Two 33 kV, 500 MVA three-phase generators with a reactance of 1.5 pu per phase are connected to a busbar (referred to as

[answerhappygod]

Two 33 kV, 500 MVA three-phase generators with a reactance of
1.5 pu per phase are
connected to a busbar (referred to as busbar A). Two identical
generators are connected to a
second busbar (referred to as busbar B). The two busbars are
connected via a bus-section circuit
breaker which is normally closed. A 100km long overhead three-phase
radial feeder is supplied
from busbar A via a 1000MVA, 33kV/275kV three-phase step-up
transformer with a reactance
of 10% per phase. A 100km long overhead three-phase radial feeder
is supplied from busbar B
via a 1000MVA, 33kV/275kV three-phase step-up transformer with a
reactance of 10% per
phase. The reactance of the overhead lines is 0.0378Ω per phase per
kilometre. All circuit
resistances may be assumed negligible.
a) Draw a one line diagram of the system described above.
b) Using a common base of 1000MVA, calculate the fault current that
would result from
a symmetrical three-phase short-circuit fault at the end of the
overhead feeder of busbar
A.
c) Calculate the fault level at busbar A.
d) Calculate the required reactance of a reactor to connect busbar
A to busbar B in order
to limit the fault level at busbar A to half of the normal
value.