25.3 kV Nominal Rating GCB Applied to 26 kV Nominal Validation

[Optimus Prime]

HI all, I would like to obtain technical insights from the technical community about a GCB application that we will have in which: rated nominal and maximum generator voltages are 26 KV and 27.3 kV. The offered GCB breaker is having a nominal rated voltage of 25 kV.

The manufacturer performed TRV calculations based on fault current values (Generator Contribution and System Utility Contributions). Based on TRV calculations, they are claiming that their 25 kV rated breakers will be able to withstand a nominal voltage of 26 kV and a maximum voltage of 27 kV. Is this a valid way to verify the application?

Does this mean also that the GCB insulation would be able to withstand 26-27 KV continuously?

 

[Optimus Prime]

Please find attached Breaker Rated Values and the TRV comparison between rated and calculated.

 

[Kiribanda]

1) Per IEEE C37 for nominal system voltage of 25kV the maximum voltage of the CB should be 27kV where max. voltage is for which the CB is designed for. Therefore, if the quoted CB is designed, manufactured & tested for C37 then the CB rating plate should show the "Rated Max. Voltage" =27kV. I cannot see that info in the attachment.
2) What is the application of this CB? Is it going to be in a 25kV indoor swgr line up or otherwise? Because for TRV studies in an EMTP software, typically the incoming line must be modeled at least for 2 spans because it is a L,R,C system which oscillates. Have you seen their TRV study report?
3) What is your SLD please?