Consider a distribution feeder, with  ratio of 5. At the receiving end, a 350 kVA load is connected. The maximum voltage drop will occur from the sending end to the receiving end, when the power factor of the load is ________ (round off to three decimal places).

Using shunt capacitors, the power factor of a 3 -phase, 4 kV induction motor (drawing 390 kVA at 0.77 pf lag) is to be corrected to 0.85 pf lag. The line current of the capacitor bank, in A, is _________  (round off to one decimal place).

The figure shows the single line diagram of a 4-bus power network. Branches , , and  have impedances , and  per-unit (pu), respectively, where , with  and . The current drawn from each load bus (marked as arrows) is equal to  pu, where . If the network is to operate with minimum loss, the branch that should be opened is

For the three-bus lossless power network shown in the figure, the voltage magnitudes at all the buses are equal to 1 per unit , and the differences of the voltage phase angles are very small. The line reactances are marked in the figure, where , and  are strictly positive. The bus injections  and  are in pu. If , where , and the real power flow from bus 1 to bus 2 is , then which one of the following options is correct?

A  line of length  has the following parameters:

Resistance,

Inductance, ;

Capacitance,

The line is represented by the nominal-  model. With the magnitudes of the sending end and the receiving end voltages of the line (denoted by  and , respectively) maintained at , the phase angle difference  between  and  required for maximum possible active power to be delivered to the receiving end, in degree is ________ (Round off to 2 decimal places).

The geometric mean radius of a conductor, having four equal strands with each strand of radius ‘𝑟’, as shown in the figure below, is

If only 5% of the supplied power to a cable reaches the output terminal, the power loss in the cable, in decibels, is _________. (round off to nearest integer)

Two single-core power cables have total conductor resistances of 0.7 Ω and 0.5 Ω, respectively, and their insulation resistances (between core and sheath) are 600 MΩ and 900 MΩ, respectively. When the two cables are joined in series, the ratio of insulation resistance to conductor resistance is ______

An alternator with internal voltage of . and synchronous reactance of 0.4 p.u is connected by a transmission line of reactance 0.1 p.u. to a synchronous motor having synchronous reactance 0.35 pu. and internal voltage of  If the real power supplied by the altemator is 0.866 p.u, then  is …………… degrees. (Round off to 2 decimal places) (Machines are of non-salient type. Neglect resistances)

In the figure shown, self-impedances of the two transmission Iines are 1.5j p.u each, and  is the mutual impedance. Bus voltages shown in the figure are in p.u. Given that , the maximum steady-state real power that can be transferred in p.u from Bus-1 to Bus-2 is

A lossless transmission line with 0.2 pu reactance per phase uniformly distributed along the length of the line, connecting a generator bus to a load bus, is protected up to 80 % of its length by a distance relay placed at the generator bus. The generator terminal voltage is 1 pu. There is no generation at the load bus. The threshold pu current for operation of the distance relay for a solid three phase-to-ground fault on the transmission line is closest to:

Bus 1 with voltage magnitude  is sending reactive power  towards bus 2 with voltage magnitude  through a lossless transmission line of reactance X. Keeping the voltage at bus 2 fixed at 1 pu, magnitude of voltage at bus 1 is changed, so that the reactive power  sent from bus 1 is increased by

20%. Real power flow through the line under both the conditions is zero. The new value of the voltage magnitude, , in pu (rounded off to 2 decimal places), at bus 1 is __________.

A three-phase 50Hz, 400kV transmission line is 300 km long. The line inductance is 1mH/phase and capacitance 0.01µF/km per phase. The line is under open circuit condition at receiving end and energized with 400kV at sending end, the receiving end line voltage is KV (round off to two decimal places) will be ______

In the single machine infinite bus system shown below, the generator is delivering the real power of 0.8 pu at 0.8 power factor lagging to the infinite bus. The power angle of the generator in degrees (round off to one decimal place) is _________.

Consider a lossy transmission line with and as the sending and receiving end voltages, respectively. Z and X are the series impedance and reactance of the line, respectively. The steady-state stability limit for the transmission line will be

Consider the two bus power system network with given loads as shown in the figure. All the values shown in the figure are in per unit. The reactive power supplied by generator  and  are and respectively. The per unit values of and line reactive power loss respectively are

A load is supplied by a 230 V, 50 Hz source. The active power P and the reactive power Q consumed by the load are such that .and A capacitor connected across the load for power factor correction generates 1 kVAR reactive power. The worst case power factor after power factor correction is

The nominal- circuit of a transmission line is shown in the figure.                 

Impedance  and reactance. The magnitude of the characteristic impedance of the transmission line, in , is ______________ . (Give the answer up to one decimal place)

Consider an overhead transmission line with 3-phase, 50 Hz balanced system with conductors located at the vertices of an equilateral triangle of length  as shown in figure below. The resistances of the conductors are neglected. The geometric mean radius (GMR) of each conductor is 0.01 m. Neglecting the effect of ground, the magnitude of positive sequence reactance in  (rounded off to three decimal places ) is ___________

A 3-phase, 50 Hz generator supplies power of 3MW at 17.32 kV to a balanced 3-phase inductive load through an overhead line. The per phase line resistance and reactance are  and  respectively. If the voltage at the generator terminal is 17.87 kV, the power factor of the load is ___________ .

A three-phase cable is supplying 800kW and 600 kVAr to an inductive load. It is intended to supply an additional resistive load of 100kW through the same cable without increasing the heat dissipation in the cable, by providing a three-phase bank of capacitors connected in star across the load. Given the line voltage is 3.3kV, 50Hz, the capacitance per phase of the bank, expressed in microfarads, is _______________.  

A single-phase transmission line has two conductors each of 10 mm radius. These are fixed at a center-to-center distance of 1m in a horizontal plane. This is now converted to a three-phase transmission line by introducing a third conductor of the same radius. This conductor is fixed at an equal distance D from the two single-phase conductors. The three phase line is fully transposed. This positive sequence inductance per phase of the three-phase system is to be 5% more than that of the inductance per conductor of the single-phase system. The distance D, in meters, is_________________.

The inductance and capacitance of a 400kV, three-phase, 50 Hz lossless transmission line are 1.6 mH/km/phase and 10 mF/km/phase respectively. The sending end voltage is maintained at 400kV. To maintain a voltage of 400kV at the receiving end, when the line is delivering 300MW load, the shunt compensation required is

At no load condition, a 3-phase, 50Hz, losses power transmission line has sending-end and receiving-end voltages of 400kV and 420kV respectively. Assuming the velocity of travelling wave to be the velocity of light, the length of the line, in km, is______________.

The power consumption of an industry is 500 kVA, at 0.8 p.f. lagging. A synchronous motor is added to raise the power factor of the industry to unity. If the power intake of the motor is 100 kW, the p.f. of the motor is_______________.

Consider a HVDC link which uses thyristor based line- commutated converter as shown in the figure. For a power flow of 750 MW from system 1 to system 2, the voltages at the two ends, and the current are given by:  =500 kV,   and I=1.5 kA. If the direction of power flow is to be reversed (that is from system 2 to system 1) without changing the electrical connections, then which one of the following combinations is feasible?

A composite conductor consists of three conductors of radius R each. The conductors are arranged as shown below. The geometric mean radius (GMR) (in cm) of the composite conductor is kR.  The value of k is ____________.

The undesirable property of an electrical insulating material is

A distribution feeder of 1km length having resistance, but negligible reactance, is fed from both the ends by 400V, 50Hz balanced sources. Both voltage source  are in phase. The feeder supplies concentrated loads of unity power factor as shown in the figure.

The contributions of  and  in 100A current supplied at location P respectively, are

A two bus power system shown in the figure supplies load of 1.0 + j0.5 p.u

The values of  in p.u. and  respectively are

A single phase induction motor draws 12 MW power at 0.6 lagging power. A capacitor is connected in parallel to the motor to improve the power factor of the combination of motor and capacitor to 0.8 lagging. Assuming that the real and reactive power drawn by the motor remains same as before, the reactive power delivered by the capacitor in MVAR is ______________.         

A three phase star-connected load is drawing power at a voltage of 0.9 pu and 0.8 power factor lagging. The three phase base power and base current are 100 MVA and 437.38 A respectively. The line-to-line load voltage in kV is______________.

Shunt reactors are sometimes used in high voltage transmission systems to

The horizontally placed conductors of a single phase line operating at 50Hz are having outside diameter of 1.6cm, the spacing between centers of the conductors is 6m. The permittivity of free space is F/m. The capacitance to ground per kilometer of each line is

In a long transmission line with r, l, g and c are the resistance, inductance, shunt conductance and capacitance per unit length, respectively, the condition for distortion less transmission is

For a 400 km long transmission line, the series impedance is  and the shunt admittance is  μmho/km. The magnitude of the series impedance  of the equivalent  circuit of the transmission line is ____________.

The complex power consumed by a constant-voltage load is given by , where  and .A compensating shunt capacitor is chosen such that , where Q is the net reactive power consumed by the capacitor-load combination. The reactive power (in kVAR) supplied by the capacitor is ____________.

For the system shown below,  and  are complex power demands at bus 1 and bus 2 respectively. If , the VAR rating of the capacitor  connected at bus 2 is

A nuclear power station of 500MW capacity is located at 300km away from a load center. Select the most suitable power evacuation transmission configuration among the following options

For enhancing the power transmission in a long EHV transmission line, the most preferred method is to connect a        

Power is transferred from system A to system B by an HVDC link as shown in the figure. If the voltages  and  are as indicated in the figure and l > 0, then

Consider a step voltage wave of magnitude 1pu travelling along a lossless transmission line that terminates in a reactor. The voltage magnitude across the reactor at the instant the travelling wave reaches the reactor is

Consider two buses connected by an impedance of. The bus 1 voltage is 10030°V, and bus 2 voltage is . The real and reactive power supplied by bus 1, respectively are

A 50Hz synchronous generator is initially connected to a long lossless transmission line which is open circuited at the receiving end. With the field voltage held constant, the generator is disconnected from the transmission line. Which of the following may be said about the steady state terminal voltage and field current of the generator?

Consider a three-phase, 50Hz, 11kV distribution system. Each of the conductors is suspended by an insulator string having two identical porcelain insulators. The self capacitance of the insulator is 5 times, the shunt capacitance between the link and the ground, as shown in the figure. The voltages across the two insulators are

Consider a three-core, three-phase, 50Hz, 11kV cable whose conductors are denoted as R,Y, and B in the figure. The inter-phase capacitance () between each pair of conductors is and the capacitance between each line conductor and the sheath is. The per-phase charging current is

For a fixed value of complex power flow in a transmission line having a sending end voltage V, the real power loss will be proportional to

Match the items in List-I with the items in List-II and select the correct answer using the codes given below the lists.

Three generators are feeding a load of 100 MW. The details of the generators are

In the event of increased load power demand, which of the following will happen?

An extra high voltage transmission line of length 300 km can be approximated by a lossless line having propagation constant β=0.00127 radians per km. Then the percentage ratio of line length to wavelength will be given by

A lossless 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

Single line diagram of a 4-bus single source distribution system is shown below. Branches and have equal impedances. The load current values indicated in the figure are in per unit.

Distribution Company’s policy requires radial system operation with minimum loss, this can be achieved by opening of the branch

Consider the transformer connections in a part of a power system shown in the figure. The nature of transformer connections and phase shifts are indicated for all but one transformer. Which of the following connections, and the corresponding phase shift , should be used for the transformer between A and B?

Two regional systems, each having several synchronous generators and loads are interconnected by an ac line and a HVDC link as shown in the figure. Which of the following statements is true in the steady state:

Consider a bundled conductor of an overhead line, consisting of three identical sub-conductors placed at the corners of an equilateral triangle as shown in the figure. If we neglect the charges on the other phase conductors and ground, and assume that spacing between sub-conductors is much larger than their radius, the maximum electric field intensity is experienced at        

The total reactance and total susceptance of a lossless overhead EHV line, operating at 50 Hz. are given by 0.045pu and 1.2pu respectively. If the velocity of wave propagation is , then the approximate length of the line is

Consider the two power systems shown in figure A below, which are initially not interconnected, and are operating in steady state at the same frequency. Separate load flow solutions are computed individually for the two systems, corresponding to this scenario. The bus voltage phasors so obtained are indicated on figure A. These two isolated systems are now interconnected by a short transmission line as shown in figure B, and it is found that.

The bus voltage phase angular difference between generator bus X and generator bus Y after the interconnection is

A 230 V (Phase). 50 Hz, three-phase, 4-wire system has a phase sequence ABC. A unity power-factor load of 4 kW is connected between phase A and neutral N. It is desired to achieve zero neutral current through the use of a pure inductor and a pure capacitor in the other two phases. The value of inductor and capacitor is

The concept of an electrically short, medium and long line is primarily based on the

An HVDC link consists of rectifier, inverter transmission line and other equipment’s. Which one of the following is true for this link?

A 400V, 50 Hz, three phase balanced source supplies power to a star connected load whose rating is kVA, 0.8 pf (lag).  The rating (in kVAR) of the delta connected (capacitive) reactive power bank necessary to bring the pf to unity is

The A, B, C, D constants of a 220 kV line are:  , , . If the sending end voltage of the line for a given load delivered at nominal voltage is 240 kV, then % voltage regulation of the line is

A single phase transmission line and a telephone line are both symmetrically strung one below the other, in horizontal configurations, on a common tower.  The shortest and longest distances between the phase and telephone conductors are 2.5 m and 3 m respectively. The voltage (volt/km) inducted in the telephone circuit, due to 50 Hz current of 100 amps in the power circuit is

An 800 kV transmission line has a maximum power transfer capacity P, on the operated at 400 kV with the series reactance unchanged, the new maximum power transfer capacity is approximately

The insulation strength of an EHV transmission line is mainly governed by

High Voltage DC (HVDC) transmission is mainly used for

At an industrial sub-station with a 4 MW load, a capacitor of 2 MVAR is installed to maintain the load power factor at 0.97 lagging. If the capacitor goes out of service, the load power factor becomes

The rated voltage of a 3-phase power system is given as

The phase sequence of the 3-phase system shown in Figure is

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

A 110 kV, single core coaxial, XLPE insulated power cable delivering power at 50 Hz, has a capacitance of 125nF/km. If the dielectric loss tangent of XLPE is , the dielectric power loss in this cable in W/km is

A lightning stroke discharges impulse current of 10 kA (peak) on a 400 kV transmission line having surge impedance of 250Ω. The magnitude of transient over-voltage traveling waves in either direction assuming equal distribution form the point of lightning strike will be

The generalized circuit constants of a 3-phase, 220 kV rated voltage, medium length transmission line are

If the load at the receiving end is 50 MW at 220 kV with a power factor of 0.9 lagging, the magnitude of line to line sending end voltage should be

A new generator having  [equivalent to (1.212+j0.70) p.u. and synchronous reactanceof 1.0 p.u. on the system base, is to be connected to a bus having voltage  in the existing power system. This existing power system can be represented by Thevenin’s voltage  in series with Thevenin’s impedance .  The magnitude of the bus voltage  of the system in pu will be

Bundled conductors are mainly used in high voltage overhead transmission lines to

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 of A.C. line

A balanced delta connected load of (8+j6) Ω per phase is connected to a 400 V, 50 Hz, 3-phase supply lines. If the input power factor is to be improved to 0.9 by connecting a bank of star connected capacitors the required kVAR of the bank

The ABCD parameters of a 3-phase overhead transmission line are ,  and . At no-load condition a shunt inductive reactor is connected at the receiving end of the line to limit the receiving end voltage to be equal to the sending end voltage. The ohmic value of the reactor is

A surge of 20 kV magnitude travels along a lossless cable towards its junction with two identical lossless overhead transmission lines. The inductance and the capacitance of the cable are 0.4mH and 0.5µF per km. The inductance and capacitance of the overhead transmission lines are 1.5mH and 0.015µF per km.  The magnitude of the voltage at the junction due to surge is

A dc distribution system is shown in Figure with load currents as marked. The two ends of the feeder are fed by voltage sources such that, the value of the voltage for a minimum voltage of 220V at any point along the feeder is

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 unit positive sequence impedance of the line based on 100 MVA and 11 kV is j 0.2.  The line-to-line voltage at the load terminals is measured to be less than 11 kV.  The total reactive power to be injected at the terminals of the load to increase the line-to-line voltage at the load terminals to 11 kV is

Consider a long, two-wire line composed of solid round conductors. The radius of both conductors is 0.25 cm and the distance between their centers is 1m. If this distance is doubled, then the inductance per unit length

Consider a power system with three identical generators. The transmission losses are negligible. One generator () has a speed governor which maintains its speed constant at the rated value, while the other generators (and ) have governors with a drop of 5%.If the load of the system is increased, then in steady state.

A long wire composed of a smooth round conductor runs above and parallel to the ground (assumed to be a large conducting plane). A high voltage exists between the conductor and the ground. The maximum electric stress occurs at

A transmission line has a total series reactance of 0.2 pu. Reactive power compensation is applied at the midpoint of the line and it is controlled such that the midpoint voltage of the transmission line is always maintained at 0.98 pu. If voltage at both ends of the line are maintained at 1.0 pu, then the steady state power transfer limit of the transmission line is

A long lossless transmission line has a unity power factor (UPF) load at the receiving end and an ac voltage source at the sending end (Figure). The parameters of the transmission line are as follows:

Characteristic impedance , propagation constant , and length. The equation relating sending and receiving end questions is

Compute the maximum power that can be transferred to the UPF load at the receiving end if .

A 50 Hz balanced three-phase, Y-connected supply is connected to a balanced three phase Y-connected load.  If the instantaneous phase-α of the supply voltage is and the phase-α of the load current is , the instantaneous three-phase power is

A lossless radial transmission line with surge impedance loading

Consider the model shown in Figure of a transmission line with a series capacitor at its mid-point.  The maximum voltage on the line is at the location

A power system has two synchronous generators.  The Governor-turbine characteristics corresponding to the generators are.  Where f denotes the system frequency in Hz, and  and  are, respectively, the power outputs (in MW) of turbines 1 and 2 assuming the generators and transmission network to be lossless, the system frequency for a total load of 400 MW is        

The conductors of a 10 km long, single phase, two wire line are separated by a distance of 1.5m.  The diameter of each conductor is 1 cm.  If the conductors are of copper, the inductance of the circuit is

A 132 kV transmission line AB is connected to a cable BC.  The characteristic impedances of the overhead line and the cable are 400Ω and 80Ω respectively.  Assume that these are purely resistive. A 250 kV switching surge travels from A to B.        

(a) Calculate the value of this voltage surge when it first reaches C.

(b) Calculate the value of the reflected component of this surge when the first reflection reaches A.

(c) Calculate the surge current in the cable BC.

Out of the considerations (i) and (iv) listed below

(i) No distance limitation related to steady state stability

(ii) No reactive power requirement from the system at the two terminals

(iii) No substantial effect fault level of the two systems at the terminals in spite of the interconnection

(iv) No corona problems

The considerations, which constitute advantage of HVDC transmission, are

The corona loss on a particular system at 50 Hz is 1kW/km per phase. The corona loss at 60 Hz would be

A 275kV, 3-phase, 50 Hz, 400km lossless line has following parameters:         

, line charging susceptance  micro-Siemens/km

(a) Calculate the receiving end voltage on open circuit using justifiable assumptions.

(b) What load at the receiving end will result in a flat voltage profile on the line?

(c) If the flat voltage profile is to be achieved at 1.2 times the loading in (b), what will be the nature and quantum of uniformly distributed compensation required

An overhead line having a surge impedance of 400Ω is connected in series with an underground cable having a surge impedance of 100Ω. If a surge of 50kV travels from the line end towards the line-cable junctions, the value of the transmitted voltage wave at the junction is:

The load carrying capability of a long AC transmission line is:

Corona losses are minimized when