3208 INDUSTRIAL AND GENERATOR SET ENGINES – Engine Ratings

Rating Conditions
Unless otherwise specified, all ratings are based on SAE J1349 standard ambient conditions:

* 100 kPa (29.6 inches of Hg) of pressure
* 30 percent relative humidity
* a temperature of 25°C (77°F)
Ratings also apply at AS1501, BS5514, DIN6271, ISO3046/1 standard conditions and off-road emissions ISO8178.

Power for diesel engines is based on:

* API gravity of 35 at 15°C (60°F)
* fuel LHV of 42.780 kJ/g (18390 Btu/lb) at 29°C (84°F)
* fuel density of 839 g/L (7 lb/US gal)
Ratings are gross output ratings- the total output capability of the engine equipped with standard accessories. Standard accessories include pumps for lubrication oil, fuel, and jacket water as required. The gross output, minus the power required to drive auxiliary components, equals the net power available for the external (flywheel) load. Typical auxiliary components include cooling fans, air compressors, and charging alternators.

Ratings must be reduced to compensate for altitude conditions, according to the applicable engine test specification derating data at normal ambient temperature.

NOTE: The application examples are listed for reference only. Refer to the specific application information and guidelines within the Technical Marketing Information for exact rating determination.

Industrial Rating Definitions

A Rating (Continuous)
* For heavy-duty service when engine is operated at rated load and speed up to 100 percent of the time without interruption or load cycling.
* Time at full load up to 100 percent of the duty cycle.
* Typical examples are: pipeline pumping, ventilation, and customer specifications.

B Rating
* For service where power and/or speed are cyclic.
* Time at full load not to exceed 80 percent of the duty cycle.
* Typical examples are: irrigation where normal pump demand is 85 percent of the duty cycle, oil field mechanical pumping and drilling, and stationary/plant air compressors.

C Rating (Intermittent)
* For service where power and/or speed are cyclic.
* The horsepower and speed capability of the engine can be used for one uninterrupted hour, followed by one hour of operation at or below the A rating.
* Time at full load not to exceed 50 percent of the duty cycle.
* Typical examples are: agricultural tractors, harvesters and combines, off-highway trucks, fire pump application power, blast hole drills, rock crushers and wood chippers with high torque rise, and oil field hoisting.

D Rating
* For service when rated power is required for periodic overloads.
* The maximum horsepower and speed capability of the engine can be used for a maximum of 30 uninterrupted minutes, followed by one hour of followed by one hour of C rating operation.
* Time at full load not to exceed 10 percent of the duty cycle.
* Typical examples are: offshore cranes, runway snow blowers, water well drills, portable air compressors, and fire pump certification power.

E Rating
* For service where rated power is required for a short time for initial starting or sudden overload. For emergency service where standard power is unavailable.
* The maximum horsepower and speed capability of the engine can be utilized for a maximum of 15 uninterrupted minutes, followed by one hour at C rating operation, or for the duration of the emergency.
* Time at full load is not to exceed 5 percent of the duty cycle.
* Typical examples are: standby centrifugal water pumps, oil field well servicing, crash trucks, and gas turbine starters.

Generator Set Engine Ratings
All ratings shown are subject to manufacturing tolerances of plus or minus three percent.

Standby Rating
* Typical load factor: 60 percent or less.
* Typical operating hours per year: 100 or less.
* Typical peak demand: 80 percent of the Standby rated kW, with 100 percent of the rating available for the duration of emergency outage
* Typical Application: Building Service Standby within an enclosed sheltered environment

Prime Plus 10 Percent Rating
* Typical load factor: 60 percent or less.
* Typical operating hours per year: 500 or less.
* Typical peak demand: 80 percent of the Prime Plus 10 Percent rated kW, with 100 percent of the rating available for the duration of emergency outage.
* Typical applications: Standby, Rental Unit, Power Module, Unreliable Utility, and Interruptible Rates.

Prime Rating
* Typical load factor: 60 to 70 percent.
* Typical operating hours per year: no limit.
* Typical peak demand: 100 percent of the Continuous rated output is used for less than 10 percent of the operating hours.
* Typical applications: Industrial, Pumping, Construction, Peak Shaving, and Cogeneration.

Continuous Rating
* Typical load factor: 70 to 100 percent.
* Typical operating hours per year: no limit.
* Typical peak demand: 100 percent of the Continuous rated kW is used for less than 100 percent of the operating hours.
* Typical application: Base Load, Utility, and Cogeneration.

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