Determine the correctness or otherwise of the following Assertion [a] and the Reason [r]. Assertion: Fast decoupled load flow method gives approximate load flow solution because it uses several assumptions. Reason: Accuracy depends on the power mismatch vector tolerance.

Both [a] and [r] are true and [r] is the correct reason for [a].

Both [a] and [r] are true and [r] is not the correct reason for [a].

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

power transmitted over the line

Shunt reactors are sometimes used in high voltage transmission systems to

compensate for the voltage drop in the line under heavily loaded condition

limit the short circuit current through the line

compensate for the series reactance of the line under heavily loaded condition

limit over-voltages at the load side under lightly loaded condition

compensate for the voltage drop in the line under heavily loaded condition

A single-phase load is supplied by a single-phase volt age source. If the current flowing from the load to the source is 10 150 A and if the voltage at the load terminals is 100 60 V, then the

load delivers real power and delivers reactive power.

load absorbs real power and delivers reactive power.

load absorbs real power and absorbs reactive power.

load delivers real power and delivers reactive power.

load delivers real power and absorbs reactive power.

In a high voltage dc transmission scheme, reactive power is needed both for rectifier at the sendingend and, for inverter at the receiving-end. During the operation of such a dc link, rectifier receives

leading reactive power and the inverter supplies lagging reactive power

lagging reactive power and the inverter supplies leading reactive power

leading reactive power and the inverter supplies lagging reactive power

lagging reactive power and the inverter supplies lagging reactive power

leading reactive power and the inverter supplies leading reactive power.

The main consideration for higher and higher operating voltage of transmission is to

increase efficiency of transmission

increase power transfer capability

The transient stability of the power system can be effectively improved by

increasing the turbine valve opening

single pole switching of circuit breakers

increasing the turbine valve opening

249 + Mcqs in Power systems miscellaneous in Power Systems Page 1 McqOptions

1.	A power system has two synchronous generators. The governor-turbine characteristics orresponding to the generators are P₁ = 50(50 ), P₂ = 100(51 ). where f denotes the system frequency in Hz and P₁ and P₂ are respectively, the power outputs (in MW) of turbines 1 and 2. Assuming the generat or s and transmission network to be lossless, the system frequency for a total load of 400 MW is __________ Hz
A.	0.48 Hz.
B.	48 Hz.
C.	4.08 Hz.
D.	4.8 Hz.
Answer» C. 4.08 Hz.

Discussion

2.	Determine the correctness or otherwise of the following Assertion [a] and the Reason [r]. Assertion: Fast decoupled load flow method gives approximate load flow solution because it uses several assumptions. Reason: Accuracy depends on the power mismatch vector tolerance.
A.	Both [a] and [r] are true and [r] is the correct reason for [a].
B.	Both [a] and [r] are true and [r] is not the correct reason for [a].
C.	Both [a] and [r] are false.
D.	[a] is false and [r] is true.
Answer» E.

Discussion

3.	The fuel cost functions of two powr plants are Plant P₁ : C₁ = 0.05 Pg ₁ + APg₁ + B Plant P₂ : C₂ = 0.10 Pg ₂ + APg₂ + 2B Where, P_g1 and P_g2 are the generated powers of two plants, and A and B are the constants. If the two plants optimally share 1000 MW load at increamental fuel cost of 100 Rs/MWh, the ratio of load shared by plants P₁ and P₂ is
A.	1: 4
B.	2: 3
C.	3: 2
D.	4: 1
Answer» E.

Discussion

4.	If a 75 MVA, 10 kV synchronous generator has X_d = 0.4 p.u, then X_d value (in p.u.) to a base of 100 MVA, 11 kV is ___________
A.	44
B.	0.44
C.	4.4
D.	0.04
Answer» C. 4.4

Discussion

5.	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 distortionless transmission is
A.	rc = lg
B.	r =
C.
D.	rg = lc
E.	g =
Answer» B. r =

Discussion

6.	A cable has following characteristics: L = 0.201 H/m and C = 196.2 p/F/m. The velocity of wave propagation through the cable is ________ m/s
A.	1592.4
B.	15924
C.	159.24
D.	15.924
Answer» D. 15.924

Discussion

7.	When a line-to-ground fault occurs, the current in the phase is 100 A. The zero sequence current in this case will be _______ A
A.	1.4996
B.	149.96
C.	149.96
D.	14900
Answer» D. 14900

Discussion

8.	A three phase 50 Hz line consists of three conductors each of diameter 21 mm. The spacing between the conductors as follows: A B = 3m, B C = 5m, C A = 3.6 m If the line operates at 132 kV, the reactive voltampere generatd by the line per km is _______kVAr
A.	51703 VAr.
B.	5.1703 VAr.
C.	517.03 VAr.
D.	5170.3 VAr.
Answer» B. 5.1703 VAr.

Discussion

9.	If the sheath resistance is 2.14 /km and that of the conduct or is 0.1625 /k m, and mutual inductance of the shealth is 3.13 10⁷ H/m. When the cable is 2 km long and supply is 50 Hz, the ratio of sheath loss to core loss of the cable will be_______
A.	277
B.	0.277
C.	0.0277
D.	27.7
Answer» D. 27.7

Discussion

10.	A 50 Hz alternator is rated 500 MVA, 20 kV, with X_d = 1.0 per unit and X_"d = 0.2 per unit. It supplies a purely resistive load of 400 MW at 20 kV. The load is connected directly across the generator terminals when a symmetrical fault occurs at the load terminals. The initial rms current in the generator in per unit is __________
A.	3.022
B.	3.22
C.	53.26
D.	542.5
Answer» C. 53.26

Discussion

11.	A single line to ground fault occurs on an unloaded generator in phase a. If x_d = x₂ = 0.25 p.u., x₀ = 0.15 p.u., reactance connected in the neutral, x_n = 0.05 p.u. and the initial prefault voltage is 1.0 p.u., then the magnitude of the fault current will be ________ p.u.
A.	375
B.	3.75
C.	37.5
D.	0.375
Answer» D. 0.375

Discussion

12.	A power system has two generating plants and the power is being dispatched economically with P₁ = 125 MW and P₂ = 250 M W. The loss coefficients are B₁₁ = 0.10 102 MW¹ , B₁₂ = 0.01 10² MW¹, B₂₂ = 0.13 10² MW¹to raise the total load on the system by 1 MW will cost an additional 200 per hour. The penalty factor for plant 1 will be __________
A.	1.25
B.	12.5
C.	1.25
D.	0.125
Answer» D. 0.125

Discussion

13.	A source v_s (t) =V cos 100 t has an internal impedance of (4 + j3) If a purely resistive load connected to this source has to extract the maximum power out of the source, its value in should be
A.	3
B.	4
C.	5
D.	7
Answer» D. 7

Discussion

14.	The following data pertain to two alternators working in parallel and supplying a total load of 80 MW: Machine 1: 40 MVA with 5% speed regulation Machine 2: 60 MVA with 5% speed regulation The load sharing between machines 1 and 2 will be
A.
B.	40 MW 40 MW
C.	30 MW 50 MW
D.	32 MW 48 MW
Answer» D. 32 MW 48 MW

Discussion

15.	A fault occuring at the terminals of an unloaded synchronous generator opetaing at its rated voltage has resulted in the following values of the current and voltage. I_a0 = j 2.37 p.u. I_a1 = j 3.05 p.u. I_a2 = j 0.68 p.u. V_a0 = V_a1 = V_a2 = j 2.37 p.u. The fault that has occurred is
A.	L L fault
B.	L L G fault
C.	L G fault
D.	none of these
Answer» C. L G fault

Discussion

16.	The following sequence currents were recorded in a power system under a fault condition: I_positive = j 1.653 p.u. I_negative = j 0.5 p.u. I_zero = j 1.153 p.u. The fault is
A.	line to ground
B.	three phase
C.	line to line ground
D.	line to line
Answer» D. line to line

Discussion

17.	What is the posit ive sequence currents in a three phase system, when the original phasors at which are I_a = (12 + j6), I_b = (12 j 12), I_c = ( 15 + j10) ?
A.	14.8 Amp.
B.	16.2 Amp.
C.	18 Amp.
D.	10.2 Amp
Answer» B. 16.2 Amp.

Discussion

18.	A two-phase load draws the following phase currents: i₁ (t) = I_m sin( t ₁ ), i₂ (t) = I_m cos( t ₂). These currents are balanced if ₁ is equal to
A.
B.
C.
D.
Answer» E.

Discussion

19.	The sequence components of the fault current are as follows: I_positive = j1.5 pu, I _negative = j0.5 pu, I_zero = j1 pu. The type of fault in the system is
A.	LG
B.	LL
C.	LLG
D.	LLLG
Answer» D. LLLG

Discussion

20.	What is the utilization factor of a power station which supplies the following loads ? Load A: Motor load of 200 kW between 10 AM to 7 PM Load B: Lighting load of 100 k W bet ween 7 PM to 11 PM Load C: Pumping load of 110 kW between 3 PM to 10 AM
A.	1.60
B.	1.32
C.	1.00
D.	2.56
Answer» C. 1.00

Discussion

21.	For a power system network with n nodes, Z₃₃ of its bus impedance matrix is j0.5 per unit. The voltage at node 3 is 1.3 10 per unit. If a capacitor having reactance of j3.5 per unit is now added to the network between node 3 and the reference node, the current drawn by the capacitor per unit is
A.	0.325 100
B.	0.325 80
C.	0.371 100
D.	0.433 80
Answer» E.

Discussion

22.	Base load power plants are P wind farms Q run-of-river plants R nuclear power plants S diesel power plants
A.	P, Q & S only
B.	P, R & S only
C.	P, Q & R only
D.	Q and R only
Answer» D. Q and R only

Discussion

23.	A single circuit 50 Hz, 3 transmission line has the following parameters per km. R = 0.2 , L = 1.3 mH, C = 0.01 F The efficiency of the line, if the line is 120 km long and deliver 40 mW at 132 kV and 0.8 pf lagging will be _________%
A.	0.926%
B.	9.26%
C.	92.6%
D.	926%
Answer» D. 926%

Discussion

24.	Buses for load flow studies are classified as (i) the load bus (ii) the generator bus (iii) the slace bus The correct combination of the pair of quantities specified having their usual meaning for different buses is Load Bus Generator Slace bus
A.	P, \|V\| P, Q P,
B.	P, Q P, \|V\| \|V\| ,
C.	\|V\|, Q P, P, Q
D.	P, Q, \|V Q,
Answer» C. \|V\|, Q P, P, Q

Discussion

25.

The incremental costs (in Rupees/M Wh) of operating two generating units are functions of their respective powers P₁ and P₂ in MW, and are given by
dC₁ = 0.2P₁ + 50; dC₂ = 0.24P₂ + 40;
dP₁ dP₂

Where
20 MW P₁ 150 MW
20 MW P₂ 150 MW
For a certain load demand, P₁ and P₂ have been chosen such that dC₁ /dP₁ = 76 Rs/MWh and dC₂/dP₂ = 68.8 Rs/MWh. If the generations are rescheduled to minimize the total cost, then P₂ is __________.

A.

130

B.

1360

C.

1.036

D.

136.36

Answer» E.

Discussion

26.	A balanced three-phase voltage is applied to a star-connected induction motor, the phase to neutral voltage being V. The stator resistance, rotor resistance referred to the stator, stator leakage reactance, rotor leakage reactance refer red to the stator, and the magnet izing reactance are denoted by r_s, r_r, x_s, x_r and X_m, respectively. The magnitude of the starting current of the motor is given by
A.
Answer» B.

Discussion

27.	Out of the following plant categories (i) Nuclear (ii) Run-of-river (iii) Pump Storage (iv) Diesel the base load power plants are
A.	(i) and (ii)
B.	(ii) and (iii)
C.	(i), (ii) and (iv)
D.	(i), (ii) and (iv)
Answer» D. (i), (ii) and (iv)

Discussion

28.

Three generators are feeding a load of 100 MW. The details of the generators are given below.
Rating Efficiency Regulation
(MW) (%) (p.u) on 100 MVA base
Generator-1 100 20 0.02
Generator-2 100 30 0.04
Generator-3 100 40 0.03

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

A.

All the generators will share equal power

B.

Generat or -3 will share more power compared to Generator-1

C.

Generat or -1 will share more power compared to generator-2

D.

Generat or -2 will share more power compared to Generator-3

Answer» D. Generat or -2 will share more power compared to Generator-3

Discussion

29.	The total reactance and total susceptance of a lossless overhead EHV line, operating at 50 Hz, are given by 0.045 pu and 1.2 pu respectively. If the velocity of wave propagation is 3 10⁵ km/s, then approximate length of the line is
A.	122 km
B.	185 km
C.	222 km
D.	272 km
Answer» C. 222 km

Discussion

30.	The A, B, C, D constants of a 220 kV line are: A = D = 0.94 1 , B = 130 73 , C = 0.001 90 If 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.	5
B.	9
C.	16
D.	21
Answer» D. 21

Discussion

31.	Consider the economic dispatch problem for a power plant having two generating units. The fuel costs in Rs/MWh along with the generation limits for the two units are given below: C₁ (P₁) = 0.01P₁ + 30P₁ + 10; 100MW P₁ 150MW C₂ (P₂) = 0.05P₂ + 10P₂ + 10; 100MW P₂ 180MW The incremental cost (in Rs/MWh) of the power plant when it supplies 200 MW is _____.
A.	2.0
B.	0.20
C.	0.02
D.	20
Answer» E.

Discussion

32.	The concept of an electrically short, medium, and long line is primarily based on the
A.	nominal voltage of the line
B.	physical length of the line
C.	wavelength of the line
D.	power transmitted over the line
Answer» C. wavelength of the line

Discussion

33.	Shunt reactors are sometimes used in high voltage transmission systems to
A.	limit the short circuit current through the line
B.	compensate for the series reactance of the line under heavily loaded condition
C.	limit over-voltages at the load side under lightly loaded condition
D.	compensate for the voltage drop in the line under heavily loaded condition
Answer» D. compensate for the voltage drop in the line under heavily loaded condition

Discussion

34.	The fuel cost functions of two powr plants are
A.	1: 4
B.	2: 3
C.	3: 2
D.	4: 1
Answer» E.

Discussion

35.	A single-phase load is supplied by a single-phase volt age source. If the current flowing from the load to the source is 10 150 A and if the voltage at the load terminals is 100 60 V, then the
A.	load absorbs real power and delivers reactive power.
B.	load absorbs real power and absorbs reactive power.
C.	load delivers real power and delivers reactive power.
D.	load delivers real power and absorbs reactive power.
Answer» C. load delivers real power and delivers reactive power.

Discussion

36.	Power consumed by a balanced 3-phase, 3-wire load is measured by the two wattmeter method. The first wattmeter reads twice that of the second. Then the load impedance angle in radians is
A.	/12
B.	/8
C.	/6
D.	/3
Answer» D. /3

Discussion

37.	A 3-bus power system network consists of 3 transmission lines. The bus admittance matrix of the uncompensated system is
A.	j 7.0
B.	j 8.5
C.	j 7.5
D.	j 9.0
Answer» C. j 7.5

Discussion

38.	A generating station has a maximum demand of 50 MW, a load factor of 60%, a plant capacity factor of 45% and if the plant while running as per schedule, were fully loaded. The daily energy produced will be ________ MW
A.	7.20 M W.
B.	72.0 M W.
C.	0.720 M W.
D.	720 M W.
Answer» E.

Discussion

39.	For a power system network with n nodes, Z
A.	0.325 100
B.	0.325 80
C.	0.371 100
D.	0.433 80
Answer» E.

Discussion

40.	Base load power plants are
A.	P, Q & S only
B.	P, R & S only
C.	P, Q & R only
D.	Q and R only
Answer» D. Q and R only

Discussion

41.	If the sheath resistance is 2.14 /km and that of the conduct or is 0.1625 /k m, and mutual inductance of the shealth is 3.13 10
A.	277
B.	0.277
C.	0.0277
D.	27.7
Answer» D. 27.7

Discussion

42.	The insulation resistance of a cable of length 10 km is 1 M . For a length of 100 km of the same cable, the insulation resistance will be _______M
A.	1.01
B.	10
C.	1
D.	0.1
Answer» E.

Discussion

43.	The per unit impedance of a 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 __________
A.	30.0
B.	0.03
C.	0.30
D.	3.00
Answer» D. 3.00

Discussion

44.	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 Megawatts, would be _________
A.	461
B.	641
C.	416
D.	164
Answer» D. 164

Discussion

45.	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. The consumpt ion of energy in kWh is______
A.	1050 kWh
B.	1500 kWh
C.	1005 kWh
D.	5010 kWh
Answer» B. 1500 kWh

Discussion

46.	In a high voltage dc transmission scheme, reactive power is needed both for rectifier at the sendingend and, for inverter at the receiving-end. During the operation of such a dc link, rectifier receives
A.	lagging reactive power and the inverter supplies leading reactive power
B.	leading reactive power and the inverter supplies lagging reactive power
C.	lagging reactive power and the inverter supplies lagging reactive power
D.	leading reactive power and the inverter supplies leading reactive power.
Answer» B. leading reactive power and the inverter supplies lagging reactive power

Discussion

47.	The main consideration for higher and higher operating voltage of transmission is to
A.	increase efficiency of transmission
B.	reduce power losses
C.	increase power transfer capability
D.	both (a) and (b)
Answer» D. both (a) and (b)

Discussion

48.	Bulk power transmission over long HVDC lines are preferred, on account of
A.	low cost of HVDC terminals
B.	no harmonic problems
C.	minimum line power losses
D.	simple protection
Answer» C. minimum line power losses

Discussion

49.	The transient stability of the power system can be effectively improved by
A.	excitation control
B.	phase shifting transformer
C.	single pole switching of circuit breakers
D.	increasing the turbine valve opening
Answer» D. increasing the turbine valve opening

Discussion

50.	The sequence components of the fault current are as follows: I
A.	LG
B.	LL
C.	LLG
D.	LLLG
Answer» D. LLLG

Discussion

Explore topic-wise MCQs in Power Systems.

Determine the correctness or otherwise of the following Assertion [a] and the Reason [r]. Assertion: Fast decoupled load flow method gives approximate load flow solution because it uses several assumptions. Reason: Accuracy depends on the power mismatch vector tolerance.

If a 75 MVA, 10 kV synchronous generator has Xd = 0.4 p.u, then Xd value (in p.u.) to a base of 100 MVA, 11 kV 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 distortionless transmission is

A cable has following characteristics: L = 0.201 H/m and C = 196.2 p/F/m. The velocity of wave propagation through the cable is ________ m/s

When a line-to-ground fault occurs, the current in the phase is 100 A. The zero sequence current in this case will be _______ A

A three phase 50 Hz line consists of three conductors each of diameter 21 mm. The spacing between the conductors as follows: A B = 3m, B C = 5m, C A = 3.6 m If the line operates at 132 kV, the reactive voltampere generatd by the line per km is _______kVAr

If the sheath resistance is 2.14 /km and that of the conduct or is 0.1625 /k m, and mutual inductance of the shealth is 3.13 10 7 H/m. When the cable is 2 km long and supply is 50 Hz, the ratio of sheath loss to core loss of the cable will be_______

A single line to ground fault occurs on an unloaded generator in phase a. If xd = x2 = 0.25 p.u., x0 = 0.15 p.u., reactance connected in the neutral, xn = 0.05 p.u. and the initial prefault voltage is 1.0 p.u., then the magnitude of the fault current will be ________ p.u.

A source vs (t) =V cos 100 t has an internal impedance of (4 + j3) If a purely resistive load connected to this source has to extract the maximum power out of the source, its value in should be

The following data pertain to two alternators working in parallel and supplying a total load of 80 MW: Machine 1: 40 MVA with 5% speed regulation Machine 2: 60 MVA with 5% speed regulation The load sharing between machines 1 and 2 will be

A fault occuring at the terminals of an unloaded synchronous generator opetaing at its rated voltage has resulted in the following values of the current and voltage. Ia0 = j 2.37 p.u. Ia1 = j 3.05 p.u. Ia2 = j 0.68 p.u. Va0 = Va1 = Va2 = j 2.37 p.u. The fault that has occurred is

The following sequence currents were recorded in a power system under a fault condition: Ipositive = j 1.653 p.u. Inegative = j 0.5 p.u. Izero = j 1.153 p.u. The fault is

What is the posit ive sequence currents in a three phase system, when the original phasors at which are Ia = (12 + j6), Ib = (12 j 12), Ic = ( 15 + j10) ?

A two-phase load draws the following phase currents: i1 (t) = Im sin( t 1 ), i2 (t) = Im cos( t 2). These currents are balanced if 1 is equal to

The sequence components of the fault current are as follows: Ipositive = j1.5 pu, I negative = j0.5 pu, Izero = j1 pu. The type of fault in the system is

What is the utilization factor of a power station which supplies the following loads ? Load A: Motor load of 200 kW between 10 AM to 7 PM Load B: Lighting load of 100 k W bet ween 7 PM to 11 PM Load C: Pumping load of 110 kW between 3 PM to 10 AM

For a power system network with n nodes, Z33 of its bus impedance matrix is j0.5 per unit. The voltage at node 3 is 1.3 10 per unit. If a capacitor having reactance of j3.5 per unit is now added to the network between node 3 and the reference node, the current drawn by the capacitor per unit is

Base load power plants are P wind farms Q run-of-river plants R nuclear power plants S diesel power plants

A single circuit 50 Hz, 3 transmission line has the following parameters per km. R = 0.2 , L = 1.3 mH, C = 0.01 F The efficiency of the line, if the line is 120 km long and deliver 40 mW at 132 kV and 0.8 pf lagging will be _________%

Buses for load flow studies are classified as (i) the load bus (ii) the generator bus (iii) the slace bus The correct combination of the pair of quantities specified having their usual meaning for different buses is Load Bus Generator Slace bus

Out of the following plant categories (i) Nuclear (ii) Run-of-river (iii) Pump Storage (iv) Diesel the base load power plants are

Three generators are feeding a load of 100 MW. The details of the generators are given below. RatingEfficiencyRegulation(MW)(%)(p.u) on 100 MVA baseGenerator-1100200.02Generator-2100300.04Generator-3100400.03In the event of increased load power demand, which of the following will happen?

The total reactance and total susceptance of a lossless overhead EHV line, operating at 50 Hz, are given by 0.045 pu and 1.2 pu respectively. If the velocity of wave propagation is 3 105 km/s, then approximate length of the line is

The A, B, C, D constants of a 220 kV line are: A = D = 0.94 1 , B = 130 73 , C = 0.001 90 If sending end voltage of the line for a given load delivered at nominal voltage is 240 kV, then % voltage regulation of the line is

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

Shunt reactors are sometimes used in high voltage transmission systems to

The fuel cost functions of two powr plants are

A single-phase load is supplied by a single-phase volt age source. If the current flowing from the load to the source is 10 150 A and if the voltage at the load terminals is 100 60 V, then the

Power consumed by a balanced 3-phase, 3-wire load is measured by the two wattmeter method. The first wattmeter reads twice that of the second. Then the load impedance angle in radians is

A 3-bus power system network consists of 3 transmission lines. The bus admittance matrix of the uncompensated system is

A generating station has a maximum demand of 50 MW, a load factor of 60%, a plant capacity factor of 45% and if the plant while running as per schedule, were fully loaded. The daily energy produced will be ________ MW

For a power system network with n nodes, Z

Base load power plants are

If the sheath resistance is 2.14 /km and that of the conduct or is 0.1625 /k m, and mutual inductance of the shealth is 3.13 10

The insulation resistance of a cable of length 10 km is 1 M . For a length of 100 km of the same cable, the insulation resistance will be _______M

The per unit impedance of a 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 __________

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 Megawatts, would be _________

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. The consumpt ion of energy in kWh is______

In a high voltage dc transmission scheme, reactive power is needed both for rectifier at the sendingend and, for inverter at the receiving-end. During the operation of such a dc link, rectifier receives

The main consideration for higher and higher operating voltage of transmission is to

Bulk power transmission over long HVDC lines are preferred, on account of

The transient stability of the power system can be effectively improved by

The sequence components of the fault current are as follows: I

Determine the correctness or otherwise of the following Assertion [a] and the Reason [r]. Assertion: Fast decoupled load flow method gives approximate load flow solution because it uses several assumptions.
Reason: Accuracy depends on the power mismatch vector tolerance.

If a 75 MVA, 10 kV synchronous generator has X_d = 0.4 p.u, then X_d value (in p.u.) to a base of 100 MVA, 11 kV is ___________

A cable has following characteristics:
L = 0.201 H/m and C = 196.2 p/F/m.
The velocity of wave propagation through the cable is ________ m/s

A three phase 50 Hz line consists of three conductors each of diameter 21 mm. The spacing between the conductors as follows: A B = 3m, B C = 5m, C A = 3.6 m
If the line operates at 132 kV, the reactive voltampere generatd by the line per km is _______kVAr

If the sheath resistance is 2.14 /km and that of the conduct or is 0.1625 /k m, and mutual inductance of the shealth is 3.13 10⁷ H/m. When the cable is 2 km long and supply is 50 Hz, the ratio of sheath loss to core loss of the cable will be_______

A single line to ground fault occurs on an unloaded generator in phase a. If x_d = x₂ = 0.25 p.u., x₀ = 0.15 p.u., reactance connected in the neutral, x_n = 0.05 p.u. and the initial prefault voltage is 1.0 p.u., then the magnitude of the fault current will be ________ p.u.

A source v_s (t) =V cos 100 t has an internal impedance of (4 + j3) If a purely resistive load connected to this source has to extract the maximum power out of the source, its value in should be

The following data pertain to two alternators working in parallel and supplying a total load of 80 MW:
Machine 1: 40 MVA with 5% speed regulation
Machine 2: 60 MVA with 5% speed regulation
The load sharing between machines 1 and 2 will be

A fault occuring at the terminals of an unloaded synchronous generator opetaing at its rated voltage has resulted in the following values of the current and voltage.
I_a0 = j 2.37 p.u.
I_a1 = j 3.05 p.u.
I_a2 = j 0.68 p.u.
V_a0 = V_a1 = V_a2 = j 2.37 p.u.
The fault that has occurred is

The following sequence currents were recorded in a power system under a fault condition:
I_positive = j 1.653 p.u.
I_negative = j 0.5 p.u.
I_zero = j 1.153 p.u.
The fault is

What is the posit ive sequence currents in a three phase system, when the original phasors at which are I_a = (12 + j6), I_b = (12 j 12), I_c = ( 15 + j10) ?

A two-phase load draws the following phase currents: i₁ (t) = I_m sin( t ₁ ), i₂ (t) = I_m cos( t ₂). These currents are balanced if ₁ is equal to

The sequence components of the fault current are as follows: I_positive = j1.5 pu, I _negative = j0.5 pu, I_zero = j1 pu. The type of fault in the system is

What is the utilization factor of a power station which supplies the following loads ?
Load A: Motor load of 200 kW between 10 AM to 7 PM
Load B: Lighting load of 100 k W bet ween 7 PM to 11 PM
Load C: Pumping load of 110 kW between 3 PM to 10 AM

For a power system network with n nodes, Z₃₃ of its bus impedance matrix is j0.5 per unit. The voltage at node 3 is 1.3 10 per unit. If a capacitor having reactance of j3.5 per unit is now added to the network between node 3 and the reference node, the current drawn by the capacitor per unit is

Base load power plants are
P wind farms
Q run-of-river plants
R nuclear power plants
S diesel power plants

A single circuit 50 Hz, 3 transmission line has the following parameters per km.
R = 0.2 , L = 1.3 mH, C = 0.01 F
The efficiency of the line, if the line is 120 km long and deliver 40 mW at 132 kV and 0.8 pf lagging will be _________%

Buses for load flow studies are classified as (i) the load bus (ii) the generator bus (iii) the slace bus The correct combination of the pair of quantities specified having their usual meaning for different buses is
Load Bus Generator Slace bus

Out of the following plant categories
(i) Nuclear
(ii) Run-of-river
(iii) Pump Storage
(iv) Diesel the base load power plants are

The total reactance and total susceptance of a lossless overhead EHV line, operating at 50 Hz, are given by 0.045 pu and 1.2 pu respectively. If the velocity of wave propagation is 3 10⁵ km/s, then approximate length of the line is

The A, B, C, D constants of a 220 kV line are:
A = D = 0.94 1 ,
B = 130 73 ,
C = 0.001 90
If sending end voltage of the line for a given load delivered at nominal voltage is 240 kV, then % voltage regulation of the line is