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Reasons for Low Voltage of Backup Diesel Generating Set

Dec. 17, 2021

In the actual operation of diesel generator sets, due to some reasons, the output voltage will occasionally be unstable, which will inevitably affect the normal operation of the generator sets. In this article, Starlight Power Generation Equipment will analyze in detail several main reasons for this phenomenon:


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1. The prime mover's speed is too low. Treatment: Adjust the prime mover's speed to the rated value.


2. Excitation loop resistance is too large. Treatment: Reduce the resistance of the magnetic field rheostat to increase the excitation current. For semiconductor-excited diesel generator sets, check whether the additional winding joints are disconnected or connected incorrectly.


3. The motor brush of the exciter is not at the neutral position, and the treatment: or the spring pressure is too small. Adjust the brush to the correct position, replace the brush, and adjust the spring pressure.


4. Some rectifier diodes are broken down. Treatment: Check and replace the breakdown diode.


5. There is a short circuit or ground fault in the stator winding or the excitation winding. Treatment: Check the fault and clear it.


6. The contact surface of the brush is too small, the pressure is insufficient, and the contact is poor. Treatment: If the surface of the commutator is not polished, use emery cloth to polish the surface of the commutator at low speed, or adjust the spring pressure.


Treatment method for abnormal voltage of diesel generator set:


1. When the 220kV bus voltage is higher than the voltage curve scale of the long value rule, the excitation current of the diesel generator set should be adjusted in time to make the bus voltage normal without waiting for the long value command.


2. When adjusting the excitation current of the diesel generator set to make the reactive power of the generator set to the lowest allowed limit, the bus voltage is still higher than the voltage curve of the long value rule, the duty officer should immediately report to the duty leader for handling.


3. When the 220kV bus voltage is lower than the voltage curve scale of the long value rule, adjust the reactive power of the unit without waiting for the value long command. If the bus voltage is still unable to recover to normal after additional output, the system should be reported immediately to request the system to adjust the voltage.


4. Assuming that the system voltage drop and frequency drop occur at the same time, it should be dealt with according to the handling method of the frequency drop incident.


5. When the factory bus voltage drops to a low working voltage, in order to prevent the voltage from collapsing, the unnecessary factory power load should be reduced immediately to restore the factory bus voltage to above the low working voltage. And report to the head of duty.


Therefore, in order to ensure stable power transmission and the smooth development of work projects, users must regularly inspect and maintain diesel generator sets. When an abnormal situation occurs, do not force it to start. Professional staff should conduct an operation check and troubleshoot in time.


Starlight Power was founded in 1974 and is one of the earliest manufacturers of generators and diesel generator sets in China. If you want get more information, please feel free to send email to sales@dieselgeneratortech.com we will pay highly attention on your question.

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