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Why Does Diesel Generator Set Give Alarms?

Apr. 17, 2020

Diesel generator set is a power generation equipment, it uses diesel oil, driven by a diesel engine to generate electricity. The whole set of diesel generator is generally composed of diesel engine, generator, control cabinet, fuel tank, storage battery for starting and control, protection device, emergency cabinet and other components.

The alarm function of the diesel generator set will automatically start and sound when the diesel generator has the following conditions:

1.Over speed.

2.High water temperature in water tank.

3.Low oil pressure.

4.Over current display on the control panel.

5.Over voltage.

6.When other abnormal phenomena occur, the alarm function of diesel generator set starts or the self-protection function of diesel generator plays a role.

 Diesel generator

What is the reason of faults for low voltage shutdown?

1.Mechanical speed regulation of diesel engine

Diesel engine speed regulation includes electronic speed regulation and mechanical speed regulation. If it is mechanical speed regulation, there is an oil pump mechanism on the diesel engine to control the oil volume and oil circuit, it seems called common rail oil pump. There is a pull rod on it to control the oil quantity. It is called speed regulating pull rod temporarily. A speed limiting (high-speed) top rod and speed regulating top rod are distributed on both sides of the speed regulating pull rod, and the low pressure will be reported after starting and running for 20s. If the voltage and frequency is still not in normal value, the reason may be speed. We can try to adjust regulation top rod. If diesel genset has faults, there must be a main fault. After resolving the main fault, all problems will be resolved.

2.Voltage sample line loose

If the line is loose, there will be no voltage.

3.Residual magnetism

If the generator has no residual magnetism, the voltage system of the generator cannot be built at the beginning. For this problem, we need to know how much voltage the excitation output of the AVR regulator plate of the generator is, and then connect the corresponding voltage source on the excitation output line for magnetization (the voltage type should be corresponding, and the polarity should not be reversed).

3.Grounding fault

If the outgoing line is three-phase grounded, the voltage and current are very low. At this time, it is mainly to check whether the grounding discharge device (such as the grounding knife) is closed or grounded.

4.Regulating plate fault

Due to the change of environmental factors, the parameters of AVR pressure regulating plate are no longer applicable and need to be readjusted. Generally speaking, this kind of problem will not appear in non parallel diesel gensets. Because the parameters of the pressure regulating plate are fixed value (400V), we can't adjust them generally. Only the unit used for parallel operation may have this problem. Because AVR voltage regulator is regulated according to the voltage of main bus during parallel operation, it is not unchangeable. At this time, there is a voltage regulating signal sent to AVR voltage regulator by parallel operation device. In this case, either check whether the voltage regulating signal is connected wrongly or try to use electronic control (parallel operation device, voltage regulator, etc.) to readjust the voltage quickly when starting up.


5.The varistor or rectifier bridge diode on the generator winding is damaged

The function of varistor is to turn on the varistor in case of over-voltage fault to reduce voltage. If the varistor is broken down or turned on for other reasons, it can be imagined that the voltage must be very low. The rectifier bridge has 6 diodes. The set DC power supply is used to supply the regulator and excitation devices. If the rectifier bridge diodes are damaged, the function of the regulator and excitation devices will be greatly weakened buckle.


Hope above information is helpful to you. We also supply whole set of diesel generators, we have our own factory in Jiangsu China since 1974. If you are looking for diesel generators, please contact us by email sales@dieselgeneratortech.com, we will work with you.

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