BITS Pilani, Hyderabad Campus

Department of Electrical and Electronics Engineering

Course: Power Systems Course number: EEE F312

Student’s Name: ID no.:

Note: MCQ carries 3 marks each, and negative mark of -1 for every wrong answer.

ANSWER TABLE: Fill in Capital Letters using Pen only

Q.1 Q.2 Q.3 Q.4 Q.5 Q.6 Q.7 Q.8 Q.9 Q.10

PART-A (MCQ)
Q.1) A transformer rated 200 MVA, 345 Y/ 20.5 ∆ kV connected at the receiving end of a transmission
line feeds a balanced load rated 180 MVA, 22.5 kV, 0.8 power factor. The complex impedance of the
load in per-unit, if the base in the transmission line is 100 MVA, 345 kV is

A. 0.5752 + j 0.3612 B. 0.5552 + j 0.3813 C. 0.5352 + j 0.4013 D. 0.5052 + j 0.4212

Q.2) A 3-φ, 50 Hz, 400 kV, 300 km long transmission line has inductance 1 mH/km/phase and the
capacitance 0.01 µF/km/phase. The line is under open-circuit condition at the receiving end and
energized with 400 kV at the sending end. The receiving end line voltage will be
A. 418.59 kV B. 444.55 kV C. 454.59 kV D. 480.55 kV

Q.3) The figure shows a transposed 3-φ, 50 Hz, 200 km line employing two bundle conductors per phase.
The total reactance of the line is

50 cm 50 cm 50 cm

5 cm 5 cm 5 cm
10 m 10 m

A. 58.23 Ω B. 60.93 Ω C. 65.32 Ω D. 70.54 Ω

Q.4) A 1-φ, 33 kV, 50 Hz, 5 km line is spaced 1.5 m apart and the diameter of the conductors is 10 mm.
The capacitance between the line considering the earth effect for ground clearance of 5 m is
A. 0.0444 µF B. 0.0344 µF C. 0.0244 µF D. 0.0144 µF
Power System Midsem Examination Page 2 of 2

Q.5) A 33-kV, 3-φ transmission line has per-phase resistance and reactance of the line is 20 Ω and 50 Ω,
respectively supplying a load of 1000 kW at a lagging power factor of 0.8. If 33 kV is to be maintained
at the receiving end, the required sending end voltage is
A. 34.75 kV B. 38.55 kV C. 40.25 kV D. 42.15 kV

Q.6) Using the data of Q.5, the efficiency of the line is

Q.7) A 3-φ, 400-kV, 50-Hz, 300 km transmission line has a series inductive reactance of 0.30 Ω/km and a
shunt admittance of 3.75 µS/km. The propagation constant per km of the line is
A. j0.0011 B. j0.0022 C. j0.0033 D. j0.0044

Q.8) Using the data of Q.7, the Surge Impedance Loading (SIL) of the line is
A. 565.68 MW B. 555.68 MW C. 465.68 MW D. 455.68 MW

Q.9) A 75 Km, 400 kV transmission line has resistance of 0.017 Ω/km and inductive reactance of 0.27 Ω/km,
respectively, is used to transmit 1800 MW to a load with a power factor of 0.9 lagging. Choosing a base
of 2000 MVA and 400 kV, the per-unit impedance of the line is
A. 0.052 + j 0.806 B. 0.032 + j 0.506 C. 0.072 + j 0.906 D. 0.042 + j 0.606

Q.10) Using the data of Q.9, the sending end voltage of the line is
A. 530 kV B. 540 kV C. 550 kV D. 560 kV

PART-B (Subjective)
1. A 66 kV, 50 Hz, 60 km line delivers a load of 25 MW at 0.8 lagging power factor. If the line has a
series resistance and inductance of 0.08 Ω/km and 1.25 mH/km, respectively. Compute (a) sending
end voltage and current, (b) voltage regulation, and (c) transmission efficiency. 20-marks
2. A 400 km long transmission line has resistance and series inductive reactance of 0.0251 Ω/km and
0.5541 Ω/km, respectively. The shunt capacitive susceptance of the line is 7.4722 µS/km to neutral.
Determine the ABCD parameters of the line. If a load of 1500 MVA at 700 kV with 0.95 pf lag is
applied then determine the efficiency of the line? 20-marks
3. Draw an impedance diagram for the electric power system shown in Fig.1 showing all impedances in
per unit on a 100-MVA base. Choose 20 kV as the voltage base for generator. The three-phase power
and line-line ratings are given below 20-marks
G1 : 90 MVA 20 kV X = 9%
T1 : 80 MVA 20/200 kV X = 16%
T2 : 80 MVA 200/20 kV X = 20%
G2 : 90 MVA 18 kV X = 9%
Line : 200 kV X = 120 Ω
Load : 200 kV S = 48 M W + j64 M V Ar

T1 T2
1 2
Line
G1 G2

Load

Figure 1: A single-line diagram of a power system

Student’s name & Id: End of exam F