Selection of Bus Bar Rating

The current rating of one 30MVA Transformer at 11kV Side is about 1575 Amperes. For three transformers it would be 4725 Amps & for four transformers, this would be 6300 Amperes. If you have really provided only 2000 Amperes rated bus bars in the MV Panel, then in both the cases, your bus bars are insufficient. Pl. review your design.

May be they have separate busbars, for each transformer.

We don't know enough about your system, it appears you do not either. Maybe it is set up so that only one transformer is connected at any time, the others are redundant backups. Maybe the load is never more than 2000A, but has very large motors that need to start and there is a strict limit to any voltage drop so you need the high capacity on the system to meet that requirement. Too many unknowns. Ask the origibal designer, or if no longer available, hire a local professional electrical engineer that can observe the overall system.

http://cr4.globalspec.com/search/sitesearch?do=show&sort=textmatchrank&srch=bus%20bar%20rating&srchobjs=t%2Cc&fs=12&order=asc

you have to provide the single line diagram showing how the transformers are connected to the busbar and whether these are operating in parallel in order to size the busbar. If any standby transformer are there, then you have to indicate which is operating and which is standby.

You can manage with 2000 A busbar, provided the out goings are not bunched together.Each incomer section should have one outgoing with max of 2000 A.There should be four such incoming and four outgoings