TP-7045 3/18c80 Appendix
Appendix C Generator Set Output Ratings Procedure
Kohler Co. develops the kilowatt output rating of a Kohlerr
marine generator set based upon the calculations
specified in ISO 3046 and ISO 8528-1. The calculations
correct for environmental variables encountered in a
generator set installation. Figure 1 outlines the
calculations. Figure 2 contains examples of how heat
variables affect generator set ratings.
Generator Output
corrected
= Generator Output
observed
x Correction Factor
Output power is expected to be within 5% of the specified rating when corrected to reference conditions.
Correction factors are determined using the following formulas:
1. For naturally aspirated compression-ignition engines (power limited by excess air):
C.F. = [1.175 (29.2 / Dry Barometer in. Hg)
1
(Temperature _F + 460/537)
.75
-- .175]
x Alternator Efficiency
Reference
/ Alternator Efficiency
Observed
2. For turbocharged compression ignition engines:
C.F. = [1.175 (29.2 / Barometer
Observed
in. Hg)
.7
(Temperature _F + 460/537)
2
-- .175]
x Alternator Efficiency
Reference
/ Alternator Efficiency
Observed
3. For turbocharged and intercooled compression ignition engines:
C.F. = [1.175 (29.2 / Barometer
Observed
in. Hg)
.7
(Temperature _F + 460/537)
1.2
-- .175]
x Alternator Efficiency
Reference
/ Alternator Efficiency
Observed
Reference conditions:
Temperature: 77_F; Pressure: 29.2 in. Hg dry barometer.
Kohler sound shield increases ambient intake air approx. 12_F
Approximate derates:
Temperature: approximately 1% per 10_F (turbocharged engines have a greater derate);
Pressure (altitude): approximately 4% per 1000 ft. (1 in. Hg)
Figure 1 Generator Output
Temperature (_F)
60 Hz
50 Hz
KEY
80 85 90 95 100 105 110 115 12077
Figure 2 Example: 6.5EFOZ/8EOZ kW Derates (ISO 3046/ISO 8258-1)
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