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What Are the Common Problems of Diesel Generator

May. 17, 2019

Common problems of diesel generating sets are listed below:

18. ATS self-switching operation steps:

1. Module manual operation mode:

After turning on the power key, press the “Manual” button of the module to start directly. When the generating set starts successfully and runs normally, at the same time, the automation module also enters the self-test state, it will automatically enter the speed-up state. After the speed is raised successfully, the unit will automatically close and connect to the power grid according to the display of the module.

2. Fully automatic operation mode:

Set the module in the "automatic" position, the unit enters the quasi-start state, and in the automatic state, through the external switch signal, the mains state is automatically detected and judged for a long time. Once the mains fails or loses power, it will enter the auto start state immediately. When the mains comes, it will automatically switch to the off-speed and stop. When the mains returns to normal, the system will automatically trip to the network after 3S confirmation, delay 3 minutes, automatically stop, and automatically enter the next automatic start preparation state.

19. What should I do if the cylinder seal of the diesel generator set becomes low?

When the engine is cold-started, especially in winter, the oil on the piston ring and the cylinder wall is small, the sealing effect is not good, and there is a phenomenon that the engine is repeatedly started and cannot be ignited. Sometimes, diesel power generator sets have a serious impact on the sealing performance of the cylinder due to heavy cylinder wear, making starting more difficult. In this regard, the injector can be removed, and 30-40 ml of oil is added to each cylinder to enhance the sealing performance of the cylinder and increase the pressure during compression.

20. Self-protection function of diesel generator.

Diesel engines and alternators are equipped with various sensors, such as water temperature sensor, oil pressure sensor, etc. Through these sensors, the operating status of the diesel engine is intuitively displayed to the operator, and with these sensors, an upper limit can be set. When the limit value is reached or exceeded, the control system will pre-alarm. At this time, if the operator does not take measures, the control system will automatically stop the unit. It is in this way that diesel generating sets play a self-protective role.

The sensor plays a role of receiving and feedback various information. It is the control system of power generator that really shows these data and performs the protection function.

diesel generator set

21. What are the sources of noise from diesel generating sets?

Intake noise, exhaust noise, and cooling fan noise

Combustion noise in combustion chambers, mechanical noise in engine component friction

Noise generated by high-speed rotation of the rotor in an electromagnetic field

22. Start-up skills of diesel generator in winter.

Preheating: The cooling system can heat the water and heats the oil sump with a heat source.

Improve air tightness: The injector can be removed, and 30-40ml oil is added to each cylinder to enhance the sealing performance of the cylinder and improve the pressure during compression.

Turning: Shake the crankshaft before starting, so that it can run easily after starting.

23. What is the role of the piston ring of a diesel generator set?

Heat transfer

Control oil

Supporting effect

Keep airtight



24. How many ways and sequences can the new machine run in?

Cold running-in, manual rotation, or external force to drive the crankshaft to rotate.

After hot running-in, no load running in.

25. What is the cause of engine oil deterioration?

Use oil with the wrong oil grade and the quality is not up to standard.

The unit is in bad operating condition, such as gas channeling, oil channeling, excessive clearance, and high oil temperature.

The unit is often operated at low temperature.

The exhaust gas enters the oil sump and condenses into moisture and acid.

The oil filter is too dirty, the filter leaks inside, and the oil is not filtered through the filter.

26. What is the role of oil pump?

The function of the oil pump is to give the lubricating system a sufficient pressure of the oil to effectively lubricate each moving part. At present, the gear type and rotor type oil pump are widely used on the diesel engine.

injection pump

27. What is the function of governor?

The governor should be able to adjust the oil supply amount sensitively according to the change in external load to keep the speed stable. It must have two basic parts: the sensing element and the actuator.


28. What is the function of automatic regulator?

Automatic Voltage Regulator (AVR) keeps the generator tightly regulated from no load to full load. AVR has a proportionality of the voltage frequency (Hz), which is properly adjusted to reduce the output voltage when the rated speed is reduced. This feature helps protect the engine when a large load is suddenly added.

29. How to maintain battery?

For the machine that is often used, battery is generally free of problems. If it is not used for a long time, the battery should be checked regularly and charged, and charged every 12 weeks ( 8 weeks in the tropics).

30. Under what circumstances will the unit automatically delay the shutdown?

The fuel level is too low, the water temperature is too high, the water level is too low, the load is overloaded, the start fails, and a corresponding signal is sent.

31. Under what circumstances will the unit have an emergency shutdown?

Overspeed, short circuit, phase loss, high voltage, voltage loss, low frequency

32. Under what circumstances will the unit automatically emit an audible and visual alarm signal?

Low oil pressure, high water temperature, low water level, overload, start failure, overspeed, short circuit, phase loss, high voltage, voltage loss, low frequency, low battery voltage, high battery voltage, low oil level and the alarm system of unit has relay contacts.

33. What is the type of oil filter for diesel generator sets?

Mechanical separation

Centrifugal separation

Magnetic adsorption

generator filters

34. What is the reason why the compression ratio becomes smaller?

The position of the piston at the end of compression is low: wear and deformation of the relevant parts.

The volume of the combustion chamber becomes large: valve seat ring wear, piston top depression, cylinder pad is too thick.

35. What are the automatic control functions of the diesel genset?

Automatic heating device

Automatic adjustment of diesel engine speed

Charging system

Instrument system

protective device

Starting system


36. How does automatic heating device work?

In diesel engine, a cooling water automatic heating device is generally installed, so that when the generator set is in the standby state, the diesel engine should be in a heat engine state, so that the generator set can start up and work with load within 15s when the mains loses power.

The automatic heating device of the diesel engine, when the water temperature is lower than 30°C, the thermostat contact is connected, the KM is sucked, and the heater EH is operated. When the water temperature rises to 50 degrees Celsius, the thermostat contact is disconnected, KM is released, and the heater EH is de-energized.

In addition to the cooling water heating device, there is also oil heating device and battery heater.

37. How to observe the power of the maintenance-free battery with eye?

There is usually a transparent observation port above the battery. When we look down from the top, we can see the color inside. If it is green, it indicates that the battery is fully charged. If it is white, it indicates that it needs to be charged. If it is black, it means it needs to be replaced.

38. What is the white solid on the battery terminal?

This is a normal phenomenon. The white solid is the product of the battery post and the oxidation of the air. When it is cleaned, it will disappear when washed with boiling water.

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