Series capacitive compensation on EHV transmission lines is used to

improve the stability of the system

improve the protection of the line

In load flow analysis, the load connected at a bus is represented as

constant current drawn from the bus

constant impedance connected at the bus

voltage and frequency dependent source at the bus

constant real and reactive drawn from the bus

If the reference bus is changed in two load flow runs with same system data and power obtained for reference bur taken as specified P and Q in the latter run

the system losses will be changed but complex bus voltages remain unchanged

the system losses will be unchanged but complex bus voltage will change

the system losses will be changed but complex bus voltages remain unchanged

the system losses as well be as complex bus voltage will change

the system losses as well be as complex bus voltage will unchanged

A lossless radial transmission line with surge impedance loading

takes positive VAr at sending end and zero VAr at receiving end

takes negative VAr at sending end and zero VAr at receiving end

takes positive VAr at sending end and zero VAr at receiving end

has flat voltage profile and unity power factor at all points along it

has sending end voltage higher than receiving end voltage and unity power factor at sending end

Bundled conductors are employed to

increase the short circuit current

reduce the short circuit current

increase the short circuit current

Critical voltage limit of a transmission line is increased by

increasing the spacing between conductors

increasing the radius of the conductors

increasing the spacing between conductors

reducing the spacing between conductors

reducing the radius of the conductors

For effective use of a counterpoise wire

its leakage resistance should be equal to the surge impedance

its leakage resistance should be greater than the surge impedance

its leakage resistance should be less than the surge impedance

its leakage resistance should be equal to the surge impedance

two resistance may have any relation

For the same voltage boost, the reactive power capacity is

it is same for both series and shunt

If is the loss angle of the cable, then its power factor is

depends upon but it is not as per (a) and (b)

When a d.c source is switched is purely inductive, the current response is

a straight line off-set from the origin

an exponentially decaying curve

a straight line passing through the origin

a straight line off-set from the origin

In the optimum generator scheduling of different power plants, the minimum fuel cost is obtained when

only the incremental fuel cost oif each plant is the same

the penalty factor of each plant is the same

the ratio of the incremental fuel cost to the penalty factoir of each plant is the same

the incremental fuel cost of each pl ant multiplied by its penalty factor is the same

For an unbalanced fault, with paths for zero sequence currents, at the point of fault

negative sequence voltage is minimum and zero sequence voltage is maximum

negative and zero sequence voltages are minimum

negative and zero sequence voltages are miximum

negative sequence voltage is minimum and zero sequence voltage is maximum

negative sequence voltage is maximum and voltage is minimum

An ideal voltage source is connected across a variable resistance. The variation of current as a function of resistance is given by

a straight line passing through the origin

With the help of a reactive compensator it is possible to have

constant voltage operation only

both constant voltage and unity p.f.

either constant voltage or unity p.f.

The voltage of generator and an infinite bus are given as 0.92 10 and 1.0 0 respectively. The generator acts as a

the data is insufficient to judge

In a power station, the cost of generation of power reduces most effectively when

diversity factor alone increase

both diversity factor and load factor increases

both diversity factor and load factor decreases

A 50 Hz balanced three-phase, Y-connected supply is connected to a bal anced three-phase Y-connected load. If the instantaneous phase -a of the supply voltage is Vcos ( t) and the phase-a of the load current is Icos ( t ), the instantaueous three-phase power is

time-varying with an aver age value of (3/2)VI cos and a frequency of 100 Hz.

a constant with a magnitude of VI cos

a constant with a magnitude of (3/2)VI cos

time-varying with an aver age value of (3/2)VI cos and a frequency of 100 Hz.

time-varying with an average value of VIcos and a frequency of 50 Hz.

249 + Mcqs in Power systems miscellaneous in Power Systems Page 4 McqOptions

151.	A conductor is composed of seven identical copper strands, each having a radius r. The self GMD of the conductors will be
A.	2.177 r
B.	2.645 r
C.	2.141 r
D.	1.21 r
Answer» B. 2.645 r

Discussion

152.	The leakage resistance of a 50 km long cable is 1 M . For a 100 km long cable it will be
A.	1 M
B.	2 M
C.	0 5 M
D.	none of these
Answer» E.

Discussion

153.	If r is radius of the conductor and R is radius of the sheath of strength, then
A.	r /R > 1 0
B.	r /R > 1 0
C.	r/R < 0 632
D.	r/R < 0 368
Answer» E.

Discussion

154.	Series capacitive compensation on EHV transmission lines is used to
A.	reduce the line loading
B.	improve the stability of the system
C.	reduce the voltage profile
D.	improve the protection of the line
Answer» E.

Discussion

155.	A 3 , 50 Hz, 132 kV transmission line consists of conduct or of 1.17 cm diameter and spaced equilaterely at a distance of 3m. The line conductors have smooth surface with value for m = 0.96. The barometric pressure is 72 cm of Hg and temperature of 20 C. The corona loss in foul weather condition will be
A.	3.12 kW/km/phase
B.	4.84 kW/km/phase
C.	8.70 kW/km/phase
D.	none of these
Answer» B. 4.84 kW/km/phase

Discussion

156.	For a load flow solution, the quantities normally specified at a voltage controlled bus are
A.	P and Q
B.	P and \|V\|
C.	Q and \|V\|
D.	P and
Answer» E.

Discussion

157.	In load flow analysis, the load connected at a bus is represented as
A.	constant current drawn from the bus
B.	constant impedance connected at the bus
C.	voltage and frequency dependent source at the bus
D.	constant real and reactive drawn from the bus
Answer» E.

Discussion

158.	What is the corona loss of a 3 line, 160 km long, conductor diameter 1.036 cm, 2.44 delta spacing, air temperature 26 , corresponding to a barometric pressure of 72 cm, operating voltage 110 kV at 50 Hz. m = 0.78?
A.	322 kW
B.	792 kW
C.	800 kW
D.	841 kW
Answer» E.

Discussion

159.	What is the charging kVAr taken by a 10 km length of the cable when connected to an 11 kV, 50 Hz supply? The capacitance measured between any two cores of a three phase belted cable is 0.5 F/km.
A.	380 kVAr
B.	150 kVAr
C.	114 kVAr
D.	400 kVAr
Answer» B. 150 kVAr

Discussion

160.	If the reference bus is changed in two load flow runs with same system data and power obtained for reference bur taken as specified P and Q in the latter run
A.	the system losses will be unchanged but complex bus voltage will change
B.	the system losses will be changed but complex bus voltages remain unchanged
C.	the system losses as well be as complex bus voltage will change
D.	the system losses as well be as complex bus voltage will unchanged
Answer» B. the system losses will be changed but complex bus voltages remain unchanged

Discussion

161.	If corona loss on a particular system at 50 Hz is 1 kW/phase per km, then corona loss on the same system with supply frequency 25 Hz will be
A.	1 kW/phase/km
B.	0 5 kW/phase/km
C.	0 667 kW/phase/km
D.	none of these
Answer» D. none of these

Discussion

162.	A 1 km of a three phase metal sheathed belted cable gave a measured capacitance of 0.7 F bet ween one conduct or and the other two conductors bunched together with the earth sheath and 1.5 F measured between the three bunched conductors and the sheath. What is the charging current, when the cable is connected at 11 kV, 50 Hz supply?
A.	0.80 A/phase
B.	1.40 A/phase
C.	1.59 A/phase
D.	1.695 A/phase
Answer» D. 1.695 A/phase

Discussion

163.	Where voltage are high and current to be interrupted is low, the breaker preferred is
A.	air blast C.B
B.	oil C.B.
C.	vaccum C.B.
D.	any of these
Answer» D. any of these

Discussion

164.	A 1 load of 200 kVA is delivered at 2500 V over a transmission line having R = 1.4 , X = 0.8 . What is the power at the sending end when the power factor of the load is 0.8 leading?
A.	0.8 leading
B.	0.82 (leading)
C.	0.82 (lagging)
D.	0.6 (lagging)
Answer» C. 0.82 (lagging)

Discussion

165.	The X:R ratio of 220 kV line as compared to 400 kV line is
A.	greater
B.	smaller
C.	equal
D.	it could be anything
Answer» C. equal

Discussion

166.	A lossless radial transmission line with surge impedance loading
A.	takes negative VAr at sending end and zero VAr at receiving end
B.	takes positive VAr at sending end and zero VAr at receiving end
C.	has flat voltage profile and unity power factor at all points along it
D.	has sending end voltage higher than receiving end voltage and unity power factor at sending end
Answer» B. takes positive VAr at sending end and zero VAr at receiving end

Discussion

167.	Bundled conductors are employed to
A.	reduce the short circuit current
B.	improve system stability
C.	decreases system stability
D.	increase the short circuit current
Answer» D. increase the short circuit current

Discussion

168.	An RLC series circuit remains predominantly inductive
A.	at resonance frequency
B.	below resonance frequency
C.	above resonance frequency
D.	at lower half power frequency
Answer» D. at lower half power frequency

Discussion

169.	Critical voltage limit of a transmission line is increased by
A.	increasing the radius of the conductors
B.	increasing the spacing between conductors
C.	reducing the spacing between conductors
D.	reducing the radius of the conductors
Answer» B. increasing the spacing between conductors

Discussion

170.	For effective use of a counterpoise wire
A.	its leakage resistance should be greater than the surge impedance
B.	its leakage resistance should be less than the surge impedance
C.	its leakage resistance should be equal to the surge impedance
D.	two resistance may have any relation
Answer» C. its leakage resistance should be equal to the surge impedance

Discussion

171.	For the same voltage boost, the reactive power capacity is
A.	more for shunt capacitor
B.	more for series capacitor
C.	it is same for both series and shunt
D.	uncertain
Answer» B. more for series capacitor

Discussion

172.	If is the loss angle of the cable, then its power factor is
A.	sin
B.	cos
C.	independent of
D.	depends upon but it is not as per (a) and (b)
Answer» B. cos

Discussion

173.	The transmission line feeding power on either side of the main transmission line is called
A.	Secondary distribution
B.	Secondary transmission
C.	Primary transmission
D.	Primary distribution
Answer» C. Primary transmission

Discussion

174.	Three insulating materials with same maximum working stress and permittivities 2 5, 3 0, 4 0, are used in a single core cable, then location of the materials with respect to the core of the cable will be
A.	2 5, 3 0, 4 0
B.	3 0, 2 5, 4 0
C.	4 0, 3 0, 2 5
D.	4 0, 2 5, 3 0
Answer» D. 4 0, 2 5, 3 0

Discussion

175.	The single phase line of 230 V and 3 phase line of 400 V which feed different domestic circuits and industrial loads represent
A.	primary distribution
B.	secondary distribution
C.	secondary transmission
D.	none of these
Answer» C. secondary transmission

Discussion

176.	If an induction machine is run at above synchromous speed, it acts as
A.	a synchronous motor
B.	an indcution generator
C.	an inductor motor
D.	none of these
Answer» C. an inductor motor

Discussion

177.	The main criterion for selection of the size of a distribution for a radial distribution system is
A.	voltage drop
B.	corona loss
C.	temperature rise
D.	capital cost
Answer» B. corona loss

Discussion

178.	When a d.c source is switched is purely inductive, the current response is
A.	an exponentially rising curve
B.	an exponentially decaying curve
C.	a straight line passing through the origin
D.	a straight line off-set from the origin
Answer» D. a straight line off-set from the origin

Discussion

179.	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.
A.	L L fault
B.	L L G fault
C.	L G fault
D.	none of these
Answer» C. L G fault

Discussion

180.	In the optimum generator scheduling of different power plants, the minimum fuel cost is obtained when
A.	only the incremental fuel cost oif each plant is the same
B.	the penalty factor of each plant is the same
C.	the ratio of the incremental fuel cost to the penalty factoir of each plant is the same
D.	the incremental fuel cost of each pl ant multiplied by its penalty factor is the same
Answer» E.

Discussion

181.	Xd, X 'd and X "d are steady stated-axis synchronous reactances, transient d-axis reactance and sub-transient d-reactance of a synchronous machine respectively. Which of the following statement is true?
A.	Xd > X'd > X"d
B.	X"d > X'd > Xd
C.	X'd > X"d > Xd
D.	Xd > X"d > X'd
Answer» B. X"d > X'd > Xd

Discussion

182.	For a fault at the terminals of a synchronous generator, the fault current is maximum for a
A.	3-phase fault
B.	3-phase to ground fault
C.	line-to ground fault
D.	line-to-line fault
Answer» D. line-to-line fault

Discussion

183.	For an unbalanced fault, with paths for zero sequence currents, at the point of fault
A.	negative and zero sequence voltages are minimum
B.	negative and zero sequence voltages are miximum
C.	negative sequence voltage is minimum and zero sequence voltage is maximum
D.	negative sequence voltage is maximum and voltage is minimum
Answer» C. negative sequence voltage is minimum and zero sequence voltage is maximum

Discussion

184.	50 Hz generator is delivering 50% of the power that is capable of delivering through a transmission line to an infinite bus. A fault occurs that increases the reactance between the generator and bus to 500% before the fault. When the fault is isolated, the maximum power that can be delivered is 75% of the original maximum value. The critical clearing angle for the condition is desired, will be
A.	67.44
B.	70
C.	50.4
D.	none of these
Answer» B. 70

Discussion

185.	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
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

186.	An ideal voltage source is connected across a variable resistance. The variation of current as a function of resistance is given by
A.	a straight line passing through the origin
B.	a ractangular hyperbola
C.	a parabola
D.	all of the above
Answer» C. a parabola

Discussion

187.	In a synchronous machine, in case the axis of field flux is in line with the armature flux, the machine is working
A.	as synchronous moter
B.	as synchronous generator
C.	as floating machine
D.	the machine will not work
Answer» D. the machine will not work

Discussion

188.	A power system network consists of three elements 0 - 1, 1 - 2 and 2 - 0 of per unit impedance 0.2, 0.4 respectively. Its bus impedance matrix is given by
A.	<table><tr><td></td><td></td><td>1</td><td></td><td>2</td></tr><tr><td>1</td><td rowspan="2"><img src="https://www.indiabix.com/_files/images/data-interpretation/common/15-sym-obracket-h1.gif"></td><td>7.5</td><td> </td><td>-2.5</td><td rowspan="2"><img src="https://www.indiabix.com/_files/images/data-interpretation/common/15-sym-cbracket-h1.gif"></td></tr><tr><td>2</td><td>-2.5</td><td> </td><td>5.0</td></tr></table>
B.	<table><tr><td></td><td></td><td>1</td><td></td><td>2</td></tr><tr><td>1</td><td rowspan="2"><img src="https://www.indiabix.com/_files/images/data-interpretation/common/15-sym-obracket-h1.gif"></td><td>0.16</td><td> </td><td>0.08</td><td rowspan="2"><img src="https://www.indiabix.com/_files/images/data-interpretation/common/15-sym-cbracket-h1.gif"></td></tr><tr><td>2</td><td>0.08</td><td> </td><td>0.24</td></tr></table>
C.	<table><tr><td></td><td></td><td>1</td><td></td><td>2</td></tr><tr><td>1</td><td rowspan="2"><img src="https://www.indiabix.com/_files/images/data-interpretation/common/15-sym-obracket-h1.gif"></td><td>0.16</td><td> </td><td>-0.08</td><td rowspan="2"><img src="https://www.indiabix.com/_files/images/data-interpretation/common/15-sym-cbracket-h1.gif"></td></tr><tr><td>2</td><td>-0.08</td><td> </td><td>0.24</td></tr></table>
D.	<table><tr><td></td><td></td><td>1</td><td></td><td>2</td></tr><tr><td>1</td><td rowspan="2"><img src="https://www.indiabix.com/_files/images/data-interpretation/common/15-sym-obracket-h1.gif"></td><td>0.6</td><td> </td><td>0.4</td><td rowspan="2"><img src="https://www.indiabix.com/_files/images/data-interpretation/common/15-sym-cbracket-h1.gif"></td></tr><tr><td>2</td><td>0.4</td><td> </td><td>0.8</td></tr></table>
Answer» C. <table><tr><td></td><td></td><td>1</td><td></td><td>2</td></tr><tr><td>1</td><td rowspan="2"><img src="https://www.indiabix.com/_files/images/data-interpretation/common/15-sym-obracket-h1.gif"></td><td>0.16</td><td> </td><td>-0.08</td><td rowspan="2"><img src="https://www.indiabix.com/_files/images/data-interpretation/common/15-sym-cbracket-h1.gif"></td></tr><tr><td>2</td><td>-0.08</td><td> </td><td>0.24</td></tr></table>

Discussion

189.	With the help of a reactive compensator it is possible to have
A.	constant voltage operation only
B.	unity p.f. operation only
C.	both constant voltage and unity p.f.
D.	either constant voltage or unity p.f.
Answer» E.

Discussion

190.	The voltage of generator and an infinite bus are given as 0.92 10 and 1.0 0 respectively. The generator acts as a
A.	shunt coil
B.	shunt capacitor
C.	the data is insufficient to judge
D.	none of these
Answer» B. shunt capacitor

Discussion

191.	In a power station, the cost of generation of power reduces most effectively when
A.	diversity factor alone increase
B.	both diversity factor and load factor increases
C.	load factor alone increases
D.	both diversity factor and load factor decreases
Answer» E.

Discussion

192.	Load frequency control is achieved by properly matching the individual machine s
A.	reactive powers
B.	generated voltages
C.	turbine inputs
D.	turbine and generator ratings
Answer» D. turbine and generator ratings

Discussion

193.	The combined frequency regulation of machines in area of capacity 1500 MW and operating at a normal frequency of 60 kHz is 0.1 puonits own base capacity. The regulation in Hz/ MW will be
A.	0.1/1500
B.	60/1500
C.	6/1500
D.	60/150
Answer» D. 60/150

Discussion

194.	A 50 Hz balanced three-phase, Y-connected supply is connected to a bal anced three-phase Y-connected load. If the instantaneous phase -a of the supply voltage is Vcos ( t) and the phase-a of the load current is Icos ( t ), the instantaueous three-phase power is
A.	a constant with a magnitude of VI cos
B.	a constant with a magnitude of (3/2)VI cos
C.	time-varying with an aver age value of (3/2)VI cos and a frequency of 100 Hz.
D.	time-varying with an average value of VIcos and a frequency of 50 Hz.
Answer» C. time-varying with an aver age value of (3/2)VI cos and a frequency of 100 Hz.

Discussion

195.	An industrial consumer has a connected load of 100 k W. The maximum demand is 80 k W. On an average each machine works for 8 hours a day for 300 working days in a year. If tariff is (5000) + 800 per kW of maximum demand + 1.15 per kWh of energy consumed, the annual bill of the consumer will be
A.	350000
B.	400,000
C.	250,000
D.	34500
Answer» E.

Discussion

196.	A synchronous generator connected to infinite bus delivers power at a log p.f. If its excitation is increased
A.	the terminal voltage increases
B.	voltage angle increases
C.	current deliverted increased
D.	both (b) and (c)
Answer» E.

Discussion

197.	A 100 kVA transformer has 4% impedance and 50 kVA transformer has 3% impedance when they are operated in parallel, which transformer will reach full load first
A.	3%
B.	4%
C.	data is insufficient
D.	none of these
Answer» B. 4%

Discussion

198.	The following data pertain to two alternators working in parallel and supplying a total load of 80 MW:
A.
B.	<table><tr><td style="border-bottom:1px solid #000000;vertical-align:bottom;padding-bottom:2px;"><center>P<sub>1</sub></center></td><td rowspan="2"> = </td><td style="border-bottom:1px solid #000000;vertical-align:bottom;padding-bottom:2px;"><center>P<sub>2</sub></center></td></tr><tr><td style="text-align: center;">48 MW</td><td style="text-align: center;">48 MW</td></tr></table>
C.	40 MW 40 MW
D.	30 MW 50 MW
E.	32 MW 48 MW
Answer» D. 30 MW 50 MW

Discussion

199.	What is the percentage increase of busbar voltage required to compensate for the reactance drop, when the feeder having a reactance of 5% carries a full load current at a p.f. 0.8 lagging?
A.	5%
B.	1.2%
C.	1.8%
D.	3%
Answer» E.

Discussion

200.	What is the posit ive sequence currents in a three phase system, when the original phasors at which are I
A.	14.8 Amp.
B.	16.2 Amp.
C.	18 Amp.
D.	10.2 Amp
Answer» B. 16.2 Amp.

Discussion

Explore topic-wise MCQs in Power Systems.

A conductor is composed of seven identical copper strands, each having a radius r. The self GMD of the conductors will be

The leakage resistance of a 50 km long cable is 1 M . For a 100 km long cable it will be

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Series capacitive compensation on EHV transmission lines is used to

For a load flow solution, the quantities normally specified at a voltage controlled bus are

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What is the corona loss of a 3 line, 160 km long, conductor diameter 1.036 cm, 2.44 delta spacing, air temperature 26 , corresponding to a barometric pressure of 72 cm, operating voltage 110 kV at 50 Hz. m = 0.78?

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In the optimum generator scheduling of different power plants, the minimum fuel cost is obtained when

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For an unbalanced fault, with paths for zero sequence currents, at the point of fault

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An ideal voltage source is connected across a variable resistance. The variation of current as a function of resistance is given by

In a synchronous machine, in case the axis of field flux is in line with the armature flux, the machine is working

A power system network consists of three elements 0 - 1, 1 - 2 and 2 - 0 of per unit impedance 0.2, 0.4 respectively. Its bus impedance matrix is given by

With the help of a reactive compensator it is possible to have

The voltage of generator and an infinite bus are given as 0.92 10 and 1.0 0 respectively. The generator acts as a

In a power station, the cost of generation of power reduces most effectively when

Load frequency control is achieved by properly matching the individual machine s

The combined frequency regulation of machines in area of capacity 1500 MW and operating at a normal frequency of 60 kHz is 0.1 puonits own base capacity. The regulation in Hz/ MW will be

A 50 Hz balanced three-phase, Y-connected supply is connected to a bal anced three-phase Y-connected load. If the instantaneous phase -a of the supply voltage is Vcos ( t) and the phase-a of the load current is Icos ( t ), the instantaueous three-phase power is

An industrial consumer has a connected load of 100 k W. The maximum demand is 80 k W. On an average each machine works for 8 hours a day for 300 working days in a year. If tariff is (5000) + 800 per kW of maximum demand + 1.15 per kWh of energy consumed, the annual bill of the consumer will be

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The following data pertain to two alternators working in parallel and supplying a total load of 80 MW:

What is the percentage increase of busbar voltage required to compensate for the reactance drop, when the feeder having a reactance of 5% carries a full load current at a p.f. 0.8 lagging?

What is the posit ive sequence currents in a three phase system, when the original phasors at which are I