
224 Shipboard Electrical Power Systems
fault. Then, determine the fault current in amperes at the fault location and
also at the generator terminals using the voltage ratio.
(b) Repeat the calculation by converting the system on percent Z values based
on the kVA and voltage ratings of the generator, and then determine the
fault current in amperes at the generator and the transformer terminals, and
compare it with (a).
Gen
100 MVA, 3-ph
11 kV, X
d
˝ = 18%
(Not infinite bus)
25 MVA, 3-ph, 11/4.2 kV, Z = 7%
50 MVA, 11 kV
propulsion load
Other loads
SOLUTION
The generator in this example is not large enough to be treated as an infinite bus;
hence, it will ...