List of top Power Systems Questions

Match List I with List II

LIST I (Type of relay)		LIST II (characteristics)
A	Mho relay	I
B	Plain Impedance Relay	II
C	Directional relay	III
D	Angle Impedance Relay	IV

Choose the correct answer from the options given below:

Match List-I and List-II

LIST I		LIST II
A.	Thermal	I.	High operating cost
B.	Nuclear	II.	High capital cost
C.	Hydro	III.	High plant life
D.	Diesal	IV.	High fuel transtoortaicr cost

Choose the correct answer from the options given below:

Identify the location of fault in the power system shown in the figure below. A sustained 3-Φ fault occurred. (The voltage and current phasors, after the natural transients have died down are also shown.)

Two generating units rated for 250 MW and 400 MW have governor speed regulations of 6% and 6.4%, respectively, from no load to full load. Both the generating units are operating in parallel to share a load of 500 MW. Assuming free governor action, the load shared in MW, by the 250 MW generating unit is _________. (round off to nearest integer)

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