I've been tasked with checking to see if an existing backup generator will be powerful enough to handle a new building in addition to the buildings it is currently handling.
First, here is the details I got off the nameplate of the generator:
Name: Olympian Model: GEH275 Rated Power - Prime: 250.0 kVA 200.0 kW 0.80 COS θ Rated Voltage: 415/240 V Phase: 3 Rated Frequency: 50 Hz Rated Current: 348 A Maximum Ambient Temp: 27 *C (There is a note that it can go up to 50 *C but will affect outputs and that the manufacturer should be contacted)
The new building will have 33 AC units which will be the primary power consumers. Here is the details I found on the AC labels:
Phase: 1θ Frequency: 50Hz Voltage: 230V Cooling Capacity: 6448 W Normal Input: 2149W Normal Current: 9.8A Max Input: 3733 W Max Current: 20.6A
I checked the generator panel at different times during the day, and this is the highest reading I ever got off of it:
AVG: 415 V L-L 100A 50.0 Hz L-L: 413V/136A, 418V/72A, 415V/89A L-N: 239V/136A, 240V/74A, 241V/89A
My understanding of the above is that I am current using:
239*136 + 240*74 + 241*89 = 71.713 kVA
This represents 71.713/250 = 28.7% of the total kVA possible
According to the AC labels they are normally operating at 9.8*230 = 2.254kVA and they peak at 20.6*230 = 4.738kVA. 33 of these units will be running at 67.62 kVA and peak at 142.15 kVA.
If the ACs all turn on at the same time, the generator will need to supply 142.15 + 71.713 = 213.82 kVA which works out to 85.5% total kVA. During normal AC operation the total should be 55.7% total kVA.
I am not sure what I should be doing with the power factor information. Should I be working in kW and using the total of 200.0 kW? I am also wondering how much the ambient temperature can affect things. The ambient temperature where we are operating this generator is regularly above 40*C