# An overhead transmission line has a span of 240m between level ...

An overhead transmission line has a span of 240m between level supports. What is the maximum sag if the conductor weight 727 kg/km and has a breaking strength of 6880 kg? Allow the factor of safety of 2. Neglecting wind and ice loading.

An overhead transmission line has a span of 240m between level supports. 1.52 m is the maximum sag if the conductor weight 727 kg/km and has a breaking strength of 6880 kg? Allow the factor of safety of 2. Neglecting wind and ice loading.

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Description : 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

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Description : Two trains 240m and 170m in length are running towards each other on parallel tracks. One train has a speed of 51kmph and the other has a speed of 45kmph. In what time after the meet first will they be clear of each other? a) 6.714s b) 12.2 s c) 15.375s d) 16s

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Description : A 240m train crosses a standing object in 6 seconds. Find the time taken by the train to cross a long pole of length 162.5 m. A) 25 B) 45 C) 10 D) 15

Last Answer : ANSWER:C Explanation: Length of the train = 240 m Time taken to cross an object = 6 seconds Speed of the train = Length of the train / Time taken to cross an object  = 240/6 m/s  = 40 m/s  Length of ...  = (240 + 162.5)/40  = 402.5/40  = 10.06 seconds  Hence the answer is 10 seconds.

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

Description : 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

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

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Last Answer : Surge impedance of overhead transmission line is normally in the order of 300 - 500 ohms

Description : What is the sag for a span of 400m, if the ultimate tensile strength of conductor is 6000 kgf, and the weight of conductor is 550 kgf/km? Factor of safety is 2.

Last Answer : 3.6 m is the sag for a span of 400m, if the ultimate tensile strength of conductor is 6000 kgf, and the weight of conductor is 550 kgf/km? Factor of safety is 2.

Description : A 20-MVA, 6.6-kV, 3-phase alternator is connected to a 3-phase transmission line. The per unit positive-sequence, negative-sequence and zero-sequence impedances of the alternator are j0.1, j0.1 and j0.04 respectively. The neutral of ... the fault is  (A) 513.8 V (B) 889.9 V (C) 1112.0 V (D) 642.2 V

Last Answer : A 20-MVA, 6.6-kV, 3-phase alternator is connected to a 3-phase transmission line. The per unit positive-sequence, negative-sequence and zero-sequence impedances of the alternator are j0.1, ... line. The voltage of the alternator neutral with respect to ground during the fault is 642.2 V

Description : Choose two appropriate auxiliary components of a HVDC transmission system from the following P. D.C line inductor Q. A.C line inductor R. Reactive power sources S. Distance relays on D.C line T. Series capacitance on A.C. line  (A) P and Q (B) P and R (C) Q and S (D) S and T

Last Answer : Choose two appropriate auxiliary components of a HVDC transmission system from the following P. D.C line inductor Q. A.C line inductor R. Reactive power sources S. Distance relays on D.C line T. Series capacitance on A.C. line  (A) P and Q (B) P and R (C) Q and S (D) S and T

Description : A 800 kV transmission line is having per phase line inductance of 1.1 mH/km and per phase line capacitance of 11.68 nF/km. Ignoring the length of the line, its ideal power transfer capability in MW is (A) 1204 MW (B) 1504 MW (C) 2085 MW (D) 2606 MW

Last Answer : A 800 kV transmission line is having per phase line inductance of 1.1 mH/km and per phase line capacitance of 11.68 nF/km. Ignoring the length of the line, its ideal power transfer capability in MW is 2085 MW

Description : The transmission line distance protection relay having the property of being inherently directional is (A) impedance relay (B) MHO relay (C) OHM relay (D) reactance relay

Last Answer : The transmission line distance protection relay having the property of being inherently directional is MHO relay

Description : An 800 kV transmission line has a maximum power transfer capacity of P. If it is operated at 400 kV with the series reactance unchanged, the new maximum power transfer capacity is approximately (A) P (B) 2P (C) P / 2 (D) P / 4

Last Answer : An 800 kV transmission line has a maximum power transfer capacity of P. If it is operated at 400 kV with the series reactance unchanged, the new maximum power transfer capacity is approximately P / 4

Description : A generator is connected through a 20 MVA, 13.8/138 kV step down transformer, to a transmission line. At the receiving end of the line a load is supplied through a step down transformer of 10 MVA, 138/69 kV rating. A 0.72 ... load (in per unit) in generator will be (A) 36 (B) 1.44 (C) 0.72 (D) 0.18

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Description : An HVDC link consist of rectifier, inverter transmission line and other equipments. Which one of the following is true for this link ?  (A) The transmission line produces/ supplies ... ) Both the converters (rectifier and inverter) consume reactive power from the respective connected AC systems

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Description : A loss less transmission line having Surge Impedance Loading (SIL) of 2280 MW is provided with a uniformly distributed series capacitive compensation of 30%. Then, SIL of the compensated transmission line will be (A) 1835 MW (B) 2280 MW (C) 2725 MW (D) 3257 MW

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Description : For enhancing the power transmission in along EHV transmission line, the most preferred method is to connect a  (A) Series inductive compensator in the line (B) Shunt inductive compensator at the ... (C) Series capacitive compensator in the line (D) Shunt capacitive compensator at the sending end

Last Answer : For enhancing the power transmission in along EHV transmission line, the most preferred method is to connect a Series capacitive compensator in the line

Description : For a fixed value of complex power flow in a transmission line having a sending and voltage V, the real power loss will be proportional to  A) V B) v2 C) 1/V2 D)1/V

Last Answer : For a fixed value of complex power flow in a transmission line having a sending and voltage V, the real power loss will be proportional to 1/V2

Description : Which of the two generalized constants of a transmission line are equal?  (a) B & C (B) A & B (c) A & D (D) B & D

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Description : Series capacitive compensation in EHV transmission line is used to

Last Answer : To maintain voltage stability

Description : The sending end and receiving end voltages of a three-phase transmission line are 10 kV/ph and 9.5 kV/ph, respectively. If the resistance drop is 150 V/ph and receiving end power factor is 0.8, the sending end power factor is (A) 0.745 lagging (B) 0.775 lagging (C) 0.8 lagging (D) 0.85 lagging

Description : The transmission line feeding power on either side of the main transmission line is called?

Last Answer : The transmission line feeding power on either side of the main transmission line is called Secondary transmission.

Description : For a transmission line with negligible losses, the lagging reactive power (VAR) delivered at The receiving end, for a given receiving end voltage, is directly proportional to the?

Last Answer : For a transmission line with negligible losses, the lagging reactive power (VAR) delivered at The receiving end, for a given receiving end voltage, is directly proportional to the line voltage drop.

Last Answer : A lossless radial transmission line with surge impedance loading takes negative VAr at sending end and zero VAr at receiving end.

Description : The line conductor of a transmission line has an overall diameter of 19.53 mm, weight 0.844 kg/m and an ultimate breaking strength of 7950 kg. If the factor of safety is to be 2, when conductor ... .5 kg/m. What is the vertical sag, corresponding to this loading for a 300 m span level supports?

Last Answer : The line conductor of a transmission line has an overall diameter of 19.53 mm, weight 0.844 kg/m and an ultimate breaking strength of 7950 kg. If the factor of safety is to be 2, when conductor ... 5 kg/m. 5.22 m is the vertical sag, corresponding to this loading for a 300 m span level supports.

Description : A transmission line conductor at a river crossing is supported from two towers at height. of 30 m and 90m, above water level. The horizontal distance between the towers is 270m, if the tension in ... . What is the clearance between the conductor and the water at a point midway between the towers?

Last Answer : A transmission line conductor at a river crossing is supported from two towers at height. of 30 m and 90m, above water level. The horizontal distance between the towers is 270m, if the tension ...  54.94 m is the clearance between the conductor and the water at a point midway between the towers.

Description : If in a short transmission line, resistance and inductance are found to be equal and regulation appear. to be zero, then the load will?

Last Answer : If in a short transmission line, resistance and inductance are found to be equal and regulation appear. to be zero, then the load will be 0.707 lagging.

Description : A three phase overhead transmission line has its conductors horizontally spaced with spacing between adjacent conductors equal to 'd'. if now the conductors of the line are rearranged to form and the equilateral triangle of sides equal to 'd' then?

Last Answer : A three-phase overhead transmission line has its conductors horizontally spaced with spacing between adjacent conductors equal to 'd'. if now the conductors of the line are rearranged to form and an equilateral triangle of sides equal to 'd' then average capacitance and inductance will increase.

Description : For an existing ac transmission line, the string efficiency is 80%, if dc voltage is supplied for the same setup, the string efficiency will be?

Description :  A single-phase transmission line of impedance j 0.8 ohm supplies a resistive load of 500 A at 300 V. The sending end power factor is?

Last Answer :  A single-phase transmission line of impedance j 0.8 ohm supplies a resistive load of 500 A at 300 V. The sending end power factor is 0.6 lagging.

Description : A 100 km long transmission line is loaded at 110 kV.if the loss of line is 5 MW and the load is 150 MVA, the resistance of the line is?

Last Answer : P = I^2  *  R 5*10^6  = [(150*10^6) / (110*10^3)  *  R R = 2.7 ohm/phase

Description : A 100 km transmission line is designed for a nominal voltage of 132 kV and consists of one conductor per phase. The line reactance is 0.726 ohm/km. The static transmission capacity of the line, in MW, would be   (a) 240 (b) 132 (c) 416 (d) 720

Last Answer : A 100 km transmission line is designed for a nominal voltage of 132 kV and consists of one conductor per phase. The line reactance is 0.726 ohm/km. The static transmission capacity of the line, in MW, would be 240

Description : In a DC transmission line?

Last Answer : In a DC transmission line there are no effects due to inductive and capacitive reactances.

Description : Why Earth Wire is provided in the overhead transmission lines?

Last Answer : Earth wire is provided above the overhead transmission lines for protection against lightning strokes. The ground wire or earth wire protects the phase conductors or line conductors by attracting itself the ... traveling waves set in the lines by acting a short circuit secondary of the line current

Description : Most of the high voltage transmission lines in India are (a) underground (b) overhead (c) either of the above (d) none of the above

Description : The advantage of cables over overhead transmission lines is (a) easy maintenance (b) low cost (c) can be used in congested areas (d) can be used in high voltage circuits

Last Answer : (c) can be used in congested areas

Description : What is the material used for overhead transmission lines?

Description : Which of the following materials is used for overhead transmission lines ? (a) Steel cored aluminium (b) Galvanised steel (c) Cadmium copper (d) Any of the above

Last Answer : (d) Any of the above

Description : Most of the high voltage transmission lines in India are (a) underground (b) overhead (c) either of the above (d) none of the above

Description : Differentiate between overhead transmission and underground transmission.

Last Answer : Points Overhead line  Underground cable Capital cost  Less More Erecting cost  Less More Time require for completion of work Less More Flexibility More ... Space consumed Space consumed  No space consumed Appearance Not good  Very good

Description : Why are overhead transmission lines not insulated?

Last Answer : Insulators are useful to help separate electrical conductors when they come into physical contact. Overhead Transmission Lines Are Not Insulated: The overhead transmission line is carrying extreme high voltage and ... a whole lot of thick insulation to absorb the heat produced by such high voltage.

Description : Bundled conductors are mainly used in high voltage overhead transmission lines to (a) Reduce line loss (c) Reduce corona (b) Reduce harmonics (d) Increase strength

Last Answer : Bundled conductors are mainly used in high voltage overhead transmission lines to Reduce corona

Description : High Voltage DC (HVDC) transmission is mainly used for  (A) bulk power transmission over very long distances (C) inter-connecting two systems with same nominal frequency (C) eliminating reactive power requirement in the operation (D) minimizing harmonics at the converter stations

Last Answer : High Voltage DC (HVDC) transmission is mainly used for bulk power transmission over very long distances

Description : A cylinder rotor generator delivers 0.5 pu power in the steady-state to an infinite bus through a transmission line of reactance 0.5 pu. The generator no-load voltage is 1.5 pu and the infinite bus voltage is 1 pu. The ... fault at the generator terminal is  (A) 53.5 (B) 60.2 (C) 70.8 (D) 79.6

Last Answer : A cylinder rotor generator delivers 0.5 pu power in the steady-state to an infinite bus through a transmission line of reactance 0.5 pu. The generator no-load voltage is 1.5 pu and the ... clearing angle, in degrees, for a three-phase dead short circuit fault at the generator terminal is 79.6