By Jim Ellis & Lisa Phillips, Altorfer Power Systems
Power interruptions and power quality problems are an everyday occurrence.
Sources of these problems include heavy utility demands, lightning, fires, earthquakes, ice storms, auto accidents, short circuits, ground faults, human errors, and animals. Our 21st century digital society is more dependent than ever on a reliable source of quality electric power. With each passing year our demand for reliable electricity continues to grow, while power interruptions seem to occur more frequently. Power interruptions can cause los s of revenue, impair business operations — or worse — jeopardize human life and safety.
Every owner should understand the common reasons for emergency power system failure and should realize why proper maintenance will help prevent those failures. “A good maintenance program will consist of weekly, monthly, quarterly, and annual maintenance items” (NFPA 110). Owner personnel can perform many weekly maintenance items. But a qualified service provider can add great value by performing the higher-level maintenance required at the longer intervals. Qualified service providers are equipped with special tooling, have unique experience, and are trained to detect developing problems in mechanical equipment using their keen senses of sight, touch, and smell. The best service providers are able to offer solutions to satisfy all your needs, as a one safe source, alleviating the headache of dealing with multiple service providers. They can provide professional reporting and documentation to help assure that critical historical recordkeeping is maintained. Let’s take a look at ten of the most common problems encountered with power generation equipment in backup or emergency standby applications:
1. BATTERY SYSTEM PROBLEMS
“Analysis of emergency generator set failures shows that battery problems cause at least half of all failures to start” (Pocock).
Over-Extending Battery Service Life. Most battery failures are attributed to the buildup of crystalline lead sulfate on the battery’s lead plates (aka “sulfation”). This is a normal result of battery charging and discharging that worsens if batteries are not maintained at full charge. Batteries that are older, that have been through multiple charge/discharge cycles, or that have not been maintained at full charge must be replaced periodically. As batteries near the end of their service life, effective performance degrades more rapidly. “Batteries that are only providing 80% of the manufacturer’s capacity are considered to be at the end of their service life” (EGSA 100B). Proactive replacement of lead-acid type batteries every three years should be part of an overall maintenance strategy.
Lack of Routine Battery Maintenance. Routine maintenance is critical for best battery performance. Connections must be regularly cleaned and tightened. “A battery load test should be performed quarterly” (NFPA 110). It is necessary to monitor the electrolyte in wet lead-acid batteries. Charging depletes the water in the electrolyte, and topping up with distilled or deionized water is required — even under optimum conditions.
Battery Charger Malfunction. Modern generator set control systems continuously draw power from the generator set starting battery system. This power must be provided by the generator set static battery charger, or the starting batteries will soon discharge and fail to start the generator when needed. Frequently, battery failure is traced to an open or tripped battery charger circuit breaker. Over- or under-charging of batteries also creates problems. Incorrect charging can be caused by an improperly adjusted battery charger or possibly by an internal battery charger component failure. Proper operation of the battery charger’s float and equalize charge features should be verified routinely.
2. CONTROL SYSTEM PROBLEMS
Controls “Not in Auto”: Common issues related to generator set controls are simply not having the master control set for “Auto” (automatic) operation or mistakenly leaving the Emergency Stop Pushbutton depressed. After any activity is performed on or near a unit, always double check to assure that generator set controls are set for automatic operation.
3. COOLING SYSTEM PROBLEMS
Hoses and Belts: The most common cooling system problems are associated with deteriorating hoses and belts. Hoses on jacket water heaters are especially vulnerable and have a relatively short service life. Hose failure during a run cycle is very likely to cause serious engine failure due to a rapid loss of engine coolant. This risk can be minimized with timely proactive replacement of hoses. Drive belts should be regularly inspected for wear and correct tension. Applications with sets of multiple drive belts should be inspected when the machine is running to assure that all belts in the set are operating uniformly.
Plugged Radiator Core: A plugged radiator core, either externally with dust, oil, and debris or internally with corrosion and/or dirty coolant, will cause engine overheating. Radiators should be inspected regularly for any debris or dirt in or on radiator core, and the coolant should be monitored regularly to assure cleanliness and correct chemical composition. Engine cooling systems use distilled or de-ionized water mixed with antifreeze containing Supplemental Coolant Additives (SCA’s). The coolant mixture should be a minimum of 30% antifreeze to a maximum of 50% antifreeze, depending upon the freeze resistance required. Improper management of the coolant mixture properties can lead to internal radiator core and engine water jacket corrosion and scaling, coolant cavitation, and other harmful engine problems. A typical recommended cooling system service interval is every three years for engines in standby service. Engines with normal glycol-based coolant, should be drained, flushed, and filled with new coolant at this interval. For extended life coolant applications, an SCA booster package is added at the three-year mark, and the drain, flush and refill is performed at a six-year interval. Thermostats, drive belts, and coolant hoses should be replaced when the cooling system is drained and refilled. A coolant sample should be submitted for laboratory analysis on an annual basis to check for contamination and for proper condition of the coolant additives.
4. FUEL SYSTEM PROBLEMS
Contaminated Fuel. “It only takes six short months for diesel fuel to become jeopardized, thereby hindering generator performance and peace of mind when you need it most” (Wohlrab). Today’s high- performance diesel engines require a reliable and clean source of fuel. Water is the biggest enemy to diesel fuel and can be introduced from the supplier or simply from normal condensation within the fuel storage tank(s). Keeping tanks topped up with fuel and using fuel stabilizers can help to protect the fuel. When water contamination is present, bacteria or microbial growth in the tank is a threat. Microbial growth, sediment, and particulates can plug engine fuel filters causing a generator engine to starve for fuel. Water or moisture in fuel can damage diesel engines and can affect overall engine performance. A fuel sample should be taken semi-annually and inspected for discoloration and/or abnormal smell, both indications of water contamination and/or presence of organic debris. “A formal fuel quality test shall be performed at least annually using tests approved by ASTM standards” (NFPA 110). Alternatively, annual fuel polishing and tank cleaning are recommended to reverse the degradation process and restore and stabilize the overall quality of the fuel.
Out of Fuel. Nothing stops your standby generator set faster than running out of fuel. You should know how long the standby system will operate when the system tank(s) are full. Monitor the fuel level and calculate how long the system will operate with present fuel levels. Some generator set engines are equipped with “low level shutdown” or “critical fuel level shutdown” lockouts. This is to prevent the fuel system from drawing in air when running out of fuel is eminent. Avoid that sinking feeling in the middle of the night, and make your standby power system more reliable by having the fuel tanks topped up long before they reach empty.
5. AUTOMATIC TRANSFER SWITCH (ATS) OR SWITCHGEAR PROBLEMS
Controller Issue. Most ATS controllers today are micro-processor based. System settings, date, and timing functions are often maintained by a small backup battery. The most common preventable issue is a dead backup battery. Annual replacement of the backup battery is a low-cost preventative solution.
Dirt and Dust Accumulation. Dirt, dust and moisture can cause malfunctions in the transfer equipment. Dust should be removed annually by wiping and vacuuming. A small space (anti-condensation) heater can prevent accumulation of moisture inside equipment enclosures.
Loose Connections. Loose connections increase resistance, causing hot spots. Extreme cases can cause broken connections, short circuits, and even equipment fires. “It is recommended to check at a minimum annually for loose connections with the use of infra-red thermography during an emergency power system load test” (NFPA 110)
Mechanical Failure. Automatic transfer switches (ATS’s) and switchgear have moving parts. Moving parts can seize if they remain in one position for long periods of time. “It is best to ensure that moving parts will continue to operate smoothly with a monthly exercise that includes electrically operating the transfer switch with a loaded generator run” (NFPA 110). Performing actual outage tests that cause the ATS or switchgear to function will aid in exposing potential problems. Periodic lubrication of bearing points and inspection for electrical contact erosion are essential to good equipment health.
6. CIRCUIT BREAKER PROBLEMS
Breaker Trip Settings: Large circuit breakers have adjustable trip settings that must be set to match the loads they are to carry. In new installations or when existing loads have changed, it may be necessary to readjust circuit breaker trip settings to prevent nuisance tripping. This is particularly true when transformers make up all or a part of the circuit load, as a transformer can cause a current surge of up to twenty times its nameplate rating when first energized. Such current surges can easily cause nuisance tripping of incorrectly adjusted circuit breakers.
Maintenance: Reliable operation requires planned preventative maintenance. This includes cleaning, adjusting, lubricating, and testing circuit breaker(s). Annual inspection for loose connections is part of a comprehensive maintenance plan.
Open Circuits: Other common issues related to circuit breakers are failure to reset tripped breakers or leaving a circuit breaker in the open position. But if a breaker trip has occurred, be sure that the cause of the trip is determined and resolved prior to reclosing the breaker.
7. INTAKE/EXHAUST VALVE PROBLEMS
Like the human body, an engine must be able to inhale and exhale. Intake and exhaust valves control this process. Timing of the opening and closing, as well as the proper seal of these valves, is extremely critical to managing fuel economy and engine operating temperatures.
Improperly adjusted valves can fatigue and erode or fracture over time, often with tragic consequences. Debris from a valve failure can flow through the engine and cause damage to some of the most expensive components of the engine: cylinder liners, cylinder heads, turbochargers, pistons, and aftercoolers. Inspection and adjustment of valves and valve operators is recommended after an engine “break-in” period, usually at the first oil change, and then every two years for engines in standby service.
8. GENERATOR WINDING PROBLEMS
With all the attention being paid to an engine, one must not forget that the generator end of the machine also needs attention. Depending on the environment, generator windings can become coated with dust, dirt, oil, and grime. Daily temperature fluctuations, can allow moisture to condense on windings, in the same way that dew forms on windows of an automobile left outside overnight. Accumulated dirt tends to retain the moisture, and the combination can cause insulation breakdown, loss of insulation resistance, and possibly corrosion of winding metal itself. These, in turn, can lead to a short circuited or a grounded winding. When a generator is heavily loaded, the temperatures in the generator windings can exceed the boiling point of water, causing pockets of moisture to flash into steam. This action can result in a portion of the winding insulation being blown away, allowing a harmful path for electrical current. A costly failure or even life-safety issues can result. These types of failures can cost tens of thousands of dollars to repair, and can be avoided with proper maintenance. The root causes of these failures are rarely visible during a cursory inspection. A test of insulation integrity, such as the polarization index, can be used to evaluate the condition of the winding insulation and help determine if there is a harmful buildup of dirt or moisture in the windings. Insulation testing should be done at least annually to establish a trend. When test results indicate insulation deterioration, corrective action can be taken to avoid a major and costly breakdown.
9. LUBRICATION PROBLEMS
Bad things can happen to lubricating oil when an engine is operating, and bad things can happen to lubricating oil when an engine sits idle. A full service, including lubricating oil and filter change and a fuel filter change should be performed annually for generator sets in emergency standby service. Lubricating oil is the “life blood” of an engine, and it has a limited life inside of the engine. As the engine runs, the lubricating oil accumulates and binds contaminates, which could be harmful to the engine if not properly contained. Since standby systems rarely run for very many hours, they are especially vulnerable to the moisture and acids that form in the engine. These contaminates must be neutralized to prevent them from attacking bearings and engine wear surfaces. Operating an engine with contaminated lubricating oil can be very detrimental to engine components. Buildups of carbon and corrosive damage can occur, which can cause excessive bearing wear, crankshaft damage, wear surface seizure and other severe engine failure. Periodic lubricating oil and oil filter changes are very effective at preventing these problems and extending engine life.
10. WET STACKING & CARBON BUILDUP PROBLEMS
Diesel-powered generators are prone to problems associated with operating for extended periods of time with little or no load applied. This primarily results from over-sizing of the generator set to accommodate future loads and from maintenance test running that is necessary. Conditions such as accumulation of lubricating oil and unburned fuel in the exhaust stack (wet stacking) and carbon buildup in combustion chambers, on injector nozzles, piston rings, turbo chargers, exhaust piping and silencers commonly develop. “For total peace of mind, load banking is the method of choice to verify system operation, commissioning, and maintenance as well as certify system capacity” (Risser). An annual loadbank test at full generator set rated load will help prevent or regress these negative effects, will give owners renewed confidence in their equipment, and will prove proper operation of the entire generator set installation, including the starting system, the fueling system, and the ventilation and cooling systems. Annual load bank testing is required practice for hospitals and other critical applications. “Load bank testing should not be considered an option, but rather a critical element of your emergency preparedness plan” (Risser).
The common problems that can cripple an emergency standby power system are avoidable. Contact a qualified service provider and review your power system maintenance practices today. Be proactive! Do it now, before you’re left in the dark!
Association, Electrical Generating Systems. Performance Standard For Engine Cranking Batteries Used with Engine Generator Sets EGSA 100B. Standard. Boca Rotan, FL: Electrical Generating Systems Association, 1997.
NFPA. NFPA 110 Standard for Emergency and Standby Power Systems 2010 Edition. Standard. Quincy, MA: National Fire Protection Association, 2010.
Pocock, Roger. “Batteries and Battery Chargers.” Association, Electrical Generating Systems. On-Site Power Generation. Boca Rotan, FL: Electrical Generating Systems Association, 2002. 401.
Risser, Lyndon B. “Load Banking Best Practices.” Powerline July/August 2009: 20-23.
Wohlrab, Paul. “Peace of Mind Comes with a Price Tag.” Powerline September/October 2009: 30-31.
About the authors
Jim Ellis is the Product Support GM of Altorfer Power Systems, serving eastern Iowa, Central Illinois, and northeast Missouri. Jim has over 23 years of experience in the power generation industry. Altorfer Power Systems has a mission of being the undisputed leader in providing business solutions to its customers. They provide complete service and maintenance of engine-generators and associated electrical equipment from all manufacturers.
Lisa Phillips is the Electrical Testing Program Manager of Altorfer Power Systems. She spent four years in the United States Air Force. She graduated from Iowa State University with Bachelor of Science in Electrical Engineering degree, with emphasis on power engineering. Lisa worked for seven years at the Duane Arnold Energy Center, a nuclear power plant located in eastern Iowa, before accepting her current position with Altorfer. For the past four years at Altorfer, Lisa has been responsible for the Electrical Testing Program, which provides customers with maintenance and testing services of automatic transfer switches, generator controls, and switchgear.