Service Manual

6. Service10-2019
115A062J683 (Issue 1) Copyright © 2019 Cummins Inc.
Factor Values
Derate for
Elevation
Operating Elevation - Rated Elevation =
Total ft Above Rated
2750 ft – 1000 ft
=
1750 ft
Total ft Above Rated/1000 ft =
Elevation Ratio
1750/1000 = 1.75
Elevation Ratio x Derate Schedule =
% Reduction of output from Elevation
(Elevation Reduction)
1.75 x 3.5% = 6.1%
Derate for
Temperature
Operating Temperature - Rated
Temperature =
Total °F Above Rated
93 °F – 77 °F = 16 °F
Total °F Above Rated/10 °F =
Temperature Ratio
16/10 = 1.6
Temperature Ratio x Derate Schedule =
% Reduction of Output from Temperature
(Temperature Reduction)
1.6 x 3% = 4.8%
Total Derate
Elevation Reduction + Temperature
Reduction =
Total Reduction
6.1% + 4.8% = 10.9%
Total Reduction/100 =
Decimal Percent Reduction
10.9/100 = 0.109
Total Watts x Decimal Percent Reduction =
Expected Power Reduction
17,000 x 0.109 = 1,853 Watts
Total Watts - Expected Power Reduction =
Expected Power
17,000 – 1,853 =
15,147
Watts
Total Amps x Decimal Percent Reduction =
Expected Current Reduction
70.8 x 0.109 = 7.7 Amps
Total Amps - Expected Current Reduction =
Expected Current
70.8 – 7.7 = 63.1 Amps
* This schedule is for the C17N6H model only. See the Model Specifications section for
generator set derating guidelines for all models.
Windings
Introduction
NOTICE
Disconnect all control wiring and customer load leads from alternator
winding connections before conducting these tests.