All of the ratings that are defined have a manufacturing tolerance of ± 3 percent.
Use the following guidelines in order to determine the applicable engine rating.
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Operating an engine at a greater power output than the engine is rated for will reduce the service life of the engine before overhaul. |
Ratings for Generator Set Engines
Load Factor - The sum of the loads divided by the number of hours of operation. Idle time and down time are not part of the calculation.
Power Interruption - Unexpected failure of the utility power supply.
Operating Cycle - Unless the operating cycle is specified differently, the operating cycle for calculating the load factors and the peak load limits is not to exceed 24 hours. The operating cycle does not include the time when the engine is not operating.
Continuous - This rating allows a constant load or a load that varies for an unlimited number of hours per year. The normal load factor is up to 100 percent for an unlimited number of hours per year. The following applications are suggested: base load, utility, cogeneration and parallel operation.
Prime - This rating allows a load that varies for an unlimited number of hours per year. The normal load factor is up to 80 percent for an unlimited number of hours per year. A 100 percent load is only allowed for 5 percent of the operating cycle. The following applications are suggested: industrial, pumping, construction and cogeneration.
Prime + 10% (Standby applications for a power supply from a reliable utility) - This rating allows a load that varies up to the Prime rating. An additional 10 percent is allowed for the duration of the power interruption. The normal load factor is up to 80 percent for 100 hours per year. A 100 percent load is only allowed for 5 percent of the operating cycle. The suggested application is Standby for a power supply from a reliable utility.
Prime + 10% (Applications that are industrial, pumping, construction, and cogeneration) - This rating allows a load that varies up to the Prime rating. The normal load factor is up to 80 percent for an unlimited number of hours per year. A load of 100 percent is only allowed for 5 percent of the operating cycle. The following applications are suggested: industrial, pumping, construction and cogeneration.
Standby - This rating allows a load that varies for the duration of the power interruption. The normal load factor is up to 80 percent for 100 hours per year. A 100 percent load is only allowed for 5 percent of the operating cycle. The suggested application is Standby for a power supply from a reliable utility.
Load Management Peak Shaving Rating Guidelines
Interruptible (Isolated from the utility with a Standby base rating for load factors) - This rating allows a load that varies for less than 12 hours per day. The typical peak load factor is up to 80 percent for less than 500 hours per year. The peak operating limit is a load factor up to 100 percent. A 100 percent load is only allowed for 5 percent of the operating cycle. The operating cycle for calculating the load factors and the peak load limits is not to exceed 6 hours. The operating cycle does not include the time when the engine is not operating.
Interruptible (Isolated from the utility with a Prime base rating for load factors) - This rating allows a load that varies for more than 12 hours per day. The typical peak load factor is up to 80 percent for an unlimited number of hours per year. The peak operating limit is a load factor up to 100 percent. A 100 percent load is only allowed for 5 percent of the operating cycle.
Curtailable (Connected to a utility with a special base rating for load factors) - This rating allows a constant load or a load that varies for less than 6 hours per day. The typical peak load factor is up to 100 percent for a maximum of 500 hours per year. The peak operating limit is up to 100 percent load for a maximum of 500 hours per year.
Curtailable (Connected to a utility with a Continuous base rating for load factors) - This rating allows a constant load or a load that varies for more than 6 hours per day. The normal load factor is up to 100 percent for an unlimited number of hours per year. The peak load factor is up to 100 percent for an unlimited number of hours per year.