1. The sequence component of phase a currents are: I_ao = 0 A; I_a1 = 10 + j5: I_a2 =8 - j5. Determine current in phase c.

2. The bus bars of a power station are in two sections A and B separated by a reactor. Connected in section A are two 12 MVA generators of 15% reactance each and to B, 8 MVA generator of reactance 10%. The reactor is rated 8 MVA and 15% reactance. Two feeders are connected to bus bar A through transformers, each rated at 4 MVA and 5% reactance. Determine the maximum short circuit MVA with which circuit breakers on the outgoing side of the transformers have to deal.

3. A 15 MVA, 6.6 kV, wye connected generator has X₁ = X₂ = 20% and X₀ = 10%. The neutral of the generator is grounded through a reactor of 5% reactance based on the generator rating. A double line-to-ground fault occurs at terminals b and c. What is the current in the ground?

4. Two generators rated 15 MVA, 30% reactance and 20 MVA, 50% reactance are connected to a common 12-kV bus bar. The percentage reactance of each generator is based on its own capacity. Determine the fault current if a symmetrical 3-phase fault occurs at the bus bar.

5. A 3-phase, 13.8 kV, 10 MVA alternator has positive, negative and zero sequence reactances of 0.20, 0.020 and 0.10 pu. Determine the fault current if a double line to ground fault occurs.