Electrical Engineering

UPSC Electrical Engineering 2023

All 16 questions from the 2023 Civil Services Mains Electrical Engineering paper across 2 papers — 800 marks in total. Each question comes with a detailed evaluation rubric, directive word analysis, and model answer points.

16Questions
800Total marks
2Papers
2023Exam year

Paper I

8 questions · 400 marks
Q1
50M Compulsory solve Network analysis, signals and systems, machines, electronics, and electromagnetics

(a) Obtain Norton equivalent circuit at terminals ab of the coupled circuit shown in the figure. Using it, find out the current passing through 5 Ω resistor connected between the…

Q2
50M solve Network analysis, digital signal processing, and analog electronics

(a) For the circuit shown in the figure, obtain the value of voltage across 0·5 Ω and 2·5 Ω resistors using nodal current analysis. (20 marks) (b) A causal discrete-time LTI syste…

Q3
50M solve Digital electronics, signals and systems, operational amplifiers

(a) (i) Consider the shift register shown in the figure below, which is implemented using D flip-flops and 2 : 1 multiplexers. Complete the truth table shown as follows: | Inputs…

Q4
50M solve BJT circuits, digital logic design, two-port networks

(a) For the circuit shown below, early voltage V_A = ∞ and β = 100. Find the reverse saturation current if: (i) the collector current of Q₁ = 0·5 mA. (ii) Q₁ is biased at the edge…

Q5
50M Compulsory solve Synchronous motor, converters, AM signals, transmission lines, RLC circuits

(a) A 400 V, 50 Hz, 3-phase star-connected cylindrical rotor synchronous motor has synchronous impedance of (0·5 + j 2·5) Ω per phase. It develops a maximum power of 50 kW at rate…

Q6
50M solve DC machines, electromagnetic wave absorption, rectifier-fed DC motor speed control

(a) A 200 V, 1100 rpm, dc shunt motor takes 1·5 A and runs at 1150 rpm under no load condition at rated voltage. Its armature resistance including brushes is 0·5 Ω. While running…

Q7
50M calculate Synchronous machines, probability, power electronics

(a) A 400 V, 3-phase, 50 Hz, star-connected synchronous motor has per phase synchronous impedance Zₛ = (0·5 + j 3·5) Ω. It is required to operate the motor as synchronous condense…

Q8
50M calculate Induction motor drives, communication systems, transformers

(a) A 415 V, 4-pole, 3-phase, 50 Hz, star-connected squirrel cage induction motor has per phase parameters of r_s = 1·1 Ω, r_r = 1·3 Ω, X_m = 167 Ω, and X_ls = X_lr = 3·5 Ω, all a…

Paper II

8 questions · 400 marks
Q1
50M Compulsory solve Control systems, circuit breakers, PCM, microprocessor, transmission lines

(a) The figure shows a unity feedback system with open-loop transfer function G(s) = K/((s + 1)(s + 2)). The steady-state value of the unit step response c(t) is 0·8. Determine th…

Q2
50M solve Root locus, Schering bridge, delta modulation

(a) The block diagram of a feedback system is shown in the figure: the forward path is G(s) = K/((s − 1)(s² + 4s + 7)) and the feedback path is H(s) = s + 4, with negative feedbac…

Q3
50M solve Control systems, microprocessors and power cables

(a) Write the state and output equations for the system shown in the figure. Choose state variables x₁ and x₂ as shown in the figure. Check the controllability and observability o…

Q4
50M solve Error control coding, transmission lines and microprocessor interrupts

(a) Consider a systematic linear block code with binary elements whose parity check equations are p₁ = m₁ + m₂ + m₃ p₂ = m₂ + m₃ + m₄ p₃ = m₁ + m₃ + m₄ p₄ = m₁ + m₂ + m₄ where mᵢ…

Q5
50M Compulsory calculate Control systems, instrumentation, power systems, communication, protection

(a) The figure shows a compensator network, where R₁ = 3 MΩ, R₂ = 1 MΩ, C = 1 μF. Vᵢ(t) and Vₒ(t) are the input voltage and output voltage respectively. [Figure: R₁ in series with…

Q6
50M solve Economic load dispatch, power system analysis, microprocessor, control systems

(a) (i) A power system has two generators with the following cost curves : Generator 1 : C₁(P_g1) = 0.008 P_g1² + 8 P_g1 + 380 (thousand rupees/hour) Generator 2 : C₂(P_g2) = 0.00…

Q7
50M design Information theory, relay characteristics, power distribution

(a) A discrete memoryless source generates three independent message symbols m_1, m_2 and m_3 with probabilities 0·9, 0·08 and 0·02 respectively. (i) Design a binary variable leng…

Q8
50M solve Control systems, measurement, power system fault analysis

(a) The figure shows a unity feedback system with G(s) = 2/[s(s+1)(s+2)(s+3)]. (i) Sketch the approximate polar plot of G(s). (ii) Determine the closed-loop stability of the syste…

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