Year 2024

Week # 2 Quiz 4

Q1. A 3-phase star/delta connected transformer having a line voltage ratio of 440 V/11 kV is provided with Merz-Price circulating current protection. The protection transformer on 440 V side has a current ratio of 500/5. What should be the ratio of the protection transformer connected on 11 kV side? Assume that the line current on 440 V side is 500 A.

Q2. The inductance of transmission line is 1mH/km. If the spacing between conductors is made double the new inductance of line will be approx.

Q3. The zero-sequence network equivalent for the transformer connected between buses 1 and 2 as shown in Fig. is

Q4. In transmission line:

Q5. Murray loop test is performed on a faulty cable 300 m long. At balance, the resistance connected to the faulty core was set at 20 \(\Omega\) and the resistance of the resistor connected to the sound core was 40 \(\Omega\). Calculate the distance of the fault point from the test end.

Q6. If X is the system reactance and R its resistance, the power transferred is maximum when

Q7. A 183 bus power system has 150 PQ buses and 32 PV buses. In the general case, to obtain the load flow solution using Newton-Raphson method in polar coordinates, the minimum number of simultaneous equations to be solved is:

Q8. Fig. shows currents in a 3-phase conductor. The ends of the system on the sides of the fault are identified as F, F′, while the conductor ends are identified as aa′,bb′ and cc′. For one conductor open fault, the symmetrical components can be represented as

Q9. A 100 MVA, 11 kV, 3-phase, star connected generator has \(X_1\) = 35%, \(X_2\) =30%, \(X_0\) = 15% and feeds a line of \(X_1\) = \(X_2\) = 5% and \(X_0\) = 10%. The fault current for a 3-phase fault at line end is __________

Q10. For a power generation of \(300 MW\) in economic operation mode, the incremental cost is given by \((0.022 P + 12) Rs/MWh\) and plant penalty factor \(\lambda = 20\), then \(\frac{dP_L}{dP}\) incremental transmission loss is