17. Attachment C Derating Calculation Sheet.pdf

Attachment C

Derating Calculation Sheet

89503220QWA000224

MEM RS22 C22N6 ONAN GENERATOR ALTITUDE DERATING CHART

Step 1

6690’ - 3300’ = 3390’

(AMSL OF SITE) - (First 3.3k’ of altitude) = (After subtracting first k’ of alt)

Step 2

22Kw * .04 = .88Kw

(Total power rating of generator) * (initial derating factor of 4%) = (4% of total rated P)

Step 3

22Kw - .88kW = 21.12kW

(Total rated P) - (4% of total rated P) = (first de-rated level)

Step 4

Each step from this point in the calculation should be sequential for each 1000’ increment for most accurate de-rated overall value.

3390’ - 1000’ = 2390’

(Remaining elevation) – (Next 1K’) = (Remaining elevation)

21.12kW * .04 = .8448kW

(New total rated P) * (derating factor of 4%) = (4% of total rated P)

21.12kW – .8448kW = 20.2752kW

(New total rated P) - (4% of total rated P) = (New de-rated level)

2390’ - 1000’ = 1390’

20.2752kW * .04 = .811kW

20.2752kW – .811kW = 19.464192kW

1390’ - 1000’ = 390’

19.464192kW * .04 = .77857kW

19.464192kW – .77857kW = 18.6856kW

1000’/390’ = 2.5641%

4% – 2.5641% = 1.4359%

18.6856kW * .014359 = .26831 kW

(New total rated P) * (derating factor of 4%) = (1.4359% of total rated P)

18.6856kW – .26831kW = 18.4173kW

< 3% of 1000’ and becomes insignificant

18.4173kW is estimated output for 22kW generator placed at this altitude