## Power Systems MCQ Set 1

1. For an ac three-phase four wire system, having a voltage of 415V, with load of 120 kW and resistance of 0.05Ω at power factor of 0.75. The incurred copper losses of the system is ____

a) 4.955 kW

b) 47 kW

c) 49 kW

d) 7.9 kW

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2. The ratio of area of cross section of the wire of a 3-phase 3-wire and that of dc 2-wire mid point earthed system will be ___

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3. Distributors fed at both ends has an advantage of ____

a) continuous supply

b) fault isolation

c) being economical

d) all of the mentioned

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4. Why is a ring main distribution system preferred to a radial system?

1. Voltage drop in feed is more

2. Supply is reliable

3. Power factor is higher

a) 2

b) 1,2

c) 1,2,3

d) 2,3

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5. For a given power delivered, if the working voltage of a distribution line is decreased to ‘x’ times, the cross sectional area ‘a’ of distributor line would reduce to _____

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6. For a given power delivered, if the working voltage of a distribution line is increased to ‘x’ times, the cross sectional area ‘a’ of distributor line would reduce to _______

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7. The distribution feeding system of ring main system has ________

a) one feeder

b) 2 feeders

c) 4 feeders

d) cannot be said

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8. A substation records a dip in the voltage received by 15%. To overcome this issue, the booster employed at the substation is _____

a) a series wound generator coupled to dc shunt motor

b) a series wound motor

c) a shunt motor operating at lagging power factor

d) a shunt motor coupled to differential motor

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9. A substation records a dip in the voltage received by 15%. To overcome this issue, the booster employed at the substation which should have a _______

a) low voltage and high current generator

b) high voltage and low current generator

c) medium voltage but high current generator

d) any of the mentioned

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10. Single core cables for an ac systems are not provided with armouring.

a) True

b) False

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## Power Systems MCQ Set 2

1. A 10 MVA, 11 kV alternators has positive, negative and zero sequence reactance of 25%, 40%, 10% respectively. The resistance that must be placed in the neutral such that zero sequence of fault current for a single phase to ground fault will not exceed the rated line current in pu is ______

a) 0.22

b) 0.11

c) 0.16

d) 0.97

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2. A 10 MVA, 11 kV alternator has positive, negative and zero sequence reactance of 25%, 40%, 10% respectively. The resistance that must be placed in the neutral such that fault current for a single phase to ground fault will not exceed the rated line current in pu is _______

a) 0.97

b) 0.22

c) 0.87

d) 0.45

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3. A 10 MVA, 11 kV alternator has positive, negative and zero sequence reactance of 25%, 40%, 10% respectively. The resistance that must be placed in the neutral such that fault current for a single phase to ground fault will not exceed the rated line current in ohms is ____

a) 11.7

b) 12.8

c) 2.66

d) 5.2

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4. (I) Unsymmetrical spacing configurations cause the line interference.

(II) Unsymmetrical spacing causes the voltage induction in the communication lines.

a) (I) and (II) are valid

b) Only (I) is valid

c) Only (II) is valid

d) Both are invalid

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5. (I) Unsymmetrical spacing configurations cause the line interference.

(II) Unsymmetrical spacing causes the voltage induction in the communication lines.

The above problems can be eliminated by ________

a) transposition

b) parallel lines

c) three phase

d) all of the mentioned

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6.Transposition is the mean to balance ______

a) Inductance

b) Voltage

c) Current

d) All of the mentioned

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7. Over the length of one transposition cycle of a power line, the total flux linkages of a nearby telephone line are zero for the unbalanced three phase currents.

a) True

b) False

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8. Over the length of one transposition cycle of a power line, the total flux linkages of a nearby telephone line are zero for the balanced three phase currents.

a) The above statement is valid

b) The above statement is invalid

c) It can’t be concluded

d) The above statement is valid for all conditions.

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## Power Systems MCQ Set 3

1. If we account for the effect of the presence of the capacitance of the transmission line, then the capacitance _____

a) increases

b) decreases

c) remains same

d) increases hyperbolically

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2. While estimating the line parameters, the term self GMD is used for the calculation of ________

a) inductance

b) capacitance

c) conductance

d) inductance, capacitance and conductance

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3. The ground effect causes line capacitance to _______

a) Increase by 0.2%

b) Increase by 2%

c) Decrease by 0.2%

d) Decrease by 2%

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4. If the spacing between the phase conductors is increased, the line capacitance will ___

a) decrease

b) increase

c) remain same

d) depends on the conductor

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5. If the length of the transmission line is increased, the line charging current in the TL will _______

a) increase

b) decrease

c) remain same

d) not be affected

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6. On applying the alternating sine wave as the input to the line, the line capacitance draws _______

a) leading sinusoidal current

b) lagging sinusoidal current

c) current in phase with voltage

d) depends on the receiving end load

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7. The capacitance becomes significant for the ____

a) long transmission line

b) medium transmission line

c) short transmission line

d) cannot be determined

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8. The method of the images is applied to find the ______

a) calculation of capacitance

b) calculation of inductance

c) calculation of resistance

d) calculation of effect of the earth on capacitance

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## Power Systems MCQ Set 4

1. A single phase 50 hz, generator supplies an inductive load of 5 MW at a power factor of 0.8 lagging using OHTL over 20 km. The resistance and reactance are 0.39Ω and 3.96 Ω. The voltage at receiving station is maintained at 10 KV. The sending end voltage is 11.68 kV. The voltage regulation will be _______

a) 16.8 %

b) 18.8%

c) 21.75%

d) 12.8%

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2. A single phase 50 hz, generator supplies an inductive load of 5 MW at a power factor of 0.8 lagging using OHTL over 20 km. The resistance and reactance are 0.39Ω and 3.96 Ω. The voltage at receiving station is maintained at 10 KV. Identify the transmission line and the voltage regulation.

a) STL, 11.68%

b) MTL, 11.68

c) STL, 21.5%

d) MTL, 14.2%

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_{s}= |V

_{r}|+|I|*(RcosФ

_{r}+ XsinФ

_{r}) = 10000+625(0.39*0.8+3.96*0.6) = 11.68kV VR = (11.68-10)*100/10 = 16.8 %.

3. A single phase 50 hz, generator supplies an inductive load of 5 MW at a power factor of 0.8 lagging using OHTL over 20 km. The resistance and reactance are 0.39Ω and 3.96 Ω. The voltage at receiving station is maintained at 10 KV. The sending end voltage is 11.68 kV. The half the voltage regulation will be _______

a) 8.4 %

b) 16.8 %

c) 14.2%

d) 10.5%

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4. A single phase 50 hz, generator supplies an inductive load of 5 MW at a power factor of 0.8 lagging using OHTL over 20 km. The resistance and reactance are 0.39Ω and 3.96 Ω. The voltage at receiving station is maintained at 10 KV. The sending end voltage is 11.68 kV. The new sending end voltage at the half the voltage regulation is _______

a) 10.84 kV

b) 11.84 kV

c) 8.84 kV

d) 16.2 kV

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5. A single phase 50 hz, generator supplies an inductive load of 5 MW at a power factor of 0.8 lagging using OHTL over 20 km. The resistance and reactance are 0.39Ω and 3.96 Ω. The voltage at receiving station is maintained at 10 KV. The sending end voltage is 11.68 kV. If the voltage regulation is reduced to 50%, then the power factor at this operation mode will be _____

a) 0.95

b) 0.92

c) 0.74

d) 0.90

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_{r}+ XsinФ

_{r}) …(1) I = 5000/(cosФ

_{r}*10) …(2) Solving above eqaution Ф

_{r}= 18.04° Cos Ф

_{r}= 0.9508, lagging.

6. A single phase 50 hz, generator supplies an inductive load of 5 MW at a power factor of 0.8 lagging using OHTL over 20 km. The resistance and reactance are 0.39Ω and 3.96 Ω. The voltage at receiving station is maintained at 10 KV. The sending end voltage is 11.68 kV. If the voltage regulation is reduced to 50%, then the power factor angle at this operation mode will be _______

a) 18.04°

b) 8.04°

c) 21.06°

d) 12°

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_{r}+ XsinФ

_{r}) …(1) I = 5000/(cosФ

_{r}*10) …(2) Solving above equation Ф

_{r}= 18.04°.

7. A single phase 50 hz, generator supplies an inductive load of 5 MW at a power factor of 0.8 lagging using OHTL over 20 km. The resistance and reactance are 0.39Ω and 3.96 Ω. The voltage at receiving station is maintained at 10 KV. The sending end voltage is 11.68 kV. If the voltage regulation is reduced to 50%, then the power factor at this operation mode will be ______

a) 0.95, lagging

b) 0.92, leading

c) 0.95, lagging

d) 0.90, leading

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_{r}+ XsinФ

_{r}) …(1) I = 5000/(cosФ

_{r}*10) …(2) Solving above equation Ф

_{r}= 18.04° Cos Ф

_{r}= 0.9508, lagging.

8. A single phase 50 hz, generator supplies an inductive load of 5 MW at a power factor of 0.8 lagging using OHTL over 20 km. The resistance and reactance are 0.39Ω and 3.96 Ω. The voltage at receiving station is maintained at 10 KV. The sending end voltage is 11.68 kV. If the voltage regulation is reduced to 50%, then the power factor angle at this operation mode will be ________

a) 18.04°, lagging

b) 18.04°, leading

c) 21.06°, leading

d) 21.06°, lagging

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_{r}+ XsinФ

_{r}) …(1) I = 5000/(cosФ

_{r}*10) …(2) Solving above equation Ф

_{r}= 18.04°, lagging.

9. A single phase 50 hz, generator supplies an inductive load of 5 MW at a power factor of 0.8 lagging using OHTL over 20 km. The resistance and reactance are 0.39Ω and 3.96 Ω. The voltage at receiving station is maintained at 10 KV. The sending end voltage is 11.68 kV. If the voltage regulation is reduced to 50%, then the receiving end current at this operation mode will be _______

a) 526 A

b) 549 A

c) 521 A

d) 580 A

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_{r}+ XsinФ

_{r}) …(1) I = 5000/(cosФ

_{r}*10) …(2) Solving above equation Ф

_{r}= 18.04°, lagging I = 526 A.

10. Suppose the transmission line is loaded with its surge impedance, the receiving-end voltage is greater than sending end voltage.

a) True

b) False

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## Power Systems MCQ Set 5

1. What is the value of charging current in short transmission lines?

a) Less than medium transmission lines

b) Equal to medium transmission lines

c) More than medium transmission lines

d) More than long transmission lines

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2. What is the value of Inductive reactance in short transmission lines?

a) More at reciving end

b) More at sending end

c) Uniformly distributed over entire length

d) More in middle of sending end and reciving end

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3. Regulation of short transmission lines depends:

a) Only on line resistance

b) Only on line inductance

c) Only on line capacitance

d) On line inductance and line resistance

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4. What is the percentage voltage regulation of short transmission line if its sending end and reciving end voltages are 160 KV and 132 KV respectively?

a) 30 %

b) 21.21 %

c) 12.12 %

d) 38.22 %

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5. A single phase transmission line is transmitting 1,100 KW power at 11 KV and at unity power fector. If it has a total resistance of 5 Ω, what is the efficiency of the transmission line?

a) 80 %

b) 89.65 %

c) 97.24 %

d) 99.54 %

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6. Voltage regulation of a transmission line should be ________

a) Minimum

b) Maximum

c) Greater than 50 %

d) Less than 50 %

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7. Which of the following is like equivalent circuit of short transmission line?

a) Series RLC circuit

b) Parallel RLC circuit

c) Series RL circuit

d) Parallel RL circuit

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8. In single phase transmission lines resistance and inductance are considered only up to neutral.

a) True

b) False