Back to Sections

Type:ALLMCQNATMSQ

Generation, Transmission & Load Flow(22)Fault Analysis, Protection & Stability(12)

Generation, Transmission & Load Flow

22 Questions

GATE→2026→Power Systems→Generation, Transmission & Load Flow

Q1

MCQ[1 Mark]

In a power system with N buses (P generator buses, Q load buses), what is the size of the Jacobian matrix in the Newton-Raphson method?

(A)

2N x 2N

(B)

(2N - 1 - P) x (2N - 1 - P)

(C)

(2N - Q) x (2N - Q)

(D)

(P + Q) x (P + Q)

Explanation

GATE→2026→Power Systems→Generation, Transmission & Load Flow

Q2

MCQ[2 Marks]

For a transformer with voltage ratio V_p/V_s = 0.866 + j0.5 and leakage admittance y_t referred to secondary, what is the Y-bus matrix?

(A)

[I_p; I_s] = [ y_t/(0.866+j0.5), -y_t/(0.866+j0.5); -y_t/(0.866+j0.5), y_t/(0.866+j0.5) ] [V_p; V_s]

(B)

[I_p; I_s] = [ y_t, -y_t; -y_t, y_t ] [V_p; V_s]

(C)

[I_p; I_s] = [ y_t, -y_t/(0.866+j0.5); -y_t/(0.866+j0.5), y_t ] [V_p; V_s]

(D)

[I_p; I_s] = [ y_t, -y_t/(0.866-j0.5); -y_t/(0.866+j0.5), y_t ] [V_p; V_s]

Explanation

GATE→2026→Power Systems→Generation, Transmission & Load Flow

Q3

MSQ[2 Marks]

For the balanced transmission line under Case-1 (Z = 0.75<0°) and Case-2 (Z = 0.75<90°), which statements regarding power losses are correct?

(A)

Real power loss in Case-1 is more than that in Case-2

(B)

Real power loss in Case-2 is more than that in Case-1

(C)

Reactive power loss in Case-1 is more than that in Case-2

(D)

Reactive power loss in Case-2 is more than that in Case-1

Explanation

GATE→2026→Power Systems→Generation, Transmission & Load Flow

Q4

NAT[2 Marks]

For economic load dispatch with given cost functions and loss formula, find the real power loss at optimal generation (Lambda = 70.25).

Explanation

GATE→2025→Power Systems→Generation, Transmission & Load Flow

Q5

MCQ[1 Mark]

During power failure, a household UPS supplying power to lights and fans is represented in NR load-flow as a

(A)

Slack bus

(B)

PV bus

(C)

PQ bus

(D)

PQV bus

Explanation

GATE→2025→Power Systems→Generation, Transmission & Load Flow

Q6

NAT[1 Mark]

For a distribution feeder with R/X = 5, find the load power factor at which maximum voltage drop occurs.

Explanation

GATE→2025→Power Systems→Generation, Transmission & Load Flow

Q7

NAT[2 Marks]

A 3-phase 4 kV induction motor draws 390 kVA at 0.77 pf lag. Shunt capacitors correct pf to 0.85 pf lag. Find capacitor bank line current in A.

Explanation

GATE→2025→Power Systems→Generation, Transmission & Load Flow

Q8

NAT[2 Marks]

Given incremental cost data for two generating units, find total plant output at incremental cost of 11,800 Rs/MWh without exceeding unit capacities.

Explanation

GATE→2024→Power Systems→Generation, Transmission & Load Flow

Q9

MCQ[1 Mark]

For the 4-bus network with branch impedances 4z, z, 2z, 4z, which branch should be opened for minimum loss?

(A)

b_1

(B)

b_2

(C)

b_3

(D)

b_4

Explanation

GATE→2024→Power Systems→Generation, Transmission & Load Flow

Q10

NAT[1 Mark]

Using the incremental cost curves for Gen A and Gen B, find the common load in MW when incremental cost is Rs. 7400/MWh.

Explanation

GATE→2024→Power Systems→Generation, Transmission & Load Flow

Q11

MCQ[2 Marks]

A synchronous generator supplies an inductive load (pf = sqrt(3)/2) through a line (X = 5 ohm). With X_s = 30 ohm at rated voltage and current, find the generator terminal power factor.

(A)

0.63 lagging.

(B)

0.87 lagging.

(C)

0.63 leading.

(D)

0.87 leading.

Explanation

GATE→2024→Power Systems→Generation, Transmission & Load Flow

Q12

MCQ[2 Marks]

For the 3-bus lossless network with given reactances and P_1 = m P_2, if power flow from bus 1 to bus 2 is 0 pu, which condition holds?

(A)

gamma = m beta

(B)

beta = m gamma

(C)

alpha = m gamma

(D)

alpha = m beta

Explanation

GATE→2024→Power Systems→Generation, Transmission & Load Flow

Q13

MSQ[2 Marks]

Which options are correct regarding Automatic Generation Control (AGC) and Automatic Voltage Regulator (AVR)?

(A)

AGC response has a local effect on frequency while AVR response has a global effect on voltage.

(B)

AGC response has a global effect on frequency while AVR response has a local effect on voltage.

(C)

AGC regulates the field current of the synchronous generator while AVR regulates the generator's mechanical power input.

(D)

AGC regulates the generator's mechanical power input while AVR regulates the field current of the synchronous generator.

Explanation

GATE→2023→Power Systems→Generation, Transmission & Load Flow

Q14

MCQ[1 Mark]

When parameter 'a' in the fuel cost function of unit 1 increases by 10% under economic dispatch, what happens to P_G1 and total cost F?

(A)

P_G1 will decrease and F will increase

(B)

Both P_G1 and F will increase

(C)

P_G1 will increase and F will decrease

(D)

Both P_G1 and F will decrease

Explanation

GATE→2023→Power Systems→Generation, Transmission & Load Flow

Q15

MSQ[1 Mark]

Given the Y_bus matrix of a 3-bus power system with no shunt reactors, which statements can NOT be true regarding line charging and shunt capacitors?

(A)

Line charging capacitor of finite value is present in all three lines

(B)

Line charging capacitor of finite value is present in line 2-3 only

(C)

Line charging capacitor of finite value is present in line 2-3 only and shunt capacitor of finite value is present in bus 1 only

(D)

Line charging capacitor of finite value is present in line 2-3 only and shunt capacitor of finite value is present in bus 3 only

Explanation

GATE→2023→Power Systems→Generation, Transmission & Load Flow

Q16

NAT[1 Mark]

For a 400 km, 275 kV transmission line represented by nominal-pi model, find the phase angle difference delta for maximum active power delivery in degrees.

Explanation

GATE→2023→Power Systems→Generation, Transmission & Load Flow

Q17

MCQ[2 Marks]

For the 3-bus power system with specified generation, infinite bus, and controlled current source, categorize buses 1, 2, and 3 for load flow analysis.

(A)

Bus 1: Slack bus, Bus 2: PV bus, Bus 3: PQ bus

(B)

Bus 1: PV bus, Bus 2: Slack bus, Bus 3: PV bus

(C)

Bus 1: PQ bus, Bus 2: PQ bus, Bus 3: Slack bus

(D)

Bus 1: PV bus, Bus 2: P-Q bus, Bus 3: Slack bus

Explanation

GATE→2023→Power Systems→Generation, Transmission & Load Flow

Q18

NAT[2 Marks]

For a balanced delta load supplied through line inductance L = 31.83 mH per phase from a 415 V source, find the magnitude of terminal voltage V_AB in volts.

Explanation

GATE→2022→Power Systems→Generation, Transmission & Load Flow

Q19

MCQ[1 Mark]

Find the geometric mean radius (GMR) of a conductor having four equal strands of radius r arranged in a square bundle.

(A)

4r

(B)

1.414 r

(C)

2r

(D)

1.723 r

Explanation

GATE→2022→Power Systems→Generation, Transmission & Load Flow

Q20

NAT[1 Mark]

If 5% of the supplied power reaches the output of a cable, what is the power loss in decibels?

Explanation

GATE→2022→Power Systems→Generation, Transmission & Load Flow

Q21

MCQ[2 Marks]

For two thermal power plants with given cost functions and incremental cost lambda = 8 Rs/MWh meeting 550 MW demand, find optimal P1 and P2.

(A)

200, 350

(B)

250, 300

(C)

325, 225

(D)

350, 200

Explanation

GATE→2022→Power Systems→Generation, Transmission & Load Flow

Q22

NAT[2 Marks]

Two generating units (250 MW, R=6% and 400 MW, R=6.4%) share a 500 MW load in parallel. Find the load shared by the 250 MW unit in MW.

Explanation

Fault Analysis, Protection & Stability

12 Questions

GATE→2026→Power Systems→Fault Analysis, Protection & Stability

Q23

MCQ[1 Mark]

When balanced three-phase voltage phasors undergo a common phase shift delta_theta (Case-2), what happens to their zero sequence components?

(A)

The zero sequence components in Case-1 and Case-2 have the same phase angle and magnitude

(B)

The magnitude of the zero sequence component in Case-1 is greater than that in Case-2

(C)

The magnitude of the zero sequence component in Case-2 is greater than that in Case-1

(D)

The zero sequence components in Case-1 and Case-2 have the same magnitude but different phase angles

Explanation

GATE→2026→Power Systems→Fault Analysis, Protection & Stability

Q24

MCQ[2 Marks]

Given Main CT 300:5 and auxiliary transformer YnA 2:1, find I_AR.

(A)

0 A

(B)

0.653<17.556° A

(C)

537.240<4.105° A

(D)

8.954<4.105° A

Explanation

GATE→2026→Power Systems→Fault Analysis, Protection & Stability

Q25

MCQ[2 Marks]

A reactance relay has characteristic X <= 1 ohm. What is its operating characteristic in the G-B admittance plane?

(A)

G^2 + (B + 0.5)^2 >= 1/4

(B)

B >= 1

(C)

(G - 1)^2 + B^2 <= 1/2

(D)

G^2 + (B - 1)^2 >= 1/2

Explanation

GATE→2025→Power Systems→Fault Analysis, Protection & Stability

Q26

NAT[1 Mark]

Given Z_bus for a 3-bus system, find the voltage at bus 1 during a symmetrical fault at bus 2 with fault impedance j0.007 pu.

Explanation

GATE→2025→Power Systems→Fault Analysis, Protection & Stability

Q27

MCQ[2 Marks]

For a temporary fault and clearance in a single-machine infinite bus system, which P-delta curve diagram best indicates rotor accelerating and decelerating areas?

(A)

Fig. (i)

(B)

Fig. (ii)

(C)

Fig. (iii)

(D)

Fig. (iv)

Explanation

GATE→2024→Power Systems→Fault Analysis, Protection & Stability

Q28

MSQ[2 Marks]

For Clarke's transformation expressing phase voltages in terms of alpha-beta components, which matrices S are valid?

(A)

[1 1; 1 -1]

(B)

[1 1; 1 1]

(C)

[1 1; 1 0]

(D)

[-1 1; 1 1]

Explanation

GATE→2024→Power Systems→Fault Analysis, Protection & Stability

Q29

NAT[2 Marks]

For the single-machine infinite bus system with critical clearing angle pi/2 and given pre/during/post-fault power curves, find the accelerating area in terms of P_max.

Explanation

GATE→2023→Power Systems→Fault Analysis, Protection & Stability

Q30

MCQ[1 Mark]

For the 3-bus power system protection scheme, what is the necessary condition regarding directional overcurrent relays?

(A)

R_3 and R_4 are directional overcurrent relays blocking faults towards bus 2

(B)

R_3 and R_4 are directional overcurrent relays blocking faults towards bus 2 and R_7 is directional overcurrent relay blocking faults towards bus 3

(C)

R_3 and R_4 are directional overcurrent relays blocking faults towards Line 1 and Line 2, respectively...

(D)

R_3 and R_4 are directional overcurrent relays blocking faults towards Line 1 and Line 2, respectively.

Explanation

GATE→2023→Power Systems→Fault Analysis, Protection & Stability

Q31

NAT[2 Marks]

For a bolted line-to-line fault between phases b and c at bus 1 in the 2-bus power system, find the magnitude of the fault current in p.u.

Explanation

GATE→2022→Power Systems→Fault Analysis, Protection & Stability

Q32

MCQ[1 Mark]

Which relay is most commonly used to protect an alternator against loss of excitation?

(A)

offset Mho relay.

(B)

over current relay.

(C)

differential relay.

(D)

Buchholz relay.

Explanation

GATE→2022→Power Systems→Fault Analysis, Protection & Stability

Q33

MCQ[1 Mark]

What are typical valid positive, negative, and zero sequence impedances (in p.u.) for a 220 kV fully transposed 3-phase transmission line?

(A)

1.1, 0.15 and 0.08

(B)

0.15, 0.15 and 0.35

(C)

0.2, 0.2 and 0.2

(D)

0.1, 0.3 and 0.1

Explanation

GATE→2022→Power Systems→Fault Analysis, Protection & Stability

Q34

NAT[2 Marks]

A 20 MVA, 50 Hz alternator has H = 15 MJ/MVA, P_m = 15 MW, P_e = 10 MW. Find angular acceleration in mechanical degrees/s^2.

Explanation