# Power System 6

Electrical Engineering MCQ Question Papers: Campus Placement

Subject: Power System 6

Part 6: List for questions and answers of Power System

Q1. Surge impedance loading of a line is increased by which of the following compensation methods?

a) Shunt capacitor

b) Series capacitor

c) Shunt reactor

d) Both 1 and 2

Q2. A transmission line has surge impedance of 400 ohm, operating at Vs = Vr = 400 kV line is compensated with a shunt capacitance of 30%. Find the surge impedance loading with compensation?

a) 400 MW

b) 478 MW

c) 456 MW

d) 386 MW

Q3. A transmission line has surge impedance of 400 ohm, operating at Vs = Vr = 400 kV line is compensated with a shunt capacitance of 30%. The line is connected to a generator delivering 200 MW. Find the load angle with out and with compensation respectively?

a) 30 deg. and 45 deg.

b) 30 deg. and 26 deg.

c) 26 deg. and 30 deg.

d) 45 deg. and 26 deg.

Q4. If the load is short circuited, then reflection coefficient of voltage is

a) -1

b) 1

c) 0

d) -2

Q5. The Y bus matrix of a 100 bus interconnected system is 90% sparse. Then find the number of non zero elements in the Y bus matrix?

a) 9000

b) 90

c) 1000

d) 10

Q6. At slack bus, which one of the following combinations of variables is not specified?

a) P and V

b) P and Q

c) V and ohm

d) Q and V

Q7. Which of the following statements are true?

a) Bus admittance matrix is a sparse matrix

b) Bus impedance matrix is a full matrix

c) Both 1 and 2

d) Nether 1 nor 2

Q8. Which of the following statements is/are true? The elements of each row of a Y bus matrix for load flow studies in power system add up to zero

a) Always

b) If the shunt admittances at the buses are ignored

c) If the mutual couplings between transmission lines are absent

d) If both 2 and 3 are satisfied

Q9. In a Gauss Seidel load flow method, the number of iterations may be reduced if the correction in voltage at each bus is multiplied by

a) Gauss constant

b) Acceleration factor

c) Blocking factor

d) Lagrange multiplier

Q10. Pin insulators are used up to

a) 11 kV

b) 33 kV

c) 120 kV

d) Any voltage level

Q11. Find the number of insulator discs required in string insulator, if operating voltage is 220 kV and maximum voltage of each disc is 11 kV?

a) 20

b) 10

c) 13

d) 21

Q12. A cable has inductance of 0.22 mH per km and capacitance of 0.202 uF per km. The surge impedance of the cable is

a) 28 ohm

b) 33 ohm

c) 40 ohm

d) 52 ohm

Q13. Which of the following decides the insulation level of 400 kV, EHV line?

a) Lighting voltage

c) Skin effect

d) Switching over voltage

Q14. Which of the following insulator is practically used for railway crossings?

a) Pin insulator

b) String insulator

c) Strain insulator

d) All of the above

Q15. Which of the following statements is/are true? By increasing of temperature,

a) Sag increase

b) Tension decrease

c) Both 1 and 2

d) Nether 1 nor 2

Q16. Stock bridge dampers are used to

a) Increase the sag

b) Reduce the vibrations at the point of support

c) Reduce the tension

d) All of the above

Q17. String chart is drawn between

a) Temperature (T) on X- axis, sag(S) and tension (T) on Y-axis

b) T on Y-axis and S and T on on X-axis

c) Both 1 and 2

d) Nether 1 nor 2

Q18. A string insulator has 4 units. The voltage across the bottom most unit is 33.33% of total voltage. Its string efficiency is

a) 25%

b) 33.33%

c) 66.66%

d) 75%

Q19. A string type insulator has three units with self capacitance C and ground capacitance of 0.2 C having a string efficiency of

a) 78%

b) 80%

c) 82%

d) 76%

Q20. A guard ring is used in string type insulator having 3 units to improve string efficiency. Find the capacitance of metal link 2 if pin to earth capacitance of each unit is 1 F?

a) 1 F

b) 2 F

c) 4 F

d) 0.5 F

Part 6: List for questions and answers of Power System