1) What is the per unit system (PU)?
a. A ratio of actual value in any units to the base or reference value in the same units
b. A ratio of the base or reference value in any units to the actual value in the same units.
c. Ratio of the square of the actual value in any units to the square of base or the reference value in the same units
d. All of these
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Answer
Explanation
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ANSWER: A ratio of actual value in any units to the base or reference value in the same units
Explanation:
No explanation is available for this question!
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2) What is the simplified diagram called, after omitting all resistances, static loads, capacitance of the transmission lines and magnetising circuit of the transformer?
a. Single line diagram
b. Resistance diagram
c. Reactance diagram
d. Both (a) and (b)
e. None of these
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3) Which among these is the equivalent circuit for the synchronous motor?
a. Only a
b. Only b
c. Only c
d. Only d
e. None of these
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4) What will be the per unit impedance of a synchronous motor having a rating of 100 kVA, 13.2 kV and having a reactance of 75 Ω / ph?
a. 0.043 pu
b. 0.057 pu
c. 0.036 pu
d. 0.298 pu
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5) Which among these is the major advantage of per unit computations?
a. Per unit impedance of transformers is the same referred to either side of it.
b. For simulating steady state and transient models in the computer this method is very useful.
c. Manufactures usually specify the impedance of an apparatus in per unit system.
d. All of these
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6) What is the per unit impedance Z(Pu) in a three phase system?
a. ( Z * (MVA)B) / (KV)2
b. ( 1000 * (KV)B) / √3 IB
c. ( Z * (KV)2 ) / (MVA)B
d. None of these
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7) What is infinite bus in power system?
a. A large system with infinite voltage
b. A large system in which the voltage and frequency varies
c. A large system whose voltage and frequency remains constant throughout.
d. Both (a) and (b)
e. None of these
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Answer
Explanation
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ANSWER: A large system whose voltage and frequency remains constant throughout.
Explanation:
No explanation is available for this question!
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8) What is the formula to calculate the (kV)B on the HT section?
a. (kV)B on HT section * (HT voltage rating) / (LT voltage rating)
b. (kV)B on LT section * (HT voltage rating) / (LT voltage rating)
c. (kV)B on HT section * (LT voltage rating) / (HT voltage rating)
d. (kV)B on LT section * (LT voltage rating) / (HT voltage rating)
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Answer
Explanation
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ANSWER: (kV)B on LT section * (HT voltage rating) / (LT voltage rating)
Explanation:
No explanation is available for this question!
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9) What is the formula to calculate the (kV)B on the LT section?
a. (kV)B on HT section * (HT voltage rating) / (LT voltage rating)
b. (kV)B on LT section * (HT voltage rating) / (LT voltage rating)
c. (kV)B on HT section * (LT voltage rating) / (HT voltage rating)
d. (kV)B on LT section * (LT voltage rating) / (HT voltage rating)
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Answer
Explanation
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ANSWER: (kV)B on HT section * (LT voltage rating) / (HT voltage rating)
Explanation:
No explanation is available for this question!
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10) Which among the following assumptions are made in the reactance diagram?
a. The neutral reactance are neglected
b. Static loads are neglected.
c. The capacitance of the transmission lines are neglected
d. Only a and c
e. All of these
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11) Which of the following fault results into a three phase faults?
a. Single line to ground fault.
b. Double line to ground fault
c. Line to line fault
d. Fault due to all the three phases to earth.
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12) Which among these is the most commonly occurring fault?
a. Single line to ground fault.
b. Double line to ground fault
c. Line to line fault
d. Fault due to all the three phases to earth.
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13) In which portion of the transmission system is the occurrence of the fault more common?
a. Alternators
b. Transformers
c. Transmission lines
d. Underground cables
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14) Which among these is the most severe fault?
a. Single line to ground fault.
b. Double line to ground fault
c. Line to line fault
d. Symmetrical fault.
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15) What is the expression for the symmetrical short circuit current? If the total short circuit current consists of two parts namely symmetrical short circuit current and DC offset current.
a. (Vm / Z) * sin (ω + αt - θ)
b. (Vm / Z) * sin (ωt + α - θ)
c. (Vm * Z) * sin (ωt + αt - θ)
d. (V / Zm) * sin (ωt + α - θ)
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16) Which among the following curves represents the curve for transient current?
a. Only a
b. Only b
c. Only c
d. Only d
e. None of these
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17) On which among the following factors does the magnitude of the fault current depend?
a. Total impedance upto the fault.
b. Voltage at the fault point
c. Both (a) and (b)
d. None of these
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18) Which among the following reactance have a greater value?
a. Sub transient reactance
b. Transient reactance
c. Synchronous reactance
d. All of these
e. None of these
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19) Which among the following methods are generally used for the calculation of symmetrical faults?
a. Norton theorem
b. Thevnin’s theorem
c. Kirchhoff’s laws
d. Only (b) and (c)
e. All of these
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20) What is the multiplication factor to be multiplied with symmetrical momentary current to account for the presence of DC off set current?
a. 1.2
b. 1.5
c. 1.6
d. 2.5
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21) What is the rated breaking capacity of the circuit breaker?
a. The product of rated voltage and rated breaking current
b. The product of rated voltage and rated symmetrical breaking current
c. The product of fault voltage and breaking current
d. None of these
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Answer
Explanation
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ANSWER: The product of rated voltage and rated symmetrical breaking current
Explanation:
No explanation is available for this question!
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22) If the speed of the circuit breaker is 8 cycles or slower than that what will be the multiplying factor?
a. 2.3
b. 1.0
c. 1.5
d. 1.7
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23) What will be the multiplying factor if the speed of the circuit breaker is 2 cycles?
a. 2.2
b. 1.2
c. 2.8
d. 1.4
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24) What is the percentage of occurrence of symmetrical faults?
a. 10 %
b. 15 %
c. 5 %
d. None of these
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25) What does the positive sequence component consist of?
a. Three balanced phasors of equal magnitude and displaced by 120°
b. Three unbalanced phasors displaced by 120°
c. Three phasors with equal magnitude and zero displacement.
d. None of these
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Answer
Explanation
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ANSWER: Three balanced phasors of equal magnitude and displaced by 120°
Explanation:
No explanation is available for this question!
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26) What are zero sequence components?
a. Three balanced phasors of equal magnitude and displaced by 120°
b. Three balanced phasors displaced by 120° and having phase sequence opposite to that of the original phasors.
c. Three phasors with equal magnitude and zero displacement.
d. None of these
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Answer
Explanation
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ANSWER: Three phasors with equal magnitude and zero displacement.
Explanation:
No explanation is available for this question!
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27) Why are series reactors used?
a. Improve the transmission efficiency
b. Improve the power factor of the power system
c. To bring down the fault level with in the capacity of the switchgear instrument
d. All of these
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Answer
Explanation
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ANSWER: To bring down the fault level with in the capacity of the switchgear instrument
Explanation:
No explanation is available for this question!
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28) What is an oriented graph?
a. A connection of network topology, represented by replacing all physical elements by lines.
b. A graph in which the direction is assigned to each branch.
c. A graph where at least one path exists between any two nodes of the graph.
d. None of these
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Answer
Explanation
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ANSWER: A graph in which the direction is assigned to each branch.
Explanation:
No explanation is available for this question!
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29) Which among the following formulae is used for addition of an admittance element into the bus?
a. Yii new = Yii old - y
b. Yii new = Yii old + y
c. Yii new = Yii old - Yij old
d. Yii new = Yii old + Yij old
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30) What is the element of the graph that is not included in the tree called?
a. Links
b. Branches
c. Oriented graph
d. All of these
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31) Why are load flow studies carried out?
a. To study of stability of the system
b. For fault calculations
c. For planning the power system
d. All of these
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32) Which among the following quantities are specified at the load bus?
a. P and Q
b. P and |V|
c. Q and |V|
d. P and δ
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33) Which among the following quantities are specified at the generator bus?
a. P and Q
b. P and |V|
c. Q and |V|
d. P and δ
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34) What percentage of buses in the power system are generator buses?
a. 5 %
b. 25 %
c. 70 %
d. 10 %
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35) Which among the following quantities are to be determined in voltage controlled bus?
a. P and Q
b. Q and |V|
c. |V| and δ
d. Q and δ
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