Generator power rating guidelines

1. POWER RATING APPLICATION GUIDELINES
FOR
GENERATORS
These guidelines have been formulated to ensure proper application of generator drive engines
in A.C. generator set installations. Generator drive engines are not designed for and shall not be
used in variable speed D.C. generator set applications.
STAND BY PO WE R RATING is applica ble PR IM E POWER RATING is applicable for su p -
for supplying e mergency p owe r for the plying electric power in lieu of commercially
duration of the u tility powe r ou tage. No purchased po we r. Prime Power applications
overload capability is available fo r th is mu st be in the fo rm of one of the fo llow ing
rating. Under no condition is a generator two catego ries:
allowed to ope ra te in parallel w ith the
public utility at the S tand by Po wer UNLIMITED TIME RUNNING PRIME POWER
ra ting. Prime P ower is av ail able f or an unlimit ed number of
hours per year in a vari able load applic ati on. Variable
This rating should be applied where load should not exceed a 70% average of th e Prime
reliable utility power is available. A Power rating during any oper ating period of 250
standby rated engine should be hours.
sized for a maximum of an 80%
average load factor and 200 hours The tot al oper ating time at 100% Prim e P ower sh all
of operation per year. This includes not exceed 500 hours per year.
less than 25 hours per year at the A 10% overload capabilit y is available f or a period of
Standby Power rating. Standby 1 hour within a 12 hour period of operation. Total
ratings should never be applied operating tim e at the 1 0% overload power shall not
except in true emergency power exc eed 25 hour s per year.
outages. Negotiated power outages
contracted with a utility company LIMITED TIME RUNNING PRIME POWER
are not considered an emergency.
Prime P ow er is available for a limit ed n um ber of
hours in a non- variabl e load applicati on. It is intended
f or use in situati ons wh ere power out ages ar e
contr acted, such as in utilit y pow er curtailm ent .
Engin es may be o perated in parall el to the public
CONT INUOUS POWER RATING is utility up t o 750 hour s per year at power levels never
applicable fo r supplying utility power a t a to exc eed t he Prime Power rating. The cust om er
cons tant 100% load for an unlimited should be awar e, however, that the lif e of any engin e
nu mbe r of hou rs per year. No o ve rload will be r educed by this co nstant high load oper ati on.
capab ility is a va ilable Any operation exceeding 7 50 hours per year at t he
for this ra ting. Prime Power rating should use the Continuous Power
rati ng.
Reference Standards:
BS-5514 and DIN-6271 standards are based on ISO-3046.
Operation At Elevated Temperature And Altitude:
The engine may be operated at:
1800 RPM up to 5,000 ft. (1525 m) and 104 oF (40 oC) without
power deration.
1500 RPM up to 5,000 ft. (1525 m) and 104 oF (40 oC) without
power deration.
For sustained operation above these conditions, derate by 4% per 1,000 ft
(300 m), and 1% per 10 oF (2% per 11 oC).