Prime power rated generators should be used in applications where the user does not purchase power from a public utility. Prime power applications fall under two distinct categories:
Indefinite Running Time
The prime power rating is the maximum power accessible at the variable load for an unlimited number of hours per year in a variable load setting. It is not advisable that the variable load exceed 70% average of the prime power rating during any operational period of 250 hours. If the engine is running at 100% prime power, yearly hours should not exceed 500. Overload situations should be avoided however a 10% overload capability is available for a 1 hour period within a 12 hour cycle of operation.
Prime power is accessible for a limited number of hours in non-variable load situations. Limited prime power is intended for circumstances where power outages are expected, such as a planned utility power reduction. Engines in generator sets may operate up to 750 hours per year at power levels less than the maximum prime power rating. In these situations it is important to never exceed the prime power rating. The end user should be aware that constant high load use will reduce the life of any engine. It is recommended that any application requiring over 750 hours per year that the engine be continuous power rated.
Continuous Power Rating
Continuous power rating is used in applications where supplying power is at a constant 100% load for an unlimited number of hours each year. Continuous power rated units are most widely used in applications where the power grid is unreachable. Such applications include mining, agriculture or military operations.