Three 45 MVA transformers are connected delta – delta to step down 13.8 kV to 4.16 kV. What is the three phase capacity of this bank? If one transformer fails and the bank is operated open delta what is the new three phase capacity?

Capacity all three __________

Capacity open delta __________

Ipri=45/(13.8x1.73)=1.89
Isec=45/(4.16x1.73)=6.25

Im kind of lost on this question if some one can help me solve this it would be greatly appreciated

 

We can't be of much help until you show some work so that we have someplace to start.

 

I got I pri and I sec so far

 

Could you at least draw a schematic of what the circuit looks like before and after the failure?