Research on Common Faults Maintenance Technologies of Small Diesel Generating Set

- Dec 14, 2017 -

1. Perfectly complete inspections before maintenance

In order to ensure the maintenance work of small diesel generating set to be carried out smoothly, the inspections before maintenance of the generating set should be completed perfectly to prevent some external factors from influencing the normal operation of the small diesel generating set. Generally speaking, the main inspection contents should include the followings: ① Inspect whether the oil meets the relevant standards and codes to ensure that the oil can be used normally;  Inspect the pull rod of the electromagnetic fuel valve of the electric generator to ensure that the rod is in manual or electric starting location;  Pay attention to carrying out the strict inspection on the accumulator with the voltage more than 12V to determine whether there is electricity in the accumulator.

2. Analysis on common faults and their solutions

2.1 Analysis on the common faults of the starting part of the generating set

The fault of the starting part is one of the common faults of the small diesel generating set. The faults of the starting part are analyzed based on the two conditions, i.e. fault of the manual starting part and fault of the electric starting part. For the manual starting part, the more common fault is damage of manual digging rope, the specific expression forms of which are breakage of digging rope, immobility of digging rope and damage of digging rope coil etc. When carrying out the inspection on the starting digging rope, the repair should be carried out step by step according to the fault reasons having been found. For the electric starting part, more faults exist in the electric starting part compared with the manual starting part, the reason of which is that the electric starting part consists of more components generally including accumulator, starting switch, motor magnetic switch and electromagnetic fuel valve etc. Common faults of the electric starting part include:  Accumulator problem: the accumulator directly affects the starting status of the magnetic switch. Insufficient accumulator voltage will affect the starting of the generating set. In this case, the accumulator should be charged according to the fault reason having been found by inspection. In the wild, the standby accumulator can be prepared for replacement.  Magnetic switch problem: the more common phenomenon is that actuation of the magnetic switch fails but the magnetic switch is live and the accumulator voltage is sufficient, the reason of which may be that the magnetic switch has been damaged. In this case, replacement should be carried out by the maintenance personnel.  Starting module problem: if the voltage fails to provide the electricity to the electromagnetic fuel valve normally, the oil supply problem of the electromagnetic fuel valve will occur, but the motor of the generating set can still operate normally. In this case, the maintenance personnel should replace the starting module to ensure the normal operation of the generating set.  Electromagnetic fuel valve problem: the fault of the electromagnetic fuel valve of the small diesel generating set can result in the voltage problem and thereby cause the failure of the normal oil supply. Thus, in this case, the accurate inspection should be carried out on the electromagnetic fuel valve; in addition, repair should be mainly adopted and replacement should be the secondary selection.

2.2 Analysis on the common faults of the diesel engine part of the generating set

Diesel engine is an important part of the small diesel generating set. Once the diesel engine has a problem, it will have a great impact on the normal operation of the generating set. Thus, it is of the significant importance to research and analyze the common faults of the diesel engine. Under normal conditions, the faults of the diesel engine part include:  Blocking of air filter: as the important component for ensuring the smooth path of the intake and exhaust valves of the diesel engine, the air filter may be blocked after the diesel engine has been used for a period of time, after which the intake and exhaust valves will be obstructed and the diesel engine will release black smoke, thus the diesel engine cannot be started normally. In this case, it needs to clean or replace the air filter of the small diesel generating set that has been used for a long period of time.  Blocking of oil pipe of the diesel engine: Oil pipe is the equipment component, which is used for ensuring the smooth oil supply of the diesel engine. If the oil pipe or the diesel oil filter is blocked, the oil supply can be influenced and then the diesel engine will not be started normally. In this case, the oil pipe should be cleaned or replaced.  Relatively low pressure of the fuel spray nozzle: The main function of the fuel spray nozzle is to atomize the diesel oil. In case of insufficient pressure of the fuel spray nozzle, incomplete atomization will happen and the diesel engine will release black smoke. In severe case, the diesel engine cannot be started.  Fault of oil pump of the diesel engine: in this case, bush-burning of the diesel engine may occur. At this time, the maintenance personnel must determine the reasons why the fault of oil pump of the diesel engine occurs, such as damage of oil pump and too large clearance between bearing bushes etc., and then carry out the repair work.

2.3 Analysis on the common faults of the control cabinet of the electric generator

The common faults of the control cabinet of the electric generator specifically include:  Loss of excitation  of stator winding, affecting the power generation work: in this case, a certain measures need to be used for magnetizing. The magnetizing can be completed by dry battery.  Fault of rectifier bridge, damage of AVR voltage regulating module, damage of over-current and over-voltage protection modules, etc.: replacement is the best treatment method.  Bend or damage of the rotor spindle: in this case, the generator blade is difficult to start, thus, timely repair and replacement need to be carried out.  Voltage instability: the main expression form of the voltage instability is voltage drop. The main reasons are fault of excitation part and fault of single-phase grounding etc. Repair should be carried out only after the reasons have been determined.

3. Key points of maintenance of the small diesel generating set

In the maintenance process, following principles should be adopted: First of all, attention should be paid to inspections before maintenance to eliminate the inability to start arising from improper use; Secondly, during the use of diesel generating set, it is best to use electric starting; Finally, the periodical upkeep must be carried out on air filter, diesel oil filter, oil pipe and accumulator etc. of the diesel generating set to ensure the normal operation of the diesel generator.

4. Conclusion

According to the common faults analyzed in this paper and their corresponding treatment methods, the emergency maintenance can be made on some common faults of the small diesel generating set and the service performance of the diesel generating set can be guaranteed basically. However, types of faults of the small diesel generating set are relatively complex and substantial, thus, the maintenance personnel should carry out the in-depth research and analysis based on the actual fault conditions, to guarantee the complete maintenance and prevent worsening of faults of the generating set arising from maintenance error.

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