Preventive maintenance for diesel engine generators plays a critical role in maximizing the reliability of these standby systems
Today’s electrical grid delivers reliable electricity to millions of homes and businesses. However, electrical failures that affect large geographic areas do happen on a recurring basis due to hurricanes, floods, or major equipment failures. Local outages that affect smaller numbers of people happen much more often. In fact, in 2012, there were more than 2,800 unplanned power outages in the United States that lasted an average of 2.5 hr. Combined, these affected more than 25 million people, according to Eaton Corp.’s “Blackout Training Annual Report 2012.”
For individual households, such power outages are often just an inconvenience. For hospitals and other health-care facilities, however, they can be life-threatening. For businesses like data centers, these outages can be extremely costly. A recent study by the Department of Energy found that financial losses from power outages at data centers ranged from $20,000 to $2 million per occurrence. Other mission-critical facilities at risk include government offices, police, fire, airports, and water/sewage treatment plants.
Having a well-designed and well-maintained standby power system is the best protection against utility power outages. According to the industry group Diesel Technology Forum, diesel-powered generators provide the most reliable form of emergency backup power, and can start/assume full-rated load in less than 10 sec. While backup generators typically can go 30,000 hr or more between major overhauls, even the best system needs to be exercised and maintained on a regular basis to make sure it operates properly when needed. When standby generators fail to start or perform as designed, it is usually due to faulty maintenance procedures or neglect. In fact, the top three reasons standby generators fail to automatically start or run are:
• The generator START switch was left in the OFF position instead of AUTO.
• Starting batteries were dead or insufficiently charged.
• The fuel filter was clogged due to old or contaminated fuel.
All of these common issues can be eliminated with a regular generator maintenance routine performed by properly trained personnel. Facilities with qualified in-house technical
personnel often can perform required preventive maintenance on diesel generators. Other facility managers prefer to contract with a local service provider or power system distributor for regular maintenance service, especially if they have generators in multiple locations.
Following is a list of maintenance procedures that need to be performed on a regular basis. In addition to these checks, exercising the power system under load on a weekly or monthly basis ensures that the generator set and its system of controls and transfer switches is operating as designed.
Because of the durability of diesel engines, most maintenance is preventive in nature and consists of the following operations:
• General inspection
• Lubrication service
• Cooling system service
• Fuel system service
• Servicing and testing starting batteries
• Regular engine exercise
It is generally a good idea to establish and adhere to a schedule of maintenance /service based on the specific power application and the severity of the environment. For example, if the generator set will be used frequently or subjected to extreme operating conditions, the recommended service intervals should be shortened accordingly. Some of the factors that can require more frequent maintenance include:
• Using the diesel generator set for continuous duty (prime power)
• Extreme ambient temperatures
• Exposure to weather
• Exposure to salt water
• Exposure to dust, sand, or other airborne contaminates
If the generator set will be subjected to some or all of these extreme operating conditions, it is best to consult with the engine manufacturer to develop an appropriate maintenance schedule. The best way to keep track of maintenance intervals is to use the running-time meter on the generator set to