GENERATOR AIC RATING

[Toros]

Hi,
We have to install panels for three warehouses in a desert where no utility SCE is available
using gas generator
if we want to use series rating method,
what is the AIC of main in that generator????

thank you

 

[kwired]

Hi,
We have to install panels for three warehouses in a desert where no utility SCE is available
using gas generator
if we want to use series rating method,
what is the AIC of main in that generator????

thank you

AIC applies to the switches/overcurrent devices.

What you likely want to know the available fault current - this will depend on kVA rating of the unit and impedance of the windings, just like it does for a utility supplied transformer as well as some details on the prime mover. Generally it should be less then it will be for a similar kVA utility transformer though unless it has a well oversized prime mover.

 

[Ingenieur]

here's a brief description
you need the subtransient reactance pu X''
http://apps.geindustrial.com/publib...ircuit?TNR=White Papers|Short Circuit|generic

basically
i sc =i rated / X'' pu

many time the mfg will give the sc i in their data

working on a side project for a sr citizen hi-rise genset upgrade
100 kw/ 125 kva 120/208, rate i 347 A
no X" in the data
it does say 300% sc i for 10 sec ~ 1050 A

starting kva 448 (360%) or at 35% v drop
i = 448000/(sqrt3 x 0.65 x 208) = 1915 A
~X" = (0.65 x 208)/1915 = 0.0707 Ohm 3 ph, 1 ph 0.0408
X base = (208^2)/125000 = 0.3461
~X" pu = 0.0707/0.3461 x 100 ~ 20.7%

but moot, much smaller than the feeder

I'll use the 1915 if I can't obtain an X" value from the mfg

 

[Ingenieur]

math error
the 0.0707 needs adjusted for 208 from the 35% v drop
~ 1/0.65 x 0.0707 = 0.109 3 ph, 0.0628 1 ph
pu = 0.0628/0.3461 ~ 18.14 %

i rated/pu X" = 347/0.1814 = 1915

 

[kingpb]

Hi,
We have to install panels for three warehouses in a desert where no utility SCE is available
using gas generator
if we want to use series rating method,
what is the AIC of main in that generator????

thank you

Without a single line diagram and idea on equipment sizes/ratings it is not practical to offer the information you are looking for. Can you post a SLD of what the system will look like?