A generating station having 'n' section busbars each rated at Q kVA with ×% reactance is connected on the tie-bars systems through busbar reactances of b%. Determine the short circuit kVA if a 3-phase fault takes place on one section.

• A. Q[(1/x) + (n+1)/(bn+x)]
• B. Q[(1/x) + (n+1)/(bn-x)]
• C. Q[(1/x) - (n+1)/(bn-x)]
• D. Q[(1/x) + (n-1)/(bn+x)]

Answer: (D)

Short circuit kVA of any bus is given by:
Skva = Sbase*(100/% X)
Where,
Sbase - base rating in kVA
% X - value of reactance in %