POWER SYSTEMS 1

POWER  SYSTEMS

11. In thermal power plants, the pressure in the working fluid cycle is developed by
a) Condenser
b) Superheater
c) feed water
d) turbine
ans: d

12. Which material is used in controlling chain reaction in av nuclear reactor?
a) Thorium
b) Heavy water
c) Boron
d) Beryllium
ans: b

13. When a fixed amount of power is transmitted, the efficiency of transmission increases when
a) Voltage decreases, power factor remains constant
b) voltage increases, power factor increase
c) voltage decreases, power factor decreases
d) voltage constant, power factor decreases
ans: b

14. The surge impedance of 0.400km long OH line is 400 ohm for 200 km length of the same line, the surge impedance will be
a) 200 ohm
b) 800 ohm
c) 400 ohm
d) 100 ohm
ans: c

15. The insulation level of a 400 EHV OH transmission line is decided on the basis of
a) lightning voltage
b) switching overvoltage
c) corona inception voltage
d) radio and TV interference
ans: b

16. Bundled conductors are employed to improve the
a) appearance of the transmission line
b) mechanical stability of the line
c) decrease system stability
d) increase the short circuit current
ans: c

17. An OH line having a surge impedance of 400 ohms is connected in series with an underground cable having a surge impedance of 100 ohm. If a surge of 50 Kv travels from the line end towards the line cable junctions, the value of the transmitted voltage wave at the junction is
a) 30 kV
b) 20 kV
c) 80 kV
d) -30 Kv
ans: b

19. The load-carrying capability of a long AC transmission line is
a) always limited by the conductor size
b) limited by stability considerations
c) reduced at low ambient temperatures
d) decreased by the use of bundled conductors of single conductors.
ans: b

20. Corona losses are minimized when
a) corona size is reduced
b) smooth conductor is released
c) sharp points are provided in the hardware
d) current density in conductors is reduced
ans: b