TP-6069 6/03A-4 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
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
Figure 2 Example: 6.5EFOZ/8EOZ kW Derates (ISO 3046/ISO 8258-1)
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