Q. The number of roots of the polynomial, 𝑠7 + 𝑠6 + 7𝑠5 + 14𝑠4 + 31𝑠3 + 73𝑠2 + 25𝑠 + 200, in the open left half of the complex plane is (A) 3 (B) 4 (C) 5 (D) 6 Ans: 3

Q. The equivalent impedance Zeq for the infinite ladder circuit shown in the figure is (A) j12 Ω                    (B) –j12 Ω                  (C) j13 Ω                   (D) 13 Ω Ans: j12Ω Sol:

Q. A DC voltage source is connected to a series L-C circuit by turning on the switch S at time t = 0 as shown in the figure. Assume i(0) = 0, v(0) = 0 . Which one of the following circular loci represents the plot of i(t) versus v(t) ? Ans: Option B

Q. The per-unit power output of a salient-pole generator which is connected to an infinite bus, is given by the expression, 𝑃 = 1.4 sin 𝛿 + 0.15 sin 2𝛿, where 𝛿 is the load angle. Newton- Raphson method is used to calculate the value of 𝛿 for 𝑃 = 0.8 pu. If the initial

Q. Consider the two bus power system network with given loads as shown in the figure. All the values shown in the figure are in per unit. The reactive power supplied by generator G1 and G2 are QG1 and QG2 respectively. The per unit values of QG1, QG2, and line reactive power loss (Qloss) respectively

Q. The positive, negative and zero sequence impedances of a three phase generator are 𝑍1, 𝑍2 and 𝑍0 respectively. For a line-to-line fault with fault impedance 𝑍𝑓, the fault current is 𝐼𝑓1 = 𝑘𝐼𝑓, where 𝐼𝑓 is the fault current with zero fault impedance. The relation between 𝑍𝑓 and 𝑘 is Ans: Option A Sol:

Q. A 0-1 Ampere moving iron ammeter has an internal resistance of 50 mΩ and inductance of 0.1 mH. A shunt coil is connected to extend its range to 0-10 Ampere for all operating frequencies. The time constant in milliseconds and resistance in mΩ of the shunt coil respectively are (A) 2, 5.55                  (B) 2,

Q. A separately excited dc motor has an armature resistance 𝑅𝑎 = 0.05 Ω. The field excitation is kept constant. At an armature voltage of 100 V, the motor produces a torque of 500 Nm at zero speed. Neglecting all mechanical losses, the no-load speed of the motor (in radian/s) for an armature voltage of

Q. A 1000 × 1000 bus admittance matrix for an electric power system has 8000 non-zero elements. The minimum number of branches (transmission lines and transformers) in this system are (up to 2 decimal places). Ans: 3500 Sol:

Q. The positive, negative and zero sequence impedances of a 125 MVA, three-phase, 15.5 kV, star-grounded, 50 Hz generator are 𝑗0.1 pu, 𝑗0.05 pu and 𝑗0.01 pu respectively on the machine rating base. The machine is unloaded and working at the rated terminal voltage. If the grounding impedance of the generator is 𝑗0.01 pu, then