GATE 2019: Power System Test 7

The single line diagram of a balanced power system is shown in the figure. The voltage magnitude at the generator internal bus is constant and 1.0 p.u. the p.u. reactance’s of different components in the system are also shown in the figure. The infinite bus voltage magnitude is 1.0p.u. A three-phase fault occurs at the middle of line 2.
The ratio of the maximum real power that can be transferred during the pre-fault condition to the maximum real power that can be transferred under the faulted condition is ______

A three–phase alternator generating unbalanced voltages is connected to an unbalanced load through a 3–phase transmission line as shown in Figure. the neutral of the alternator and the star point of the load are solidly grounded. The phase voltages of the alternator are: 

The positive sequence component of the load current is,
 

A three phase, 100 MVA, 25 kV generator has solidly grounded neutral. The positive, negative, and the zero sequence reactances of the generator are 0.2 pu, 0.2 pu, and 0.05 pu, respectively, at the machine base quantities. If a bolted single phase to ground fault occurs at the terminal of the unloaded generator, the fault current in amperes immediately after the fault is _________.

[Write the answer in nearest integer value]

A 3-phase transformer rated for 33 kV/11 kV is connected in delta/star as shown in figure. The current transformers (CTs) on low and high voltage sides have a ratio of 500/5. Find the currents i₁ and i₂, if the fault current is 300 A as shown in figure.