List of top Power Systems Questions asked in GATE Electrical Engineering

The fuel cost functions in rupees/hour for two 600 MW thermal power plants are given by \[ \text{Plant 1: } C_1 = 350 + 6P_1 + 0.004P_1^2 \] \[ \text{Plant 2: } C_2 = 450 + aP_2 + 0.003P_2^2 \] where \( P_1 \) and \( P_2 \) are the power generated by plant 1 and plant 2, respectively, in MW and \( a \) is constant. The incremental cost of power (\( \lambda \)) is 8 rupees per MWh. The two thermal power plants together meet a total power demand of 550 MW. The optimal generation of plant 1 and plant 2 in MW, respectively, are

Two balanced three-phase loads, as shown in the figure, are connected to a 100$\sqrt{3}$ V three-phase, 50 Hz main supply. Given \( Z_1 = (18 + j24) \, \Omega \) and \( Z_2 = (6 + j8) \, \Omega \), the ammeter reading, in amperes, is ________. (round off to nearest integer)

In the circuit shown below, a three-phase star-connected unbalanced load is connected to a balanced three-phase supply of 100\(\sqrt{3}\) V with phase sequence ABC. The star connected load has \( Z_A = 10 \, \Omega \) and \( Z_B = 20 \angle 60^\circ \, \Omega \). The value of \( Z_C \) in \( \Omega \), for which the voltage difference across the nodes \( n \) and \( n' \) is zero, is

The most commonly used relay, for the protection of an alternator against loss of excitation, is

The geometric mean radius of a conductor, having four equal strands with each strand of radius ‘r’, as shown in the figure below, is

The valid positive, negative and zero sequence impedances (in p.u.), respectively, for a 220 kV, fully transposed three-phase transmission line, from the given choices are