MV Fuses Protection for Delta Source, UG Cable Feeding SST Y Grounded

[cuky2000]

Can anyone advising how the fuses on the delta source protecting the downstream components against a fault.

DATA:
1) Fuses are CL, 25E, installed near the bushing of a Delta transformer.
2) Feeder: UG Solid dielectric cables 15 kV class, 133% Insulation level ( ≤1 min)
3) Load: Station Service transformer (SST) 300 kVA, 12.5 kV/7.2kV - 240/120 (Y Grd-Delta/ mid-tap grounded)

The estimated SLG fault at the source is 339A on the faulted phase and 50% in the healthy phase.

It appears that the fuse on the faulted phase will blow up first but not sure if the other two fuses will operate after that.

Below are a few more information collected from various contributors to this forum is pass threads.

 

[cuky2000]

The majority on the team believe that the fuses provide acceptable protection for the three-phase in the event of a SLG fault.

We are interested to know other opinions, please let us know.