Recent questions and answers in Electric Power Transmission

1 answer 383 views

The main consideration for operating transmission line at high voltage is (a) to increase efficiency only. (b) to reduce power loss only. (c) to increase power transmission capability only. (d) All of the above

answered Jul 8 in Electric Power Transmission
2 answers 360 views
2 answers 53 views

A long transmission line has considerable ……………….. effect. A) series capacitance B) shunt capacitance C) series inductance D) shunt inductance

answered Aug 12, 2018 in Electric Power Transmission
1 answer 46 views

A single-line-to-ground fault on a overhead transmission line creates (A) voltage sag (B) voltage swell (C) over voltage (D) voltage flicker 

answered Aug 11, 2018 in Electric Power Transmission
1 answer 30 views

For a transmission line open circuit and short circuit impedances are 20 Ω and 5 Ω. Then characteristic impedance is: (1) 100 Ω (2) 50 Ω (3) 25 Ω (4) 10 Ω

answered May 29, 2018 in Electric Power Transmission
1 answer 191 views

A 10 km long line has a characteristic impedance of 400 ohms. If line length is 100 km, the characteristic impedance is: (1) 4000 Ω (2) 400 Ω (3) 40 Ω (4) 4 Ω

answered May 28, 2018 in Electric Power Transmission
0 answers 59 views

A cable has inductance of 0.22 mH per kilometer and capacitance of 0.202 µF per kilometer. The surge impedance of the cable is (a) 50 Ω (b) 42 Ω (c) 33 Ω (d) 28 Ω

asked May 26, 2018 in Electric Power Transmission
0 answers 34 views

In an AC transmission line difference in phase of voltage at two ends of the line is due to (a) System voltage (b) Insulators (c) Resistance of line (d) Reactance of line

asked May 26, 2018 in Electric Power Transmission
0 answers 43 views

If 5000 kW power is transmitted at 220 kV in place of 11 kV, reduction in the value of electric current will be (a) 90% (b) 95% (c) 5% (d) 10% 

asked May 26, 2018 in Electric Power Transmission
0 answers 23 views

In long AC transmission lines, the receiving end voltage becomes greater than sending end voltage at light load or no load operation. This is due to (a) Ferranti effect (b) Skin effect (c) Proximity effect (d) Corona effect 

asked May 26, 2018 in Electric Power Transmission
0 answers 100 views

For extra high voltage ac transmission lines, conductors used are (a) All aluminium (b) All steel (c) AAAC (d) ACSR

asked May 26, 2018 in Electric Power Transmission
0 answers 31 views

Which of the following relations is true for long transmission line ? (a) VS = AVR – BIR (b) VS = BVR + AIR (c) VS = AVR + BIR (d) VS = BVR – AIR

asked May 26, 2018 in Electric Power Transmission
0 answers 25 views

Which of the following is used for power factor improvement in transmission line ? (a) Three phase induction (b) An overexcited three phase synchronous motor running on no load (c) Three phase AC series motor (d) Choke

asked May 26, 2018 in Electric Power Transmission
0 answers 47 views

The connected load of a consumer is 2 kW and his maximum demand is 1.5 kW. The load factor of the consumer is (a) 0.375 (b) 0.75 (c) 1.33 (d) None of these  

asked May 26, 2018 in Electric Power Transmission
0 answers 21 views

If diameter of each conductor of a transmission line is ‘d’, then the diameter of n-layer stranded conductor will be (a) (2n – 1) d (b) (2n + 1) d (c) (3n – 1) d (d) (3n + 1) d 

asked May 26, 2018 in Electric Power Transmission
0 answers 16 views

The bundled conductor in EHV transmission line system provides (a) increased inductance (b) reduced capacitance (c) increased capacitance (d) increased voltage gradient

asked May 26, 2018 in Electric Power Transmission
0 answers 18 views

The power loss in a transmission line depends on (a) current in the line. (b) resistance of the line. (c) length of the line. (d) All of the above 

asked May 26, 2018 in Electric Power Transmission
0 answers 92 views

The presence of earth in case of overhead transmission line (a) increases capacitance (b) increases inductance (c) decreases capacitance (d) decreases inductance

asked May 26, 2018 in Electric Power Transmission
0 answers 40 views

Effect of increase in temperature in an overhead transmission line is (a) to increase stress and length both (b) to decrease stress and length both (c) to decrease stress and increase length (d) None of the above 

asked May 26, 2018 in Electric Power Transmission
0 answers 20 views

A transmission line to be reciprocal, the condition is (a) A = D (b) AC – BD = 1 (c) AD – BC = 1 (d) AB – CD = 1  

asked May 25, 2018 in Electric Power Transmission
0 answers 9 views

Shielding angle of an EHV line is about (a) 20° (b) 50° (c) 70° (d) 90°

asked May 25, 2018 in Electric Power Transmission
0 answers 22 views

An overhead transmission line has a span of 260 m. The weight of the conductor is 0.68 kg/m. The maximum allowable tension in the line is 1550 kg. Maximum sag of the line should be (a) 5.8 m (b) 4.6 m (c) 2.7 m (d) 3.7 m 

asked May 25, 2018 in Electric Power Transmission
1 answer 12 views

The input impedance of a short circuited loss less transmission line of characteristic impedance 50 Ohm is

answered May 23, 2018 in Electric Power Transmission
1 answer 20 views

Corona loss is less when the shape of conductor is:

answered May 22, 2018 in Electric Power Transmission
1 answer 20 views

What type of insulator will be used if the direction of the transmission line is to be changed?

answered May 22, 2018 in Electric Power Transmission
1 answer 20 views

Why are shunt reactors connected at the receiving end of long transmission line system: (1) To increase the terminal voltage (2) To compensate voltage rise caused by capacitive charging at light load (3) To improve power factor (4) None of these

answered May 22, 2018 in Electric Power Transmission
1 answer 26 views

In case of a ‘High Voltage DC’ transmission, how many minimum conductors are required?

answered May 22, 2018 in Electric Power Transmission
1 answer 26 views

Earth wire on EHV overhead transmission line is provided to protect the line against:

answered May 22, 2018 in Electric Power Transmission
1 answer 14 views

Consider the following statements: Over head transmission lines are provided with earth wires: 1 . To protect the transmission line from direct lightning strike 2. To protect the transmission line insulation from the indirect lightning strike 3. To balance the line currents 4. To provide path for neutral current Which of these statement/s is/are correct? (1) 1 and 3 (2) 1 and 4 (3) 1 only (4) 2 on|y

answered May 22, 2018 in Electric Power Transmission
1 answer 26 views

To increase power transfer capability of a long transmission line, we should:  (1) Increase line resistance (2) Increase transmission voltage (3) Decrease line reactance (4) Both (2) & (3)

answered May 22, 2018 in Electric Power Transmission
1 answer 11 views

Transmission of power by a.c. cables is impossible beyond   (a) 500 km (b) 300 km (c) 250 km (d) 45 km 

answered May 13, 2018 in Electric Power Transmission
1 answer 41 views

The inductance of single phase two wire power transmission line per km gets doubled when the  (a) Distance between wires is doubled  (b) Distance between the wires is increased four fold  (c) Distance between the wires is increased as square of the original distance  (d) Radius of the wire is doubled

answered May 13, 2018 in Electric Power Transmission
1 answer 80 views

Galloping in transmission line conductors arises generally due to - (A) asymmetrical layer of ice formation (B) vortex phenomenon in light winds (C) heavy weight of line conductors (D) adoption of horizontal conductor

answered May 13, 2018 in Electric Power Transmission
1 answer 27 views

The inductance of a power transmission line increases with (A) decrease in line length. (B) increase in conductor diameter. (C) increase in spacing between phase conductors. (D) increase in load current carried by conductors.

answered May 13, 2018 in Electric Power Transmission
1 answer 391 views

In which of the following transmission lines, the value of the Shunt admittance should be approximated to zero ? (A) A 66 kV 35 km long line (B) A 132 kV 200 km long line (C) A 220 kV 300 km long line (D) A 400 kV 500 km long line

answered May 8, 2018 in Electric Power Transmission
1 answer 15 views

The electric breakdown strength of insulating materials depends on  (A) Nature of applied voltage (B) lmperfection of dielectric material (C) Pressure, temperature and humidity (D) All or these

answered May 8, 2018 in Electric Power Transmission
1 answer 53 views

A 40 kVA transformer has a core loss of 400 W and a full load copper loss of 800 W. The proportion of full load at maximum efficiency is

answered May 8, 2018 in Electric Power Transmission
1 answer 35 views

The number of insulator discs (each rated 11 kV) required in a suspension type insulator string of 220 kV line is 

answered May 8, 2018 in Electric Power Transmission
1 answer 29 views

A 3 layer, total diameter of an ACSR conductor is 5 cm. Find the diameter of each strand?

answered May 8, 2018 in Electric Power Transmission
1 answer 61 views

If the insulation resistance of a cable of length 10 km is 1 mega ohm, its insulation resistance for 50 km length will be

answered May 8, 2018 in Electric Power Transmission
1 answer 30 views
1 answer 54 views

The function of steel wire in ACSR conductors is (A) To take care of surges. (B) To reduce corona. (C) To reduce inductance. (D) To provide additional mechanical strength

answered May 8, 2018 in Electric Power Transmission
1 answer 115 views

In a transmission line if booster transformers are to be used, preferred location will be  (A) At the receiving end (B) At the sending end (C) At the intermediate point (D) Anywhere in the line 

answered May 8, 2018 in Electric Power Transmission
1 answer 24 views

For 11kV line the inductance per km per phase will be of the order of:  (A) 1 H (B) 0.1 H (C) 1 mH (D) 0.1 mH

answered May 8, 2018 in Electric Power Transmission
1 answer 18 views

For 11 kV line the capacitance per km per phase will be of the order of:  (A) 1 Farad (B) 0.1 Farad (C) 0.01 Farad (D) 0.01 microF

answered May 8, 2018 in Electric Power Transmission
1 answer 70 views

In case the height of transmission tower is increased, which of the following parameter is likely to change?  (A) Resistance (B) Inductance (C) Capacitance (D) None of the above

answered May 8, 2018 in Electric Power Transmission
1 answer 51 views

If 3000 kW power is to be transmitted over a distance of 30 km, the desirable transmission voltage will be.  (A) 11 kV (B) 33 kV (C) 66 kV (D) 132 kV

answered May 8, 2018 in Electric Power Transmission
1 answer 148 views

A 50 Hz, 4 pole turboalternator rated at 20 MVA. 13.2 KV has an inertia constant H = 4 KW sec/KVA. The K.E. stored in the rotor at synchronous speed is

answered May 3, 2018 in Electric Power Transmission
1 answer 92 views

A transmission line has 1 P.0 impedance on a base of 11 KV, 100 MVA. On a base of 55 KV. it will have a P.0 impedance of

answered May 3, 2018 in Electric Power Transmission
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