# The per unit impedance ofa circuit element is 0.15. If the base kV and...

The per unit impedance ofa circuit element is 0.15. If the base kV and base MVA are halved, then the new value of the per unit impedance of the circuit element will be?

The per unit impedance ofa circuit element is 0.15. If the base kV and base MVA are halved, then the new value of the per unit impedance of the circuit element will be 0.30.

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Description : The per unit impedance of a circuit element is 0.30. If the base kV and base MVA are halved, then the new value of the per unit impedance of the circuit element will be:  (A) 0.3 (B) 0.6 (C) 0.003 (D) 0.006

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 : 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

Last Answer : 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 0.02 P.U

Description : A three-phase, 33 kV oil circuit breaker is rated 1200 A, 2000 MVA, 3 s. The symmetrical breaking current is  (A) 1200 A (B) 3600 A (C) 35 kA (D) 104.8 kA

Last Answer : A three-phase, 33 kV oil circuit breaker is rated 1200 A, 2000 MVA, 3 s. The symmetrical breaking current is 35 kA

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 impedance of a circuit is given by z=3+j4. Its conductance will be?

Last Answer : The impedance of a circuit is given by z=3+j4. Its conductance will be 3/25.

Description : A 50 Hz, 4-pole, 500 MVA, 22 kV turbo-generator is delivering rated megavolt amperes at 0.8 power factor. Suddenly a fault occurs reducing in electric power output by 40%. Neglect losses and assume constant power input to the ... the time of fault will be  (A) 1.528 (B) 1.018 (C) 0.848 (D) 0.509

Last Answer : A 50 Hz, 4-pole, 500 MVA, 22 kV turbo-generator is delivering rated megavolt amperes at 0.8 power factor. Suddenly a fault occurs reducing in electric power output by 40%. Neglect losses and assume ... the shaft. The accelerating torque in the generator in MNm at the time of fault will be 1.018

Description : A 4000 kVA, 11 kV/132 kV delta-star connected 3-phase transformer has reactance, x1 = 0.12 p.u. The actual value of x1 referred to the low voltage side is (A) 0.85 Ω (B) 3.63 Ω (C) 36.3 Ω (D) 252 Ω

Last Answer : A 4000 kVA, 11 kV/132 kV delta-star connected 3-phase transformer has reactance, x1 = 0.12 p.u. The actual value of x1 referred to the low voltage side is 3.63 Ω

Description : A 3-phase, 11 kv, 50 Hz, 200 kW load has a power factor of 0.8 lag. A delta connected 3-phase capacitor is used to improve the power factor to unity. The capacitance perphase of the capacitor in micro-farads is?

Last Answer : A 3-phase, 11 kv, 50 Hz, 200 kW load has a power factor of 0.8 lag. A delta connected 3-phase capacitor is used to improve the power factor to unity. The capacitance perphase of the capacitor in micro-farads is 1.316.

Description : For a given base voltage and base volt-amperes, the per unit impedance value is x. For the doubled base values of both voltage and volt-amperes, the per unit impedance will be (a) 2x (b) 0.25x (c) 0.5x (d) no change

Last Answer : Answer is 2x Base impedance =(base voltage) ²/base current

Description : The inertia constant of a 100 MVA, 11 kV water wheel generator is 4. The energy stored in the rotor at the synchronous speed is: A) 400 Mega Joule B) 400 Kilo Joule C) 25 Mega Joule D) 25 Kilo Joule

Last Answer : The inertia constant of a 100 MVA, 11 kV water wheel generator is 4. The energy stored in the rotor at the synchronous speed is: 400 Mega Joule

Description : A 3-phase 11 kV generator feeds power to a constant power unity power factor load of 100 MW through a 3-phase transmission line. The line-to line voltage at the terminals of the machine is maintained constant at 11 kV. The per ... 11 kV is  (A) 100 MVAR (B) 10.1 MVAR (C) -100 MVAR (D) -10.1 MVAR

Last Answer : A 3-phase 11 kV generator feeds power to a constant power unity power factor load of 100 MW through a 3-phase transmission line. The line-to line voltage at the terminals of the machine is maintained ... load to increase the line-to-line voltage at the load terminals to 11 kV is -10.1 MVAR

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

Last Answer : 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/ ... MVA and 69 kV in load circuit, the value of the load (in per unit) in generator will be 36

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 : A voltage of 1000 kV is applied to an overhead line with its receiving end open. If the surge impedance of the line is 500 ohm, then the total surge power in the line ill

Last Answer : A voltage of 1000 kV is applied to an overhead line with its receiving end open. If the surge impedance of the line is 500 ohm, then the total surge power in the line ill 2000 MW .

Description : The X:R ratio of 220 kV line as compared to 400 kV line is?

Last Answer : The X:R ratio of 220 kV line as compared to 400 kV line is smaller.

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 :  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 single phase transformer rated at 3000 kVA, 69 kV 4.16 kV, 60 Hz has a total internal impedance Zp of 127 ohm, referred to the primary side. Calculate the primary current if the secondary is accidentally short circuited.  (A) 43.5 A (B) 543 A (C) 9006 A (D) 721 A

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

Last Answer : 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 2280 MW

Description : A 10 kVA, 400 V/200 V single phase transformer with 10% impedance draws a steady short-circuit line current of   (a) 250A (b) 50 A (c) 150 A (d) 350 A

Last Answer : A 10 kVA, 400 V/200 V single phase transformer with 10% impedance draws a steady short-circuit line current of 250A

Description : A loss less line terminated with its surge impedance has

Last Answer : A loss less line terminated with its surge impedance has flat voltage profile.

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

Description :  Which of the following is the most important element of Project Management Plan that is useful in HR Planning process: A. Risk Management activities B. Quality Assurance activities C. Activity Resource requirements D. Budget Control activities

Last Answer : C. Activity Resource requirements

Description : As per chart on energy consumption the supply unit of furnace oil is ……… a. kWh c. kV b. kg. d. Watts

Description : As per pie chart on energy consumption the supply unit of the electricity is……….. a. kWh c. kV b. kg. d. Watts

Description : 99. As per chart on energy consumption the supply unit of furnace oil is ……… a. kWh c. kV b. kg. d. Watts

Description : 95. As per pie chart on energy consumption the supply unit of the electricity is……….. a. kWh c. kV b. kg. d. Watts

Description : The basic unit ofa worksheet into which you enter data in Excel is called a– (A) tab (B) cell (C) box (D) range (E) None of these

Description : Which of the following precautions should be taken when troubleshooting various power circuits using a common solenoid-type mechanical voltage tester (wiggins)? A. Never use this tester on circuits greater ... voltage expected in the circuit in order to prevent damage from an off-scale reading.

Description : Two transformers of identical voltages but different capacities are operated in parallel, for satisfactory load sharing: a) Impedances should be equal b) Per unit impedance must be equal c) per unit impedance and X/R ratio must be equal d) Impedance and X/R ratio must be equal

Description : Two transformers operating in parallel will share the load depending upon their (A) Rating. (B) Leakage reactance. (C) Efficiency. (D) Per-unit impedance.

Last Answer : Ans: A Transformers having higher kVA rating will share more load.

Description : Air blast circuit breakers for 400 kV power system are designed to operate in (a) 100 microsecond (b) 50 millisecond (c) 0.5 sec (d) 0.1 sec

Last Answer : (b) 50 millisecond

Description : The p.u. parameter for a 500 MVA machine on its own base are: inertia, M = 20 p.u. ; reactance, X = 2 p.u. The p.u. values of inertia and reactance on 100 MVA common base, respectively, are (A) 4, 0.4 (B) 100, 10 (C) 4, 10 (D) 100, 0.4

Last Answer : The p.u. parameter for a 500 MVA machine on its own base are: inertia, M = 20 p.u. ; reactance, X = 2 p.u. The p.u. values of inertia and reactance on 100 MVA common base, respectively, are 100, 0.4

Description : What is the type of 220 kV circuit breaker?

Last Answer : 220 kV, SF6 breaker, single pole, puffer type.

Description : What are the main parts of 220 kV Circuit Breaker?

Last Answer : Pole column filled with SF6 Pneumatic drive system with compressed air circuit Control cubicle unit

Description : A 3-phase circuit breaker is rated at 1250 A, 2000 MVA, 33 kV, 4s. Its making current capacity will be   (a) 35 kA (b) 89 kA (c) 79 kA (d) 69 kA

Last Answer : Air blast circuit breakers for 400 kV power system are designed to operate in 50 millisecond.

Description : A consumer consumes. 600 kWh per day at a load factor of 0.40. If the consumer increases the load factor of 0.70 without increasing the maximum demand, what is the consumption of energy in kWh?

Last Answer : A consumer consume. 600 kWh per day at a load factor of 0.40. If the coneumer increases the load factor of 0.70 without increasing the maximum demand, 1050 kWh is the consumption of energy in kWh.

Description : A final amplifier of a radio transmitter draws 250 mA of plate current when the plate supply voltage is 1400 volts. If the plate circuit efficiency is 80% and the transmitter is connected to an antenna having a feed impedance of 70 ohms, ... at the feed-point? A. 4.0 A B. 2.2 A C. 1.25 A D. 2.0 A

Last Answer : D. 2.0 A

Description : During unit operation can we have one UT feeding both unit 6.6 kV loads?

Last Answer : No, logically prevented.

Description : If a cable of homogeneous insulation has a maximum stress of 10 kV/mm, then the dielectric strength of insulation should be (a) 5 kV/mm (b) 10 kV/mm (a) 15 kV/mm (d) 30 kV/mm

Last Answer : (b) 10 kV/mm

Description : Dielectric strength of rubber is around (a) 5 kV/mm (b) 15 kV/mm (c) 30 kV/mm (d) 200 kV/mm

Last Answer : (c) 30 kV/mm

Description : Oil-filled cable has a working stress of __________ kV/mm (A) 10 (B) 12 (C) 13 (D) 15

Last Answer : Ans: D This is defined by dielectric strength of mineral oil i.e. 15 kV/mm.

Description : Common base configuration is little used because A) It has low input impedance B) It has high input impedance C) It does not heat up D) It has very high gain.

Last Answer : A) It has low input impedance

Description : Compare BJT common base configuration with common collector configuration on the basis of (i) Current gain (ii) Voltage gain (iii) Input impedance (iv) Output impedance

Last Answer : Parameter Common Base Common Collector Current gain Low (About 1) High (1+β) Voltage gain High 1  Input impedance  Low High Output impedance High Low

Description : 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

Last Answer : For 11 kV line the capacitance per km per phase will be of the order of: 0.01 Farad

Description : What is the full form of OFA ?

Last Answer : The full form of OFA Old Faujians Association.