======Prime Power vs Standby Power Ratings=====
Most generator sets are sold for "backup" power, to supply electricity when the utility power has failed. These are rated as "standby" generators, and while rated as "Continuous" duty -- meaning they will not overheat if used continuously -- this is an "emergency" rating, not a rating for long life of the generator end or engine.
"Prime Power" is the rating that should be used when a generator is to supply power in place of utility power, or in cases where it will supply power for significant portions of time on a regular basis when utility power is less than reliable.
We recommend purchasing generator sets based on the Prime Power ratings, even when they will be used for standby power in developing countries. This will result in longer life and better return on the investment.
====:: PRP :: Prime Power===
The prime power gen-set engine rating is the nominal power an
engine is capable of delivering with a variable load for an
unlimited number of hours per year with normal maintenance
intervals observed. This rating incorporates a 10% overload
capability which is available for up to 2 hours at a time.
Operating time between 100 % and 110% of the prime power
rating is not to exceed 8% of the total engine operating time.
This rating conforms to ISO 8528-1 "prime power (PRP)". The
permissible average power for the prime or PRP rating is not to
exceed 70% of rated prime power when calculated per ISO
8528-1.
====:: ESP :: Standby Power====
The standby gen-set engine rating is the nominal engine power
available at varying load factors for up to 200 hours per year
with normal maintenance intervals observed. No overload
capability is available for this rating. This rating conforms to ISO
8528-1 "Emergency Standby Power (ESP)". The permissible
average power for the standby or ESP rating is calculated per
ISO 8528-1.
====:: COP :: Continuous Power or Baseload Power ===
Applicable for supplying power continuously
to a constant 100% load for unlimited
hours. Continuous Power (COP) in
accordance with ISO 8528, ISO 3046,
AS 2789, DIN6271 and BS 5514.
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=====Power Rating Application Guidelines: Summary===
^ Power Rating ^ Normal Operating Mode Limitations ^^ Peak Operating Mode Limitations ^^ Typical Application ^
^ ::: ^ Maximum Average Load ^ Maximum Operating \\ Time per Year ^ Maximum Power ^ Maximum Operating\\ Time per Year ^ ::: ^
^ Standby Power | 80% of Standby Power | 200 hours | Standby Power | 25 hours | Emergency Standby |
^ Prime Power \\ - Unlimited Time - | 70% of Prime Power\\ (during any 250 hour \\ operating period) | Unlimited | (1) Prime Power + 10% | 25 hours | Unreliable Utility Power \\ Marine Auxiliary \\ Head-end equipment \\ Rental equipment |
^ ::: | ::: | ::: | (2) Prime Power | 500 hours | ::: |
^ Prime Power \\ - Limited Time - | 100% of Prime Power | 750 hours | Prime Power | 750 hours | Peak Shaving \\ Utility Power Curtailment |
^ Continuous Power | 100% of Continuous Power | Unlimited | Continuous Power | Unlimited | Utility Power \\ Electric Marine Propulsion \\ Cogeneration |