How to Start A Diesel Generator Step by Step?

Diesel generator sets provide stable and reliable power and are primarily used in scenarios where grid power is unavailable or as emergency backup power sources. As core equipment for emergency power supply, the standardization of their startup procedures directly impacts equipment lifespan and electrical safety. Let's explore the startup steps for diesel generators and the precautions to be taken during the startup process.

1. Pre-startup Inspection

Before a normal startup, confirm that the diesel generator set's engine oil, diesel fuel, coolant, and battery electrolyte are all within the specified ranges.

Check the engine oil level and quality. Check the oil level in the oil pan. Pull out the dipstick beside the crankcase and observe whether the oil level meets the required height. Take a small amount of oil on the dipstick and rub it between your fingers. If the oil viscosity feels normal, it indicates the oil is still usable. Otherwise, it should be replaced promptly. Observe the oil color. If it turns milky white, it indicates a significant amount of water in the oil, and the cause should be quickly identified and the issue resolved.

Ensure an adequate diesel fuel supply. Otherwise, running out of fuel mid-operation or an unexpected shutdown during diesel generator operation could cause damage such as faults in the generator's exciter, leading to unnecessary economic losses. Open the vent screw on the high-pressure fuel pump to remove air from the low-pressure fuel line.

Check if the coolant level in the radiator is sufficient. If not, top it up with clean, soft water. Insufficient coolant below the specified standard can cause the diesel engine body temperature to become excessively high, potentially leading to serious issues like cylinder gasket failure.

Inspect the electric starting system. First, check if the electrolyte density of the starting battery is within the range of 1.240–1.280 kg/L. A density below 1.180 kg/L indicates insufficient battery charge. Check if the electrical wiring connections are correct. Inspect the battery terminals for dirt or oxidation, and clean them thoroughly. Check the electrical contacts of the starter motor and electromagnetic control mechanism to ensure they are in good condition.

2. Starting the diesel generator set

Diesel generating sets are generally started either conventionally (without auxiliary measures) or with auxiliary measures for low-temperature starts. In winter or cold conditions, ensure good fuel supply and sufficient battery capacity and voltage.

Pre-start warm-up (applicable in winter or low-temperature environments): First, open the fuel valve. Then, press and hold the preheat button (if the genset is equipped with a preheating device) for 30 seconds to 1 minute to raise the engine block temperature. During this time, closely observe whether the preheat indicator light illuminates to confirm the preheating system is functioning properly.

Starting procedure: Insert the start key into the ignition switch on the control panel and turn it clockwise to the START position. Maintain this position for 3-5 seconds while carefully listening for exhaust sounds or observing the tachometer to determine if the engine has successfully ignited. If the startup attempt is unsuccessful, wait 10 seconds before repeating the operation to avoid excessive battery discharge.

Post-startup warm-up: After starting, let the engine run stably at a low speed for 3-5 minutes to allow full lubrication and warming of all engine components. Check if all parts of the diesel engine are operating normally. Then gradually increase the speed to the rated value and enter partial-load operation. Only allow full-load operation after the diesel engine's outlet water temperature exceeds 70°C, the oil temperature exceeds 50°C, and the oil pressure exceeds 0.25 MPa.

3. Monitoring during generator set operation

During diesel generator set operation, closely monitor the fault indicator lights on the generator control panel, and observe whether the water temperature and oil pressure readings are normal. Additionally, check the generator set for any abnormal noises, vibrations, or leaks (water, oil, or air). If any abnormalities are detected, take immediate action to address them. After confirming that all data, including oil pressure, speed, voltage, and frequency, are normal, ensure it is safe to close the generator's output circuit breaker to begin supplying power. Check if the indicators on the generator's distribution panel are in a normal state.

4. Shutting down the diesel generator set

Before shutdown, first disconnect all non-critical loads to gradually reduce the diesel generator set's load. Then, open the output circuit breaker to completely disconnect the generator from the load.

Turn the control switch to the STOP position. The engine will begin idling, typically for 3-5 minutes. During this time, closely monitor the water temperature to ensure it drops below 70°C, and note when the oil pressure returns to zero. Once these conditions are met, the engine will shut down automatically.

In case of an emergency, immediately press the red emergency stop button to halt the engine rapidly. After an emergency shutdown, be sure to check the cause of the fault (e.g., high water temperature, low oil pressure), resolve any safety hazards, and then reset the relevant buttons.

After shutdown, close the fuel valve to prevent fuel leaks. Then, carefully inspect all components of the generator set for any oil or water leaks, and record the operational parameters in detail. If the generator set will be out of service for an extended period, it is recommended to start and run it once every two weeks to prevent component corrosion.

Mastering the correct startup steps for a diesel generator not only extends the equipment's service life but also ensures power supply safety during critical moments. If you would like to learn more about diesel generator sets or are interested in purchasing one, please feel free to contact Dingbo Power today.