Analysis of Automatic Shutdown of Diesel Generator Under Heavy Load

The total power generation time of a 200KVA diesel generator was less than 60 hours, and the external load current of 120A automatically stopped during an emergency power generation. After several hours of troubleshooting, it was finally recovered.

1. Fault phenomenon: the diesel generator engine starts normally and the idle speed is normal. When the peripheral load is switched on and off, the current is from 0 to 120A. About 1 minute, the diesel generator engine speed drops significantly and emits black smoke until it stops.

2. Fault analysis: The diesel generator is configured as 200KVA, and the load current can reach about 360A. The engine of the diesel generator will automatically stop when the current load is only 120A. It is obvious that the engine power is insufficient, and there may be problems in the oil supply circuit.

3. Troubleshooting process: (1) replace the filter element and sediment core of the diesel generator, restart the engine of the diesel generator and generate power after the correct assembly, and automatically stop after the load can reach 160A current; (2) After opening the fuel tank discharge valve to discharge pollutants, it was found that there is a high moisture content in the diesel fuel. After removing the moisture, install the discharge valve and restart the engine. When the negative energy reaches 200A, the engine will still be shut down; (3) Open the fuel tank drain valve to completely drain all diesel fuel in the tank, and it was found that there are many impurities and dirt in the diesel fuel.

Flush the fuel tank with high-pressure pump air, then refill (filter oil with sandcloth) and flush the tank back and forth, releasing oil containing dirt and impurities until the discharged oil is very clear and free of impurities. Then refill the diesel (filter the diesel with gauze), restart the engine of the diesel generator, switch on the load and switch on the current until 340A (all possible loads at that time) operates normally and the fault is completely eliminated.

4. Experience summary: The root cause of this failure is the failure of the oil circuit of the diesel generator engine caused by improper daily use and maintenance. It took nearly 3 hours to maintain the engine to normal during emergency power generation, which can be said to be a failure of power generation. Experience summary: always filter the diesel fuel when adding it. Before starting the diesel generator engine, open the drain valve to drain a small amount of oil (water in the fuel).

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