MVA Method of Short Circuit Calculation

My analysis it should be computed separately independently, as in do your own homework

My analysis it should be computed separately but when i checked some sample in google they include the generator in fault contribution to the bus.

Funny that, being you are trying to calculate the short circuit current. Also funny when you consider that a downstream fault should operate the protection before the transformer changes over to to the generator hence the backup generator in parallel with the transformer won't be trying to feed the same short circuit the transformer was (which is pointless), regardless of the changeover scheme employed for the standby generator.

This really sounds like a homework question rather than a practical application in the real world.

Since the generator is connected to the utility power with the ATS (Automatic Transfer Switch), there is no possibility that the generator will run in parallel with the utility. In this case, you have to compute the short circuit separately. Out of the two separate studies, you need to consider the highest short circuit current value for the system design. However, if there is any possibility that the generator will run in parallel with the utility, you need to do the single study with both sources.

- MS

Thanks a lot Sir. Their is no chance that transformer & generator will run in parallel because of safety features installed both software & electro-mechanical . Now i have support of my theory to my boss.