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Analysis of Circuit Protection Principle of Diesel Generator Sets

Sep. 28, 2022

Diesel generator sets often have circuit protection during use, so what exactly is the circuit protection? As a leading domestic brand of diesel generator sets, Starlight Power believes that the circuit protection of diesel generator sets is mainly caused by the following three reasons of:


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1. Reverse power: The phenomenon of reverse power is caused by the different speed (frequency) and voltage of the diesel generator set, that is, one diesel generator set has positive power, while the other one has negative power. That is to say, the unit with negative power becomes a load at this time (the frequency of this unit is low and the rotational speed is inconsistent). When the voltages are not the same, the unit with high voltage will provide a reactive current and reactive voltage to the unit with low voltage (the ammeter of this unit indicates the positive direction), which is equivalent to adding a phase control unit in the power supply system. The unit with low voltage becomes a large load at this time, receiving a large reactive current of a generator unit to maintain the voltage balance of the two units (the ammeter of this unit indicates the reverse direction). When monitoring, adjust the voltage of a certain unit higher or lower the voltage of another unit, causing a unit to have a reverse power current, and its operating current is about 20% of the rated current. The reverse relay acts, trips, and alarms, but does not stop.


2. Overcurrent: the rated power of the current diesel generator set is certain, its overload capacity is very low, basically about 5% of the rated power, the allowable load time is 15~30 minutes, and the maximum is not more than 60 minutes. , the diesel generator set will heat up, the wire insulation will be reduced, and the service life will be reduced. Therefore, if there is no special requirement when setting the overcurrent protection, the overcurrent protection can be set at 110% of the rated current. During the on-load test, bring the current to 110% of the rated current, and the overcurrent relay will act. Trip, alarm, no shutdown.


3. Overvoltage: when using diesel generator sets in parallel, the most fear is that the power supply system will oscillate. Once the voltage of the oscillating system rises, it is easy to cause the insulation breakdown of the electrical equipment and the power supply equipment, and the power supply equipment and the electrical equipment will be paralyzed together. . For this purpose, the diesel generator sets used in parallel are equipped with overvoltage protection, and the setting value is 105% of the rated voltage is the best. Short-circuit over-voltage relay, trip and stop, alarm action.


Starlight Power has advanced testing equipment, modern production technology, professional manufacturing technology, perfect quality management system, and strong technical research and development capabilities. It can provide 3KW~2500KW various specifications of ordinary, automatic, four protection, automatic switching, low noise and mobile generator sets, high quality and low energy consumption to meet the diverse power needs of customers, and can also meet users with different voltages and different frequencies. It is required to create a parallel power supply system for multiple units. If you are interested in our product or any question on generator, welcome to send email to sales@dieselgeneratortech.com.

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