TP-5982 4/0662 Appendix
Appendix C Generator Set Output Ratings Procedure
General
Kohler Co. develops the kilowatt output rating of a
Kohler marine genset based upon the calculations
specified in ISO 3046 and ISO 8528-1. The calculations
correct for environmental variables encountered in a
genset installation. Figure 3 outlines the calculations.
Figure 4 contains examples of how heat variables affect
genset 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 spark-ignition engines using gaseous fuel:
C.F. = [1.175 (29.2 / Dry Barometer in. Hg)
0.86
(Temperature _F + 460/537)
0.55
− 0.175]
x Alternator Efficiency
Reference
/ Alternator Efficiency
Observed
2. For naturally aspirated spark-ignition engines burning gasoline:
C.F. = [1.175 (29.2 / Dry Barometer in. Hg)
1
(Temperature _F + 460/537)
0.5
− 0.175]
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 3 Generator Output
5.5
5.6
5.7
5.8
5.9
6.0
6.1
6.2
6.3
6.4
6.5
6.6
6.7
6.8
6.9
7.0
7.1
7.2
7.3
7.4
7.5
7.6
7.7
7.8
7.9
8.0
75 80 85 90 95 100 105 110 115 120
Temperature (_F)
77
60 Hz
50 Hz
KEY
Power Output
(kW)
Figure 4 Example: 8EOZ/6.5EFOZ kW Derates (ISO 3046/ISO 8258-1)
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