Larger 480V wye Switchgear

this s where synchronisation of generators come....u need to learn abt tht.......

It is not easy to handle circuit breakers of more than 6000A and it is not commercially manufactured because of the BS/IEC Standard requirements. for such a system its better to put a tie breaker if the individual loads are not greater than 2400KVA, it is easy to synchronize and more cost effective.

Not clear for the " not greater than 2400KVA..."

You should not have put in a system larger than 8,000 KVA with 480 V. That system should have been at least 4160 V . If you do a cost benefit analysis, you'll see that. Did you have an Engineer design that system? You have great inefficiencies due to large copper conductors, you have very high short circuits, you have a very expensive gear, so, so ,so, on and on. Bad design. What to do now?

Best you can do is sectionalize the gear into separate, smaller units. If necessary, do a paralleling gear. A par. gear with dual end configuration can be made to work for 5,000 amps simply because if you put 2 gensets at each end, the entire gear won't see all current, it will spit to each end, thus you can size your CB's smaller. That's all I can say to you. Next time, before spending so much money, get a good Engineer, other wise your savings by not obtaining a good designer have already been more than gone...

By the way, I did not add that you need to do 100% rated 5000 A CB's. As far as I know that is the largest UL Listed CB made... With 2 100% rated 5000 A CB's you are realizing the full load of the generators. Simply because if you use std. cb's, they trip at 80% anyway and you get 9600 A, on a 12000 A system, this way, w/100% 5K CB's you realize full 10,000 A. You also need a tie breaker between the two ends of the gear. The loads should be equally distributed bet. the two sides... I did a system like that for a major co. except, it could take up to 8- 2500 KVA gensets because it was 4160!!