pad mounted transformer protection 1

[EEuno]

I have a 300 KVA Westinghouse Pow-R-Pad oil filled transformer with current limiting fuse canisters visible in the primary voltage section of the transformer. The nameplate on the transformer, per phase, indicates two (2) fuses in parallel connected to a third fuse in series. This then connects to a delta primary winding. Why the three (3) fuse depiction, per phase conductor, nine (9) fuses total?

 

[davidbeach]

No idea about the parallel fuses on a transformer that small. The fuses in series have rather different characteristics and the series combination gives you the best of both, one is providing the fault limiting and interrupting while the other is longer term overload protection.