What is Prime Power?
Prime power is different than standby power. A generator rated for PRIME POWER is often 70-80% of the Standby power rating.
Prime power calculations are used in situation where a generator is the prime source or full time source of power. It is the ability of the generator to power a varying load for an unlimited number of hours per year. Just like in a standby generator, it too should have an average load not exceeding 70%.
Prime power ratings are smaller than Standby since the generator works much harder for longer periods of time rather than just emergencies. Some cases it is just for warranty purposes.