UPSC Electrical Engineering 2021

(a) In Figure 1(a) shown below, the two-port network is characterized in terms of y-parameters with y₁₁ = 3·3 × 10⁻³ S, y₂₂ = 5 × 10⁻³ S and y₁₂ = y₂₁ = 0. Find the voltage across…

(a) Find the Thevenin's equivalent of the circuit shown in Figure 2(a) below as seen from the load impedance Z_L. Also find the value of Z_L for maximum power transfer. (20 marks)…

(a) (i) Explain what happens when a circuit shown in Figure 3(a)(i) below is constructed using logarithmic amplifier. 10 Figure 3(a)(i) (ii) Explain what happens if the topology i…

(a) Consider a discrete time system with transfer function given by H(z) = Y(z)/R(z) = (z⁻¹ - ½z⁻²)/(1 - z⁻¹ + 2/9 z⁻²). Calculate the following : (i) The impulse response of the…

(a) A step down dc chopper is feeding a load of R = 10 Ω and L = 20 mH. The dc supply voltage is 100 V. The chopper is switching at a frequency of 2 kHz with a duty cycle of 50%.…

(a) The magnetic field intensity of a linearly polarized uniform plane wave propagating in the +Y-direction in sea water (ε_r = 80, μ_r = 1, σ = 4 S/m) is H = 0·1 sin (10^10 πt -…

The following test data are obtained for a three-phase, 195 MVA, 15 kV, 50 Hz star connected synchronous machine. Open circuit test : | I_f (A) | 150 | 300 | 450 | 600 | 750 | 900…

For an FM communication system with β = 2 and white channel noise with PSD Sₙ(ω) = 10⁻¹⁰, the output SNR is found to be 28 dB. The base band signal m(t) is Gaussian, band-limited…

(a) A system is described by the following state equations : dotx₁ = x₁ + x₂ + 3x₃ dotx₂ = 2x₁ + 3x₂ + u₁ dotx₃ = 2x₂ + x₃ + u₂ Check the controllability of the system. (10 marks)…

(a) Draw the sequence networks and calculate the load sequence impedances of a load circuit as shown in figure. The load circuit is connected to a balanced three phase supply. The…

3.(a) A solidly earthed 400 KV, 3 phase busbar system is connected with two incoming and four outgoing lines (feeders). A differential protection is provided with switchgear of 40…

4.(a)(i) The configuration of a 400 KV 3 phase line is shown in figure. The radius of each sub-conductor is 2 cm. Calculate the charging mega volt-amperes if line is operating at…

(a) Explain the ratio error and phase angle error of current transformer. 10 marks (b) The two top rows of a Routh table of a characteristic polynomial is given in the table. Dete…

(a) A synchronous machine is connected to an infinite bus through a transformer and a double circuit line as shown in figure. The infinite bus voltage is V = 1·0 ∠0° p.u. The dire…

(a) Discuss the percentage differential Relay with harmonic restraint with the help of diagram and also draw the conceptual representation of it. (20 marks) (b) A sinusoidal volta…

(a)(i) Prove that the minimum distance of any linear (n, k) block code satisfies dmin ≤ 1 + n – k. (5 marks) (a)(ii) Show that the minimum Hamming distance of a linear block code…