General inspection
Lubrication system service
Cooling system service
Fuel system service
Service and testing of starter batteries
Regular tests of the generator engine
Use of diesel generator under Prime user
General inspection
When the diesel generator is working, the operator must be aware of the mechanical problems that are dangerous or may create unsafe conditions. In the following, we will introduce the parts of the diesel generator that need to be reviewed and checked regularly for its safe and reliable operation:
Exhaust system
While the diesel generator is working, inspect the entire exhaust system, including the exhaust manifold, storage tank, and exhaust pipe. All fittings, welds, gaskets and joints used throughout the exhaust system route must be free of any leaks and ensure that the area around the exhaust pipe route does not overheat. Any leaks should be fixed as soon as possible.
Fuel System
When the diesel generator is running, check the entire fuel system including the fuel return path, filters and fittings for leaks, cracks or wear. Make sure that there is no friction and erosion of the fuel pipes and hoses with other parts and devices, and fix any leaks immediately, and change the route of the fuel lines to avoid the wear of the fuel supply pipes caused by collision with other equipment.
DC power system
Check the terminals of starter batteries for cleanliness and tight connections. Loose and sulfated connections cause electrical resistance that can make the diesel generator start process difficult. According to the NFPA 110 standard, the electrolyte level and voltage of the batteries should be checked weekly and maintained according to the manufacturer’s instructions. Defective batteries should be replaced as soon as the problem is identified. NFPA 110 recommends replacing batteries every 24 or 36 months.
Engine
Check fluid levels, oil pressure and water temperature regularly as most engine problems have an early warning. Pay attention to changes in engine performance and sound that indicate the need for repairs and service. Be aware of things like misfire, engine vibration, excess smoke in the exhaust, reduced engine power, or increased fuel or oil consumption.
Lubrication system
Check the engine oil level when the diesel generator is turned off. To better record the oil level through the oil indicator, it is better to wait 10 minutes after turning off the engine so that the oil in the cylinder head is drained into the crankcase. The choice of the used oil should be based on the viscosity index of the oil and according to the engine manufacturer’s proposal. If the oil level on the indicator is low, use oil of the same brand, fill the oil level as much as possible and up to the Full mark. Change the engine oil according to the engine maintenance schedule, and to do this, check the oil drain and filter replacement process with the manufacturer.
cooling system
When the diesel generator is off, check the radiator coolant level according to the maintenance schedule. After the engine has cooled down, open the radiator cap and if needed, add coolant (a mixture of water and antifreeze) to it so that the coolant level in the radiator is about 2 cm lower than the end of the radiator cap. Heavy duty diesel engines require a balanced solution of water, antifreeze and coolant additives for the radiator section. For coolant, it is recommended to follow the engine manufacturer’s recommendations. Check the outside of the radiator grill and clean the deposits and dirt on it with a soft brush or cloth, but be careful not to damage it while cleaning. If possible, you can use a low pressure air compressor or take the water flow hose against the air conditioning path in the radiator to clean it. You can also check its performance and correctness by checking the temperature of the coolant coming out of the heater.
Fuel System
Diesel fuel gets polluted over time and its quality decreases. One of the reasons for regular diesel generator tests is to consume stored diesel before it loses its properties. In addition to performing the services recommended by the manufacturer for the fuel system, diesel filters should also be replaced according to the schedule provided. Also, periodically, the water vapor condensed in the fuel source along with the sediments inside it should be discharged. Engine air intake pipes and hoses should be inspected daily for leaks, holes, cracks, or loose connections. The engine air intake cooling system (aftercooler) should also be checked for cracks, holes, and damage, and any dirt or clogging due to the presence of impurities in it should be removed. All components of the air intake path to the engine should be checked according to the schedule provided. The period of cleaning or replacing the air filter is determined based on the environmental conditions of the installation and operation of the diesel generator. Air filters usually have a paper cartridge that can be cleaned and reused if it is not damaged.
Starter batteries
The most common reason for an error in starting emergency diesel generators is weak or low-charge batteries. Even when fully charged and serviced, lead-acid batteries degrade over time and may not hold a charge and must be replaced periodically. A load test program and regular review based on a schedule can prevent problems caused by diesel generator starter faults. In the schedule of maintenance services, required inspections of batteries and their intervals are stated.
Battery test
To check the health of the battery, it is not enough to check its output voltage alone. Because with the passage of time, the internal resistance of the battery increases and the output voltage of the battery must be measured under load. In Cummins Power diesel generators that are equipped with the Power Command control system, this test (measurement of the battery voltage under load) is performed automatically every time the diesel generator is started. For other diesel generators, this test must be done manually with a battery tester.
Cleaning batteries
Always keep the batteries clean and remove dirt with a damp cloth. If the battery terminals are sulfated or rusted, open the battery cables and wash the terminals with a solution of water and baking soda (about 120 grams of baking soda per liter of water). You must be careful that the above solution does not enter the battery cells and after finishing this process, wash the batteries with clean water. After replacing the battery cable clamps, you can coat the battery terminals with some vaseline and then attach the battery clamps.
Checking the specific viscosity of the electrolyte
To check the specific viscosity of the electrolyte of each battery cell, you can use a hydrometer. The viscosity of a fully charged battery is numerically equal to 1.26. If the viscosity reading is less than 1.215, you need to charge the battery.
Checking the electrolyte level
You should check the battery electrolyte level at least every 200 hours of diesel generator operation. If the battery electrolyte is low, fill it with distilled water.
Diesel generator test
Emergency diesel generators must be able to be turned on in cold start mode and reach full load within a few seconds, which can impose severe mechanical and thermal stresses on the engine. Performing regular tests for the diesel generator lubricates the engine parts, prevents the oxidation of electrical connections, consumes the stored diesel before it loses its chemical properties, and in general helps to start the diesel generator safely. Turn on the diesel generator at least once a month and load it for 30 minutes in such a way that the actual output power is more than one third of the nominal power listed on the diesel generator plate. Also, the intervals between no-load operation of the diesel generator should be as short as possible because unburned fuel tends to accumulate in the exhaust system. If it is not possible to operate and test the diesel generator under normal load, you can use Load Bank to overload the diesel generator up to one-third of the active power listed on its nameplate, thereby increasing the performance and lifespan of the device.
