare parts or replaced with the same parts. According to the change of fault phenomenon, to determine whether or not the fault occurred, or to identify the fault location.
3. test and verify
In order to verify whether the conclusion of fault analysis is in accordance with the reality or as a remedy for the lack of experience, the method of verification is used to observe the change of fault phenomenon by means of exploratory disassembly and adjustment for some parts or parts of the engine. A method that is often used without certainty as to where the fault is. It is difficult to distinguish the cause of fault when several kinds of abnormal phenomena of different reasons appear simultaneously, or when the cause of fault is related to improper adjustment. In this case, the verification method can also get better results. For example, it is suspected that serious wear of cylinder sleeve is caused by bad compression of a certain cylinder. A little oil can be poured into the cylinder (about 4%) If the g), compression force increases, then the doubt is true. For example, diesel engine smoke, suspected that the fuel supply is too large, but also the amount of fuel supply can be tentatively adjusted to verify that the doubt is true. When adopting tentative measures, we should abide by the principle of "less disassembly" and avoid disassembling the assembly casually. Either exploratory disassembly or adjustment should be carried out with confidence that it will return to its normal working condition and that it will not have adverse consequences as a result. In addition, some tentative disassembly and adjustment should be avoided at the same time in order to avoid mutual influence and misjudgment.
4. Variable speed
If the internal combustion engine has a fault, the fault phenomenon may change in the instant of increasing or decreasing the internal combustion engine speed. When observing the fault phenomenon, we should choose the appropriate speed to make the fault phenomenon more prominent. Generally speaking, low-speed operation is used, because internal combustion engine speed is low, the fault phenomenon lasts for a long time, easy to observe. For example, the valve gap of internal combustion engine valve mechanism is too large to cause "da" knock sound, this method can be quickly eliminated.