What are the causes of diesel generator set undervoltage fault alarm shutdown?

1, diesel engine speed control problems diesel engine speed electronic speed control and mechanical speed, if it is mechanical speed control, then in the diesel engine has a control oil and oil pump mechanism, it seems to be called a common rail pump, there are The tie rods are used to control the amount of fuel. For the time being, it is called the speed adjustment rod. A speed limit (high speed) jack and a speed control jack are arranged on both sides of the speed regulation rod. The 20S is used to report the low pressure when starting the speed control rod. The voltage and frequency are not known. If you can't go up, if you can't keep up, it may be caused by the speed not being able to adjust. You can adjust the speed control top rod to try it. However, if the diesel engine group fails, there is usually a major fault, and the main fault is solved. A series of minor faults are then resolved.
2, the voltage sampling line loose This is a good understanding, voltage sampling line loose, it is certainly not measured voltage.
3. Remanence If the generator has no remanence, then the voltage system of the generator cannot be built at the beginning. For this problem, we have to know how much the V output of the generator AVR Regulator plate excitation output is, and then The excitation output line is connected to the corresponding voltage source for magnetization (the voltage type must correspond and the polarity should not be reversed).
4. Ground fault If the three-phase grounding of the outgoing line, then the voltage and current is very low, this time mainly to check whether the grounding discharge device (such as ground knife) is closed or grounded.
5, regulator board failure may be due to changes in environmental factors, AVR regulator board parameters are no longer applicable, need to be re-adjusted, in general, non-parallel diesel engine group basically does not appear this problem, because the regulator board The parameter is fixed value (400V), in general we can not adjust, only the unit used for parallel machine may have this kind of problem, because the AVR Voltage Regulator is adjusted according to the main bus voltage in the parallel machine, it is not Invariable, this time, the parallel device usually has a pressure regulating signal sent to the AVR regulator board. In this case, it is necessary to check whether the regulator signal is connected to the wrong one, or try to use the electronic control (parallel device, Regulators, etc.) Reset the voltage.
6. The function of the varistor or rectifier bridge diode on the generator winding to damage the varistor is: when the overvoltage fault occurs, the varistor is turned on to depressurize. If the varistor is broken down or turned on for other reasons, then It is understood that the voltage must be very low, the rectifier bridge has 6 diodes, and the set DC power supply is used to supply the voltage regulator and excitation devices. If the rectifier diode is damaged, the functions of the regulator and excitation will be greatly reduced.