Preventive maintenance for generator set (genset) systems is an integral part of station operation. Engineers should do basic checks to ensure proper genset operation. The worst thing for a station is to discover that the genset does not work when it's needed most.
Figure 1 shows a functional block diagram of a typical genset system for reference in this discussion of preventive maintenance.
Functionally, a genset is mainly composed of a dynamo and its prime mover, an engine. The engine supplies the mechanical energy, and the dynamo turns it into electricity. Maintaining the engine is similar to maintaining that of a vehicle, while maintenance of the dynamo is the same as for an electric motor.
The battery provides power to the engine starter. It should be checked at least weekly for its capability to run the starter. Check the battery terminals to ensure that they make a good mechanical and electrical connection to the starter and the charger. Maintenance-free sealed batteries are the best to use, but lead-acid batteries can do the job at a lower cost. Just be sure to check the electrolyte levels of the lead-acid type on a monthly basis.
The coolant is usually composed of automotive-grade glycol to prevent freezing during winter. Check the level on the radiator on a regular basis, similar to what would normally be done on a car. Use a temperature gauge to ensure that the freezing point of the glycol mixture is much lower than what is required in the genset's location. Also, check the water hoses used on the engine for wear and cracks. Hoses can be deformed by old age and overheating, and they may need to be replaced before any serious leaks occur.
Inspect to ensure that clean air gets into the engine through the air filter. If the genset housing has a window with a louver intake, make sure that this louver opens when the genset is operating. The mechanical arm can sometimes become so stiff that there is not enough air coming into the genset building. Also, a screen should be installed to prevent the intake window from being clogged by insects. This screen should be inspected regularly to ensure free airflow.
Preserve the genset engine by keeping an eye on its engine oil. Use the right grade and check regularly for the proper oil level. The oil filter should be checked and replaced at the same time as the oil is changed. The engine manufacturer should have recommendations as to how often the oil and filter need to be replaced. Ensure that the cap of the dipstick is properly replaced after every inspection to prevent spillage during operation.
Depending on location, diesel is economical in the long run for big generator sets, while propane provides longer hours for smaller gensets. The hours of genset operation need to be logged at least weekly and the tank reservoir inspected. If using propane, check for leaks with soapy water and a sprayer at least weekly. Ensure that ice shields for any exposed part of the fuel piping are intact and can bear the brunt of ice storms in the area.
Have a genset dealer or representative do a load bank testing of the genset once a year. This may also include compression and timing tests to ensure that the engine is operating at optimum performance.
Mechanical parts of the ATS have a tendency to get stuck if not used regularly. Activate the automatic transfer switch (ATS) during a maintenance night to exercise it. Refer to the manufacturer's recommendations for proper lubrication of any moving parts. Use a laser-operated pyrometer to test connector temperature. This is particularly useful for determining if bolted connections for wires carrying high current are overheating. It enables the engineer to determine if the connection is overheating without making any physical contact with it, thereby making it a safe procedure.
The maintenance schedule
Table 1 is a suggested genset maintenance schedule. It is divided into frequency of implementation (weekly, monthly and annually). These frequencies may vary according to specific needs such as the age and size of the genset, its site location and available manpower. Develop a schedule that ensures optimum genset performance.
Rolin Lintag is an RF engineer in Little Rock, AR.