The Gauss-Seidel load-flow method is

 

Q1. Power is transmitted at high voltage mainly to reduce:

                            (A)    Insulation cost

(B)    I²R losses

(C)   Corona

(D)    Sag

Q2. A single-line diagram represents a 3-phase element by:

     (A)    Three lines

(B)    A single line and symbol

(C)   A circle

(D)    A rectangle

Q3. Generation voltage in a power station is typically around:

(A)    11 kV

(B)    220 kV

(C)   400 kV

(D)    33 kV

Q4. Transmission voltage in India is commonly:

                            (A)    415 V

(B)    11 kV

(C)   220/400 kV

(D)    33 kV

Q5. Domestic single-phase supply voltage is:

                            (A)    415 V

(B)    230 V

(C)   110 V

(D)    33 kV

Q6. If the transmission voltage is doubled for the same power, the line current becomes:

                            (A)    Double

(B)    Half

(C)   Four times

(D)    Same

Q7. If current is halved, the I²R loss becomes:

                            (A)    Half

(B)    One-quarter

(C)   Double

(D)    Same

Q8. The base load of a power system is best supplied by:

                            (A)    Diesel plants

(B)    Thermal/nuclear plants

(C)   Gas turbines

(D)    Pumped storage

 

 

 

                          Q9 The Load factor of the power station is the ratio of :

                            (A)    Peak to average load

(B)    Average to peak load

(C)   Peak to installed capacity

(D)    Average to installed

Q10. The diversity factor is always:

                            (A)    Less than 1

(B)    Greater than or equal to 1

(C)   Equal to 1

(D)    Zero

Q11. A high load factor indicates:

                            (A)    Poor utilisation

(B)    Good/efficient utilisation of plant

(C)   Overloading

(D)    Low demand

Q12. Pumped-storage plants are used mainly for:

                            (A)    Base load

(B)    Peak load and energy storage

(C)   Continuous supply

(D)    Reactive power

Q13. A short transmission line neglects the:

                            (A)    Series resistance

(B)    Shunt capacitance

(C)   Series reactance

(D)    Load

Q14. A medium transmission line lumps the:

                            (A)    Resistance

(B)    Shunt capacitance at ends

(C)   Load

(D)    Sag

Q15. For a short line, the ABCD constants are:

                            (A)    A=D=1, B=Z, C=0

(B)    A=D=0

(C)   B=0, C=Z

(D)    A=Z, D=Y

Q16. For any passive transmission line, the ABCD constants satisfy:

                            (A)    A+D=1

(B)    AD-BC=1

(C)   AB=CD

(D)    A=D

Q17. The unit of the B constant of a transmission line is:

(A)    Ohm

(B)    Siemens

(C)   Dimensionless

(D)    Volt

  

Q18. The unit of the C constant of a transmission line is:

 

 

(B)    ohm

(C)    Siemens (mho)

(D)   Dimensionless

(E)    Ampere

Q19. The A and D constants of a symmetrical line are:

                            (A)    Different

(B)    Equal

(C)   Zero

(D)    Infinite

Q20. No-load receiving-end voltage in terms of A is:

                            (A)    Vs·A

(B)    Vs/A

(C)   Vs·B

(D)    Vs/B

Q21. Voltage regulation of a line is the rise in receiving voltage when:

                            (A)    Load is added

(B)    Full load is removed

(C)   Voltage drops

(D)    Frequency rises

Q22. A line with A=0.9 fed at 245 kV has a no-load receiving voltage of:

                            (A)    220 kV

(B)    245 kV

(C)   272.2 kV

(D)    300 kV

Q23. The surge impedance of a lossless line equals:

                            (A)    sqrt(LC)

(B)    sqrt(L/C)

(C)   LC

(D)    L/C

Q24. The surge impedance loading (SIL) of a line is the load at which:

                            (A)    Voltage is zero

(B)    Reactive power is balanced (flat voltage)

(C)   Current is zero

(D)    Losses are max

Q25. Ferranti effect is the rise of voltage at the end of a long lightly-loaded line:

                            (A)    Sending

(B)    Receiving

(C)   Middle

(D)    Neutral

Q26. The Ferranti effect is caused by the line's:

                            (A)    Resistance

(B)    Shunt capacitance (charging current)

(C)   Inductance

(D)    Load

 

Q27. Long transmission lines (>250 km) are analysed using:

                            (A)    Lumped parameters 

                            (B)    Only resistance

(C)    Distributed Parameter(hyperbolic functions)

(D)      DC analysis

Q28. Bundled conductors are used on EHV lines mainly to reduce:

                            (A)    Weight

(B)    Corona and reactance

(C)   Sag

(D)    Cost

Q29. Skin effect in a conductor causes the current to concentrate:

                            (A)    At the centre

(B)    Near the surface

(C)   Uniformly

(D)    At the ends

Q30. The proximity effect increases the of a conductor:

                            (A)    Capacitance

(B)    Effective resistance

(C)   Length

(D)    Sag

Q31. The electric stress in a cable is maximum at the:

                            (A)    Sheath

(B)    Conductor surface

(C)   Middle of insulation

(D)    Earth

Q32. The most economical conductor radius in a cable satisfies R/r =:

                            (A)    1

(B)    2

(C)   e (2.718)

(D)    10

Q33. Grading of cables is done to obtain:

                            (A)    Higher stress

(B)    Uniform stress distribution

(C)   Lower voltage

(D)    More capacitance

Q34. In a suspension insulator string, the disc with maximum voltage is:

                            (A)    Nearest the tower

(B)    Nearest the line conductor

(C)   In the middle

(D)    All equal

Q35. String efficiency is 100% when the voltage across each disc is:

                            (A)    Zero

(B)    Equal

(C)   Maximum on one

(D)    Different

  

Q36. String efficiency is improved by using a:

                            (A)    Longer string

(B)    Grading (guard) ring 

 

(C)    Higher voltage

(D)    Smaller disc

Q37. Corona occurs when the surface voltage gradient exceeds about:

                            (A)    3 kV/cm

(B)    30 kV/cm (peak)

(C)   300 kV/cm

(D)    0.3 kV/cm

Q38. Corona loss increases with:

                            (A)    Larger diameter

(B)    System voltage and rough surface

(C)   Wider spacing

(D)    Lower voltage

Q39. Corona can be reduced by using:

                            (A)    Thinner conductors

(B)    Larger diameter / hollow conductors

(C)   Higher voltage

(D)    Closer spacing

Q40. The disruptive critical voltage of a line is the voltage at which:

                            (A)    Line melts

(B)    Corona starts

(C)   Insulation fails

(D)    Sag is max

Q41. Corona has the beneficial effect of:

                            (A)    Increasing loss

(B)    Reducing over-voltage surges (acts as a safety valve)

(C)   Increasing voltage

(D)    Reducing spacing

Q42. The sag in a level span is given by:

                            (A)    wL/(8T)

(B)    wL²/(8T)

(C)   wL²/(4T)

(D)    8T/(wL²)

Q43. Sag is directly proportional to the   of the span:

                            (A)    First power

(B)    Square

(C)   Cube

(D)    Square root

Q44. Sag is inversely proportional to the conductor:

                            (A)    Weight

(B)    Tension

(C)   Length

(D)    Diameter

Q45. If the conductor tension is doubled, the sag becomes:

                            (A)    Double

(B)    Half

(C)   Four times

(D)   Same

 

 

 

Q46. The material commonly used for overhead line conductors is:

                            (A)    Copper only

(B)    ACSR (aluminium conductor steel reinforced)

(C)   Iron

(D)    Silver

Q47. ACSR conductors use a steel core to provide:

                            (A)    Conductivity

(B)    Mechanical strength

(C)   Insulation

(D)    Corona

Q48. Insulators for transmission lines are usually made of:

                            (A)    Rubber

(B)    Porcelain / glass / polymer

(C)   Copper

(D)    Steel

Q49. The per-unit value of a quantity is:

                            (A)    Actual x base

(B)    Actual / base

(C)   Actual + base

(D)    Base / actual

Q50. The base impedance is given by:

                            (A)    kV²/MVA

(B)    MVA/kV²

(C)   kV/MVA

(D)    MVA·kV

Q51. Per-unit impedance of a transformer is the same on:

                            (A)    Only HV side

(B)    Only LV side

(C)   Both HV and LV sides

(D)    Neither side

Q52. A 0.2 pu reactance on 100 MVA base becomes         on 50 MVA base (same kV):

                            (A)    0.4 pu

(B)    0.1 pu

(C)   0.2 pu

(D)    0.05 pu

Q53. The diagonal element Yii of the Y-bus is the:

                            (A)    Negative of admittance between buses

(B)    Sum of admittances connected to bus i

(C)   Load at bus i

(D)    Voltage at bus i

Q54. The off-diagonal element Yij of the Y-bus is the:

                            (A)    Sum at bus i

(B)    Negative of the admittance between i and j

(C)   Load current

(D)    Zero

 

                           Q55. The Y-bus matrix is generally:

                            (A)    Full and dense

(B)    Symmetric and sparse

(C)   Non-symmetric

(D)    Diagonal only

Q56. The bus impedance matrix Z-bus is:

                            (A)    Same as Y-bus

(B)    Inverse of Y-bus

(C)   Transpose of Y-bus

(D)    Zero

Q57. In a load-flow study, the slack bus specifies:

                            (A)    P and Q

(B)    V and angle

(C)   P and V

(D)    Q and angle

Q58. A PV (generator) bus specifies:

                            (A)    P and Q

(B)    P and V magnitude

(C)   V and angle

(D)    Q and angle

Q59. A PQ (load) bus specifies:

(A)    P and Q

(B)    V and angle

(C)   P and V

(D)    Q and V

Q60. The Gauss-Seidel load-flow method is:

                             (A)    Fast, complex

(B)    Simple but slow convergence

(C)   Non-iterative

(D)    Only for DC

Q61. The Newton-Raphson method converges in:

                            (A)    Many iterations

(B)    Few iterations (quadratic convergence)

(C)   One step

(D)    Never

Q62. Newton-Raphson is preferred for systems:

                            (A)    Small

(B)    Large

(C)   DC only

(D)    Single bus

Q63. The number of iterations in Newton-Raphson is of system size:

                            (A)    Strongly dependent

(B)    Nearly independent

(C)   Proportional

(D)    Exponential 

Q64. The slack bus supplies the:

 

 

(A)    Fixed Load

(B)    System losses and balance

(C)   Reactive power only

(D)    Nothing

Q65. The primary purpose of load-flow analysis is to find:

                            (A)    Fault currents

(B)    Bus voltages and power flows

(C)   Stability limit

(D)    Insulation level

Q66. A decoupled load-flow exploits the weak coupling between:

                            (A)    P-V and Q-angle

(B)    P-angle and Q-V

(C)   V and I

(D)    R and X

Q67. Reactive power injection at a bus generally the voltage:

                              (A)    Lowers

(B)    Raises

(C)   Does not change

(D)    Reverses

Q68. Power factor of an inductive load is improved by connecting:

                            (A)    Shunt reactor

(B)    Shunt capacitor

(C)   Series resistor

(D)    Series inductor

Q69. A 100 kW load at 0.8 lagging PF needs   kVAR to reach unity PF:

                            (A)    50

(B)    75

(C)   100

(D)    60

Q70. The capacitor kVAR for PF correction is P(tan(phi1) - tan(phi2)) where phi is the:

                            (A)    Voltage angle

(B)    Power-factor angle

(C)   Load angle

(D)    Phase sequence

Q71. An over-excited synchronous condenser supplies   to the system:

                            (A)    Active power

(B)    Leading reactive power (VARs)

(C)   DC

(D)    Harmonics

Q72. On-load tap changers control the:

                            (A)    Frequency

(B)    Voltage

(C)   Power factor of source

(D)    Phase sequence 

Q73. A shunt reactor is used to   voltage on a lightly loaded EHV line:

                            (A)    Raise

(B)   Absorb VARs and lower

(C)   Fix frequency

(D)    Increase current

Q74. A static VAR compensator (SVC) provides:

                            (A)    Fixed reactive power

(B)    Fast, variable reactive power control

(C)   Active power

(D)    DC supply

Q75. Improving the power factor of a plant:

                            (A)    Increases line loss

(B)    Reduces line loss and frees capacity

(C)   Reduces voltage

(D)    Has no effect

Q76. For economic load dispatch, all units operate at equal:

                            (A)    Output power

(B)    Incremental fuel cost (lambda)

(C)   Efficiency

(D)    Voltage

Q77. The incremental fuel cost is the derivative of cost with respect to:

                            (A)    Time

(B)    Power output

(C)   Voltage

(D)    Current

Q78. Transmission losses are accounted for in economic dispatch by:

                            (A)    Ignoring them

(B)    Penalty factors

(C)   Adding fixed cost

(D)    Reducing lambda

Q79. The most economical power factor to which a load should be corrected considers:

                            (A)    Only capacitor cost

(B)    Balance of capacitor cost and kVA demand saving

(C)   Only demand

(D)    Zero cost

Q80. A synchronous condenser used only for reactive power runs at:

(A)    No mechanical load

(B)    Full mechanical load

(C)   Half load

(D)    Zero excitation

Q81. The reactive power (VAR) demand of a system rises when:

                            (A)    PF improves

(B)    Inductive load increases

(C)   Voltage rises

(D)    Load decreases

 

Q82. The main function of a shunt capacitor bank in distribution is:

                            (A)    Frequency control

                             (B)    Power-factor and voltage improvement

                            (C)    Fault in meter

(D) Metering

Q83. A symmetrical (3-phase) fault keeps the system:

                            (A)    Unbalanced

(B)    Balanced

(C)   Open

(D)    De-energised

Q84. The most common type of fault is:

                            (A)    Three-phase

(B)    Line-to-ground (L-G)

(C)   Line-to-line

(D)    Double line-to-ground

Q85. The most severe fault (highest current) is usually the:

                            (A)    L-G

(B)    L-L

(C)   L-L-G

(D)    Three-phase (L-L-L)

Q86. Symmetrical components resolve an unbalanced set into    balanced sets:

                            (A)    Two

(B)    Three (positive, negative, zero)

(C)   Four

(D)    One

Q87. The operator 'a' in symmetrical components equals:

                            (A)    1 angle 90 deg

(B)    1 angle 120 deg

(C)   1 angle 180 deg

(D)    1 angle 60 deg

Q88. The sum 1 + a + a² equals:

                            (A)    1

(B)    0

(C)   3

(D)    a

Q89. For a single line-to-ground fault, the sequence networks are connected in:

                            (A)    Parallel

(B)    Series

(C)   Delta

(D)    Star

Q90. For a line-to-line fault, the positive and negative networks are connected in:

                            (A)    Series

(B)    Parallel

(C)   Series-parallel

(D)    Not connected

Q91. For a double line-to-ground fault, all three sequence networks are in:

(A)    Series

(B)    Parallel

(C)    Open

(D)    Delta 

 

 

    

Q92. For a symmetrical three-phase fault, only the sequence network is used:

                            (A)    Zero

(B)    Negative

(C)   Positive

(D)    All

Q93. Zero-sequence current can flow only if there is a path to:

                            (A)    Line

(B)    Ground (neutral)

(C)   Source

(D)    Load

Q94. A delta winding blocks the flow of   sequence currents to the line:

                            (A)    Positive

(B)    Negative

(C)   Zero

(D)    All

Q95. The positive-sequence impedance of a transmission line     the negative-sequence impedance:

                            (A)    Is greater than

(B)    Equals

(C)   Is less than

(D)    Is unrelated to

Q96. The zero-sequence impedance of a line is usually   the positive-sequence impedance:

                            (A)    Equal to

(B)    Greater than

(C)   Less than

(D)    Zero

Q97. The fault current in per unit equals:

                            (A)    Z_pu

(B)    1/Z_pu

(C)   Z_pu²

(D)    Base MVA

Q98. The short-circuit MVA at a bus equals:

                            (A)    Base MVA x Z_pu

(B)    Base MVA / Z_pu

(C)   1/Base MVA

(D)    Z_pu / Base MVA

Q99. If Z_pu up to a fault is 0.25 on 100 MVA base, the fault MVA is:

                            (A)    25 MVA

(B)    400 MVA

(C)   100 MVA

(D)    250 MVA

Q100. The rating of a circuit breaker is decided by the:

                            (A)    Load current

(B)    Short-circuit (fault) MVA

(C)   Voltage only

(D)    Frequency

 

                             Q101. A current-limiting reactor is used to:

                           (A)    Increase fault current

(B)    Limit fault current

(C)   Improve PF

(D)    Reduce voltage

Q102. The making capacity of a circuit breaker is related to the of fault current:

                            (A)    RMS symmetrical

(B)    Peak (maximum asymmetrical)

(C)   Average

(D)    Steady-state

Q103. The breaking capacity of a breaker is expressed in:

                            (A)    Amperes only

(B)    MVA (or kA at rated kV)

(C)   Volts

(D)    Ohms

Q104. A generator's sub-transient reactance Xd'' is used for calculating the         fault current:

                            (A)    Steady-state

(B)    Initial (first cycle)

(C)   Average

(D)    Zero

Q105. The relay that operates on excess current is the:

                            (A)    Differential

(B)    Over-current

(C)   Distance

(D)    Buchholz

Q106. The relay that compares in and out currents of a zone is the:

                            (A)    Over-current

(B)    Differential

(C)   Distance

(D)    Directional

Q107. The relay used mainly for transmission-line protection is the:

                            (A)    Differential

(B)    Over-current

(C)   Distance (impedance)

(D)    Buchholz

Q108. A distance relay measures the   to determine fault location:

                            (A)    Current only

(B)    Voltage/current ratio (impedance)

(C)   Power

(D)    Frequency

Q109. The Buchholz relay is used for the protection of:

                            (A)    Transmission lines

(B)    Oil-filled transformers

(C)   Generators

(D)    Busbars 

 

Q110. Differential protection is ideal for:

(A)    Long Lines

(B)    Transformers, generators, busbars

(C)   Feeders

(D)    Motors only

Q111. A good protection scheme must primarily be:

                            (A)    Slow

(B)    Selective and fast

(C)   Cheap only

(D)    Manual

Q112. Back-up protection operates when the:

                            (A)    Main protection succeeds

(B)    Main protection fails

(C)   Load increases

(D)    Voltage rises

Q113. Neutral earthing is done to:

                             (A)    Increase fault current only

(B)    Limit over-voltages and provide fault path

(C)   Raise voltage

(D)    Reduce load

Q114. A Peterson coil (arc-suppression coil) is a   used for earthing:

                            (A)    Resistor

(B)    Reactor (inductor)

(C)   Capacitor

(D)    Transformer

Q115. Solid earthing of the neutral gives earth-fault current:

                            (A)    Low

(B)    High

(C)   Zero

(D)    Negative

Q116. Resistance earthing is used to:

                            (A)    Increase fault current

(B)    Limit earth-fault current

(C)   Improve PF

(D)    Raise voltage

Q117. When a circuit breaker interrupts current, the arc is formed and must be:

                            (A)    Increased

(B)    Quenched (extinguished)

(C)   Ignored

(D)    Amplified

Q118. The breaker medium with the best arc-quenching for EHV is:

                            (A)    Oil

(B)    Air

(C)   SF6 gas

(D)    Water

 

Q119. A vacuum circuit breaker is most suitable for        voltage:

                            (A)    Extra-high

                            (B)    Medium   

(C)    DC only

(D)     Zero

Q120. SF6 gas is used in breakers because it has excellent:

                            (A)    Conductivity

(B)    Arc-quenching and dielectric strength

(C)   Weight

(D)    Colour

Q121. The restriking voltage appears across the breaker contacts:

                            (A)    Before opening

(B)    At the instant of arc interruption

(C)   During normal load

(D)    Never

Q122. RRRV stands for:

(A)    Rate of rise of restriking voltage

(B)    Rated relay voltage

(C)   Reactive rise value

(D)    None

Q123. The arc in a breaker is finally extinguished at:

                            (A)    Voltage peak

(B)    Current zero

(C)   Current peak

(D)    Voltage zero

Q124. Auto-reclosing of breakers is used because most line faults are:

                            (A)    Permanent

(B)    Transient (temporary)

(C)   Internal

(D)    Three-phase

Q125. The purpose of a lightning arrester is to:

                            (A)    Increase voltage

(B)    Divert surge to earth

(C)   Store energy

(D)    Improve PF

Q126. An isolator (disconnector) is operated:

                            (A)    On load

(B)    Off load (no current)

(C)   During fault

(D)    At any time

Q127. Carrier-current protection is a form of protection for long lines:

                            (A)    Over-current

(B)    Pilot (unit)

(C)   Thermal

(D)    Buchholz

Q128. The pick-up value of a relay is the current at which it:

                             (A)    Resets

(B)    melts

(C)    Just operates 

(D) Trips instantly

Q129. Stability is the ability of a system to return to synchronism after a:

                            (A)    Load increase

(B)    Disturbance

(C)   Voltage rise

(D)    Frequency drop

Q130. Steady-state stability concerns   disturbances:

                            (A)    Large sudden

(B)    Small slow

(C)   Zero

(D)    Fault

Q131. Transient stability concerns a   disturbance such as a fault:

                            (A)    Small

(B)    Large sudden

(C)   Slow

(D)    Steady

Q132. The swing equation relates accelerating power to the:

                             (A)    Voltage

(B)    Rate of change of rotor angle

(C)   Current

(D)    Frequency

Q133. In the swing equation M d²delta/dt² = Pm - Pe, M is the:

                            (A)    Load

(B)    Inertia constant

(C)   Resistance

(D)    Reactance

Q134. The power-angle equation is Pe =:

                            (A)    (EV/X) cos(delta)

(B)    (EV/X) sin(delta)

(C)   EV/X

(D)    (E/V) sin(delta)

Q135. Maximum power transfer occurs at a load angle of:

                              (A)    0 deg

(B)    45 deg

(C)   90 deg

(D)    180 deg

Q136. The swing curve is a plot of rotor angle versus:

                            (A)    Power

(B)    Time

(C)   Voltage

(D)    Frequency

Q137. By the equal-area criterion, the system is stable if:

                            (A)    A1 > A2

(B)    A1 = A2 is achievable

(C)   No area

(D)   A1 < A2 always 

 

 

Q138. A1 in the equal-area criterion is the area:

                               (A)    Decelerating

(B)    Accelerating

(C)   Zero

(D)    Load

Q139. The maximum angle for stable fault clearing is the:

                            (A)    Load angle

(B)    Critical clearing angle

(C)   Torque angle

(D)    Zero angle

Q140. The time corresponding to the critical clearing angle is the:

                              (A)    Fault time

(B)    Critical clearing time

(C)   Reset time

(D)    Cycle time

Q141. Faster fault clearing    transient stability:

                            (A)    Worsens

(B)    Improves

(C)   Does not affect

(D)    Reverses

Q142. Stability is improved by    the transfer reactance:

                            (A)    Increasing

(B)    Reducing

(C)   Doubling

(D)    Ignoring

Q143. Series capacitors improve stability by:

                             (A)    Increasing reactance

(B)    Reducing net line reactance

(C)   Adding resistance

(D)    Raising frequency

Q144. High-speed excitation and AVR improve:

                             (A)    Load factor

(B)    Transient stability

(C)   Corona

(D)    Sag

Q145. The steady-state stability limit is the maximum power at delta =:

                            (A)    0 deg

(B)    45 deg

(C)   90 deg

(D)    180 deg

Q146. Dynamic stability includes the effect of:

                            (A)    No controllers

(B)    Automatic controllers (AVR, governor)

(C)   Only faults

(D)    Only load

 

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            Q147. Loss of synchronism means the machine’s rotor angle :

                            (A)    Settles

(B)    Keeps increasing without bound

(C)   Becomes zero

(D)    Reverses once

Q148. A power system stabiliser (PSS) is used to damp:

                            (A)    Voltage

(B)    Low-frequency oscillations

(C)   Harmonics

(D)    Faults

Q149. Inertia constant H of a machine is expressed in:

                            (A)    Ohms

(B)    MJ/MVA (seconds)

(C)   Amperes

(D)    Volts

Q150. Increasing the inertia of a machine generally transient stability:

                            (A)    Reduces

(B)    Improves

(C)   Does not affect

(D)   Reverses