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What is the reason for the alarm shutdown of a diesel generator set due to an undervoltage fault?

What is the reason for the alarm shutdown of a diesel generator set due to an undervoltage fault?

In fact, there are many main reasons why diesel generators can not reach the rated speed. The following are the main reasons cited by ITCPower:

  1. The mechanical speed regulation of diesel engine.
    Diesel engine speed regulation is divided into electronic speed regulation and mechanical speed regulation. If it is mechanical speed regulation, then there is an oil pump mechanism (that is, common rail oil pump) on the diesel engine that controls the amount of oil and the oil path. There is a tie rod on it to specifically control the amount of oil (that is, the speed control lever). A speed-limiting (high-speed) jack and a speed-adjusting jack are distributed on both sides of the speed control lever, and the low pressure will be reported after starting for 20S. If the voltage cannot rise all the time, it may be caused by the rotation speed not being able to rise, then you can try to adjust the speed adjustment jack. General diesel engine failures have a major failure. As long as the major fault can be resolved, a series of minor faults caused by it will be resolved accordingly.
  2. The voltage sampling line is loose.
    When the voltage sampling line is loose, it must be impossible to measure the voltage.
  3. Remanence.
    If the generator has no residual magnetism, the voltage system of the generator cannot be established at the beginning. When such a problem occurs, we need to know what the excitation output voltage of the AVR voltage regulator of the generator is, and then the excitation output line Connect the corresponding voltage source for magnetization (the voltage type should correspond, the polarity should not be reversed).
  4. Ground fault.
    If the three-phase grounding is out, the voltage and current are very low. At this time, it is mainly necessary to check whether the grounding discharge device is closed or grounded.
  5. The voltage regulator board is faulty.
    Due to changes in environmental factors, the parameters of the AVR pressure regulator are no longer applicable and need to be readjusted. Generally speaking, non-parallel diesel engines basically do not have this problem, because the parameter of the pressure regulator is a fixed value of 400V. In general, we can’t adjust it. Only the units used for paralleling may have this problem. Because the AVR voltage regulator board is adjusted according to the main bus voltage during parallel operation, it is not static. At this time, the parallel device generally has a voltage regulation signal sent to the AVR voltage regulator board. In this case, you can check the voltage regulator If the signal is connected incorrectly, you can also try to use the electronic controls (parallel device, voltage regulator, etc.) to readjust the voltage when starting up.
  6. The varistor or rectifier bridge diode on the generator winding is damaged.
    The function of the varistor is: when the overvoltage fault occurs, the varistor is turned on to reduce the voltage. If the varistor is broken down or turned on for other reasons, then it is conceivable that the voltage must be very low. The rectifier bridge has 6 diodes, and the set DC power is used to supply voltage regulator and excitation devices. If the rectifier bridge diode is damaged, the role of the voltage regulator and excitation devices will be greatly reduced.