What is the power rating? Prime vs standby power?

Generator sets are rated under two international definitions:

• PRP (Prime Rated Power) — for continuous or long-hour operation with variable load; average load factor may reach 70% of PRP.
• ESP (Standby Rated Power) — for emergency backup only; limited running hours, no overload capacity.

Ratings are expressed in kVA / kW at a power factor of 0.8 (1 kVA = 0.8 kW), together with allowable continuous running hours. Before selecting a unit, always confirm whether the application is prime or standby.