What is the difference between standby and prime duty?
A. Standby or emergency service is defined as usage during emergency power outages for the duration of the outage not to exceed 500-hours per year. This rating assumes that the load will be varied and intermittent as it is under normal utility applications. Prime power is defined as regular power used on a daily basis normally 8-12 hours per day which will typically exceed 500-hours per year. Prime duty is typically 10% less than the standby rating. Continuous duty is defined as 24-7 operation and is computed as 5% less than the prime duty rating. In addition to the generator duty ratings there are de-rates for altitude, high heat, and humidity which must be considered when calculating proper generator output.
