1.Which of the following voltage regulation is considered to be the best
2. For a short line if the receiving-end voltage is = sending end voltage under loaded conditions
3. Charging current in transmission line
4. Transmission efficiency of a transmission line increases with the
5.The regulation of a line at full load 0.8 pf lagging is 12%. The regulation at full-load 0.8 pf leading can be
6. If in a short transmission line, resistance and inductive reactance are found to be equal and regulation appears to be zero, then the load will
7. Characteristic impedance of an overhead transmission line is usually in the range of
8.Surge impedance of a transformer is in the range of
9.The surge impedance of a 400 km long over head transmission line is 400 ohm For a 200 km length of the same line, the surge impedance will be
10.Multiple conductor lines have
11.The SIL of a single circuit 220 kV line is around
12. The diameter of each strand is d then the diameter of n-layer stranded conductor will be
13.By increasing the transmission voltage to double of its original value the same power can be dispatched keeping the line loss
14. The sag of the conductors of a transmission line is 2.5 m when the span is 250 m. Now if the height of supporting tower is increased by 25%, the sag will
15.The minimum clearance of high voltage lines from ground across streets is
16.The effect of wind pressure is more predominant on
17. Stringing chart is useful
18. Galloping in transmission line conductors arises due to
19. Hot template curves are plots of
20.Minimum horizontal clearance of a low voltage line from residential buildings must be
21.If a 132 kV line passes over residential building, the minimum vertical clearance from the roof of the building shall be
22.For a 400 kV line, the spacing between phase conductors is around is about
23.Wind loading in coastal regions is in the range of
24.Which of the following statements is correct?
25.The age of a transmission line is least affected owing to
26.The material (s) used in overhead transmission line are
27.“Expanded ACSR” are conductors composed of
28.Which of the following properties has got higher value for aluminium in comparison to that of copper?
29.Which type of copper wire is most suitable for power transmission?
30.Conductors used in transmission lines are stranded because of
31.For installation of switchgears and power transformers we usually use
32.Which of the following poles are bulky poles?
33. Maximum permissible span with wooden poles is
34.If variable part of annual cost on account of interest and depreciation on the capital out lay is equal to the annual cost of electrical energy wasted in the conductors., the total annual cost will be minimum and the corresponding size of conductor will be the most economical. This statement is known as
35.If 3 MW power is to be transmitted over a distance of 30 km, the desirable transmission voltage will be
36.The most economical voltage for transmitting given power over a known distance by overhead transmission lines is about
37.For a given amount of power to be transmitted over a certain distance with fixed power loss, the volume of copper required is
38. Transmitting power remaining the same, if the supply voltage of a dc 2-wire distributor is doubled saving in copper will be
39.For the same voltage drop, increasing the voltage of a distributor n-times
40.1-phase ac power
41.Series capacitors on transmission lines are of little use when
42.Capacitors are used in power system to
Explain:- Capacitors are used for many other things , but primarly It is used to maintain voltages at constant level between the Load end and Sending end . So despite It is mentioned that capacitors are used to Improve supply power factor , or Change load characteristics , the main focus is just to maintain Voltage regulation to the minimum .
43. Over-excited synchronous phase modifier
Explain:-.Synchronous phase modifier is basically a synchronous motor operating under no load and by adjusting the excitation it is used for controlling reactive power, so that power factor and voltage are controlled. If synchronous phase modifier is used under over excitation it works similar to a shunt capacitor delivering reactive power and absorbing leading reactive power. If synchronous phase modifier is used as under excitation it works similar to shunt reactor which absorbs lagging reactive power and delivers leading reactive power. This is used for ferranti effect.