Your emergency power system requires regular exercising under various loads to test the functionality of each of its components. Prime Power has load banks on hand that will handle wet stacking, diagnostics, and troubleshooting.Prime Power will also provide you with a full report of your equipment’s activity.
If your Emergency Power Supply System (EPSS) contains a Diesel-powered generator your equipment may develop a condition known as â€œwet stacking.â€ Wet stacking occurs when unburned diesel fuel escapes the engineâ€™s cylinders during the combustion cycle and accumulates in the exhaust pipes. Fuel can escape the cylinders when the combustion temperature and pressure is not high enough to adequately expand the piston rings and make a complete seal. Unburned diesel fuel in the exhaust system then becomes a fire hazard. Thereafter, once the system is operated under adequate load the exhaust will heat to a temperature high enough to ignite the fuel that has accumulated in the exhaust pipe creating a potentially disastrous fire. To prevent this from happening, the generator must be regularly operated under enough load to increase the combustion temperature inside the cylinders to seal the piston rings and burn off any unburned fuel that may have accumulated in the exhaust.
If your Diesel-powered generator does not perform under 30% of its nameplate kW rating load or greater during monthly test conditions, then your EPSS must be exercised once a year under artificial load.
Here are a few questions to help determine whether your equipment is in need of load banking:
- Each month, during your regular operating cycle, does your Diesel-powered generator operate at 30% of its nameplate kW rating or greater?
- If so, does the generator operate for at least 30 minutes at 30% or greater of its nameplate kW rating?
- If yes, then you may not need to perform load bank testing. Ask one of our technicians to do a complete evaluation of your system to determine its operability and efficiency.
- If no, then NFPA 110 states that you must exercise your emergency power system according to a prescribed method at least once per year.
- If your system does not operate at 30% or greater of its nameplate kW rating for at least 30 minutes each month, then your Diesel-powered generator will need to be â€œLoad Bankedâ€ and exercised under artificial load once per year.
The National Fire Protection Association (NFPA) prescribes when an EPSS is to be operated under sufficient loads, or through the use of a load bank, in its publication NFPA 110â€”Standard for Emergency and Standby Power Systems, 2005 Edition. After the load bank is attached to the generator, the generator must be run at 25% of nameplate rating for 30 minutes, followed by 50% of nameplate rating for 30 minutes, followed by 75% of nameplate rating for 60 minutes, for a total of 2 continuous hours. Exercising the equipment according to this schedule will simultaneously test the operating efficiency of the system and burn off any fuel that may have accumulated in the exhaust over the course of normal operating conditions.