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Load Bank Testing- Essential Generator Maintenance

Chances are you don’t operate your generator at full power and full temperature unless you’re experiencing an emergency. In fact, your generator may not be used frequently or only run on light loads

 throughout the year leading you to believe it’s in fine shape. Plus, there’s that saying- “if it ain’t broke, don’t fix it.” The truth is, generators need annual load bank testing in their maintenance schedule for 4 key reasons: to ensure reliable operation during a power failure, to prevent ‘wet stacking,’ to extend the generator’s engine life and satisfy NFPA 110.

Reliable Operation in an Emergency

The last thing you want to find out in an emergency is that your standby generator cannot provide the full power you need from it. Load bank testing allows a standby generator to be tested and exercised to verify its overall reliability and its ability to run at its full rated kW output.

During the generator load test, a Duthie Power technician monitors critical engine parameters such as: oil pressure, engine temperature, fuel pressure, etc. These readings are recorded to show that once the unit reaches full rated load, it runs at normal operating temperatures and pressures.

Wet Stacking – As Dirty As It Sounds

Weekly no-load testing is how most generator owners exercise their standby generators. The problem with this practice is under-loading a generator can lead to ‘wet stacking’- when unburned fuel and soot accumulate in the engine exhaust. Wet stacking can manifest in black exhaust and pooling fuel oil, and it is damaging to the engine’s efficiency and life span. A buildup of wet stacking is also a fire danger.

Annual generator load testing allows the engine to reach its full operating temperature, so it burns out accumulated fuel and prevents wet stacking. This ensures the engine runs cleaner and more efficiently.

Extending the Generator’s Engine Life & NFPA 110

Whether your generator is diesel or gaseous fuel-driven, and whether it is run lightly loaded or never loaded at all, most manufacturers agree yearly generator load testing is a must to extend your engine’s life. In fact, it is not just a recommendation, it is required by the National Fire Protection Association (NFPA) for buildings and facilities with emergency or standby power supply systems (EPSS).

NFPA 110* is the set of standards and requirements for acceptance testing of EPSSs in buildings and facilities. NFPA 110 monthly generator load bank testing requirements include:

  • Test the entire EPSS
  • Run the generator under load
  • Exercise the Transfer Switches
  • Diesel Generators have a 30 minute minimum
  • For monthly testing, load to recommended exhausted temperature, or 30% of nameplate kW rating
  • Otherwise, perform an annual test using a supplemental load, for 30 minutes at 50%, 1 hour at 75%
  • For Level 1 Systems (Level 1 refers to a system in which failure of the equipment to perform could result in loss of human life or serious injuries):
    • 100% test for lesser of class duration or 4 hr, every 3 years, at 30% and at recommended exhaust temperature

Generator Load Bank Testing at Duthie

At Duthie Power Services, we offer generator load testing as a separate service. We can also structure it into a service contract to make it part of the yearly maintenance on your standby power system. Generator load testing is not intrusive in any way, and there is no interruption to your facility’s loads during the test. With a load bank tester, we provide a full report of the generator output readings for: voltages, amperages, kW amounts, and more.

We take pride in having served Southern California’s generator needs for over 50 years, and we understand the value of longevity. Contact our generator experts today to schedule your load bank test and ensure the longevity of your generator.

*NFPA 110 Reference-

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