ELECTRICAL ENGINEERING- PAGE 7
ELECTRICAL ENGINEERING MCQs- PAGE 7
1. A coil has a resistance of 100 Ω at 25 deg C and 200 Ω at 100 deg C. Its temperature coefficient at 0 deg C is __________ per degree Celsius.
(A) 0.002 (B) 0.02 (C) 0.2 (D) None of the above
Ans: B
2. Current flowing in an electric circuit is equivalent to __________ in magnetic circuit.
(A) Flux (B) MMF (C) Reluctance (D) Permeance
Ans: A
3. The angular frequency of a 50 Hz sine wave is __________ rad/sec.
(A) 50/π (B) 50 π (C) 100/π (D) 100 π
Ans: D
4. The resonance frequency of an RLC series circuit is 100 Hz. If the resistance value is doubled, keeping all other parameters same, what would be the new resonance frequency ?
(A) 25 Hz (B) 50 Hz (C) 100 Hz (D) 200 Hz
Ans: C
5. A power system has 100 buses including 10 generator buses. For the load flow analysis using Newton-Raphson method in polar coordinates, the size of the Jacobian is
(A) 189 x 189 (B) 100 x 100 (C) 90 x 90 (D) 180 x 180
Ans: A
6. The inductance and capacitance of a 400 kV, three-phase, 50 Hz lossless transmission line are 1.6 mH/km/phase and 10 nF/km/phase respectively. The sending end voltage is maintained at 400 kV. To maintain a voltage of 400 kV at the receiving end, when the line is delivering 300 MW load, the shunt compensation required is
(A) capacitive (B) inductive (C) resistive (D) zero
Ans: B
7. The direction of rotation of a single-phase capacitor run induction motor is reversed by
(A) interchanging the terminals of the AC supply.
(B) interchanging the terminals of the capacitor.
(C) interchanging the terminals of the auxiliary winding.
(D) interchanging the terminals of both the windings.
Ans: C
8. The graph associated with an electrical network has 7 branches and 5 nodes. The number of independent KCL equations and the number of independent KVL equations, respectively, are
(A) 2 and 5 (B) 5 and 2 (C) 3 and 4 (D) 4 and 3
Ans: D
9. A temperature in the range of −40˚ C to 55˚ C is to be measured with a resolution of 0.1˚ C. The minimum number of ADC bits required to get a matching dynamic range of the temperature sensor is
(A) 8 (B) 10 (C) 12 (D) 14
Ans: B
10. In a constant V/f induction motor drive, the slip at the maximum torque
(A) is directly proportional to the synchronous speed.
(B) remains constant with respect to the synchronous speed.
(C) has an inverse relation with the synchronous speed.
(D) has no relation with the synchronous speed.
Ans: C
11. In a 100 bus power system, there are 10 generators. In a particular iteration of Newton Raphson load flow technique (in polar coordinates), two of the PV buses are converted to PQ type. In this iteration,
(A) the number of unknown voltage angles increases by two and the number of unknown voltage magnitudes increases by two.
(B) the number of unknown voltage angles remains unchanged and the number of unknown voltage magnitudes increases by two.
(C) the number of unknown voltage angles increases by two and the number of unknown voltage magnitudes decreases by two.
(D) the number of unknown voltage angles remains unchanged and the number of unknown voltage magnitudes decreases by two.
Ans: B
12. Consider a system consisting of a synchronous generator working at a lagging power factor, a synchronous motor working at an overexcited condition and a directly grid-connected induction generator. Consider capacitive VAr to be a source and inductive VAr to be a sink of reactive power. Which one of the following statements is TRUE?
(A) Synchronous motor and synchronous generator are sources and induction generator is a sink of reactive power.
(B) Synchronous motor and induction generator are sources and synchronous generator is a sink of reactive power.
(C) Synchronous motor is a source and induction generator and synchronous generator are sinks of reactive power.
(D) All are sources of reactive power.
Ans: A
13. A single-phase thyristor-bridge rectifier is fed from a 230 V, 50 Hz, single-phase AC mains. If it is delivering a constant DC current of 10 A, at firing angle of 30 deg , then value of the power factor at AC mains is
(A) 0.87 (B) 0.9 (C) 0.78 (D) 0.45
Ans: C
14. A single-phase, 22 kVA, 2200 V/ 220 V, 50 Hz, distribution transformer is to be connected as an auto-transformer to get an output voltage of 2420 V. Its maximum kVA rating as an autotransformer is
(A) 22 (B) 24.2 (C) 242 (D) 2420
Ans: C
15. A single-phase full-bridge voltage source inverter (VSI) is fed from a 300 V battery. A pulse of 120 deg duration is used to trigger the appropriate devices in each half-cycle. The rms value of the fundamental component of the output voltage, in volts, is
(A) 234 (B) 245 (C) 300 (D) 331
Ans: A
(A) 0.002 (B) 0.02 (C) 0.2 (D) None of the above
Ans: B
2. Current flowing in an electric circuit is equivalent to __________ in magnetic circuit.
(A) Flux (B) MMF (C) Reluctance (D) Permeance
Ans: A
3. The angular frequency of a 50 Hz sine wave is __________ rad/sec.
(A) 50/π (B) 50 π (C) 100/π (D) 100 π
Ans: D
4. The resonance frequency of an RLC series circuit is 100 Hz. If the resistance value is doubled, keeping all other parameters same, what would be the new resonance frequency ?
(A) 25 Hz (B) 50 Hz (C) 100 Hz (D) 200 Hz
Ans: C
5. A power system has 100 buses including 10 generator buses. For the load flow analysis using Newton-Raphson method in polar coordinates, the size of the Jacobian is
(A) 189 x 189 (B) 100 x 100 (C) 90 x 90 (D) 180 x 180
Ans: A
6. The inductance and capacitance of a 400 kV, three-phase, 50 Hz lossless transmission line are 1.6 mH/km/phase and 10 nF/km/phase respectively. The sending end voltage is maintained at 400 kV. To maintain a voltage of 400 kV at the receiving end, when the line is delivering 300 MW load, the shunt compensation required is
(A) capacitive (B) inductive (C) resistive (D) zero
Ans: B
7. The direction of rotation of a single-phase capacitor run induction motor is reversed by
(A) interchanging the terminals of the AC supply.
(B) interchanging the terminals of the capacitor.
(C) interchanging the terminals of the auxiliary winding.
(D) interchanging the terminals of both the windings.
Ans: C
8. The graph associated with an electrical network has 7 branches and 5 nodes. The number of independent KCL equations and the number of independent KVL equations, respectively, are
(A) 2 and 5 (B) 5 and 2 (C) 3 and 4 (D) 4 and 3
Ans: D
9. A temperature in the range of −40˚ C to 55˚ C is to be measured with a resolution of 0.1˚ C. The minimum number of ADC bits required to get a matching dynamic range of the temperature sensor is
(A) 8 (B) 10 (C) 12 (D) 14
Ans: B
10. In a constant V/f induction motor drive, the slip at the maximum torque
(A) is directly proportional to the synchronous speed.
(B) remains constant with respect to the synchronous speed.
(C) has an inverse relation with the synchronous speed.
(D) has no relation with the synchronous speed.
Ans: C
11. In a 100 bus power system, there are 10 generators. In a particular iteration of Newton Raphson load flow technique (in polar coordinates), two of the PV buses are converted to PQ type. In this iteration,
(A) the number of unknown voltage angles increases by two and the number of unknown voltage magnitudes increases by two.
(B) the number of unknown voltage angles remains unchanged and the number of unknown voltage magnitudes increases by two.
(C) the number of unknown voltage angles increases by two and the number of unknown voltage magnitudes decreases by two.
(D) the number of unknown voltage angles remains unchanged and the number of unknown voltage magnitudes decreases by two.
Ans: B
12. Consider a system consisting of a synchronous generator working at a lagging power factor, a synchronous motor working at an overexcited condition and a directly grid-connected induction generator. Consider capacitive VAr to be a source and inductive VAr to be a sink of reactive power. Which one of the following statements is TRUE?
(A) Synchronous motor and synchronous generator are sources and induction generator is a sink of reactive power.
(B) Synchronous motor and induction generator are sources and synchronous generator is a sink of reactive power.
(C) Synchronous motor is a source and induction generator and synchronous generator are sinks of reactive power.
(D) All are sources of reactive power.
Ans: A
13. A single-phase thyristor-bridge rectifier is fed from a 230 V, 50 Hz, single-phase AC mains. If it is delivering a constant DC current of 10 A, at firing angle of 30 deg , then value of the power factor at AC mains is
(A) 0.87 (B) 0.9 (C) 0.78 (D) 0.45
Ans: C
14. A single-phase, 22 kVA, 2200 V/ 220 V, 50 Hz, distribution transformer is to be connected as an auto-transformer to get an output voltage of 2420 V. Its maximum kVA rating as an autotransformer is
(A) 22 (B) 24.2 (C) 242 (D) 2420
Ans: C
15. A single-phase full-bridge voltage source inverter (VSI) is fed from a 300 V battery. A pulse of 120 deg duration is used to trigger the appropriate devices in each half-cycle. The rms value of the fundamental component of the output voltage, in volts, is
(A) 234 (B) 245 (C) 300 (D) 331
Ans: A
16) The stator of a 415V, 50 Hz, 4-pole slip ring Induction Motor is excited by rated frequency with slip rings open circuited. The rotor is made to rotate at a speed of 600 rpm in the opposite direction to the normal direction, The frequency of induced voltage across slip ring is
A) 30 Hz
B) 70 Hz
C) 20 Hz
D) 35 Hz
Ans: B
17) A DC shunt motor has rated rpm of 480. Certain industrial application requires this motor to run at 540 rpm for some time. Which speed control will be desirable?
A) Ward Leonard control
B) Armature current control
C) Field resistance control
D) It is not possible to run the motor at more than the rated rpm
Ans: C
18) Capacitance grading of cable implies
A) grading according to capacitance of cables per kilometer length
B) cables using single dielectric in different concentrations
C) use of dielectrics of different permeabilities
D) capacitance required to be introduced at different length to counter the effect of inductance
Ans: C
19) One out of the following statements is not true:
A) The curl of gradient of any scalar field is identically zero
B) The divergence of curl of any vector field is identically zero
C) A field, which has zero divergence, is said to be solenoidal
D) A field, whose curl is zero, is said to be rotational
Ans: D
20) In a loss-free R-L-C circuit the transient current will be:
A) Oscillating
B) Non-oscillating
C) Sinusoidal wave
D) Square wave
Ans: C
21) Which statement out of the following is a wrong statement with regard to Induction motor?
A) Auto-transformer starter is costlier to “direct on line” (DOL) starter
B) DOL starter is used for motors up to 5 horse power only
C) Auto transformer starter is used for motors up to 20 horse power only
D) Star delta starter connects the motor first in delta at the time of starting then in star for running
Ans: D
22) In the measurement of power of balanced load by two wattmeter method in a 3-phase circuit, The readings of the wattmeters are 4 kW and 2 kW respectively, the later is being taken after reversing the connections of current coil. the power factor and reactive power of the load is
A) 0.2 & 6 kVAR
B) 0.2 & 6 √3 kVAR
C) 0.32 & 2 kVAR
D) 0.32 & 2 √3 kVAR
Ans: B
23) The RMS value of a half-wave rectified current is 10 Ampere. Its value for full-wave rectification would be:
A) 10 Ampere
B) 14.14 Ampere
C) 31.4 Ampere
D) 20 Ampere
Ans: B
24) One of the following does not represent a valid combination of ‘Class’ of insulating material and its limiting temperature in 'Degree Centigrade'.
A) ‘Class- A’ – 105 deg C
B) ‘Class- F’ – 155 deg C
C) ‘Class- H’ – 180 deg C
D) ‘Class- B’ – 120 deg C
Ans: D
25) In which of the following power plants the availability of power is least reliable?
A) Solar power plant
B) Wind energy
C) Tidal power plant
D) Geothermal power plant
Ans: B
26) Overall thermal efficiency of a steam power station in India is in the range:
A) 18-24 percent
B) 30-40 percent
C) 44-62 percent
D) 68-79 percent
Ans: B
27) The burden value in Potential Transformer (PT) should be ______ to achieve low errors in PT:
A) low
B) high
C) medium
D) infinite
Ans: B
28) For complete protection of a three-phase line:
A) three Phase relays and three Earth fault relays are required
B) three Phase relays and two Earth fault relays are required
C) two Phase relays and two Earth fault relays are required
D) two Phase relays and one Earth fault relay are required
Ans: D
29) Which one is not a valid condition for the wave winding?
A) Back pitch and front pitch are of the same sign
B) Back pitch and front pitch are odd numbers
C) Back pitch and front pitch may differ by two and may be equal also
D) Commutator pitch is always unity
Ans: D
30) For rural electrification in a country like India with complex networks, it is preferable to use:
A) Air circuit breaker
B) Oil circuit breaker
C) Vacuum circuit breaker
D) Minimum oil circuit breaker
Ans: C
31) Which of the following statements is incorrect?
A) During parallel resonance impedance at resonance is minimum
B) During parallel resonance current is magnified
C) During series resonance current at resonance is maximum
D) During series as well as parallel resonance, the power factor is unity
Ans: A
32) One of the following is not a valid statement:
A) Fleming’s right hand rule is used to find out the direction of current in the conductor of a generator
B) Fleming’s left hand rule is used to find out the direction of rotation of the armature of DC motor
C) Ampere’s rule is used to find out the direction of lines of force around the wire carrying current
D) Right hand thumb rule is used to find out the direction of counter current produced in the armature magnetic field
Ans: D
33) The number of electrical degrees ‘passed through’ in one revolution of a 6-pole synchronous alternator is:
A) 360 degree
B) 720 degree
C) 1080 degree
D) 2160 degree
Ans: C
34) Following is not the property of a complete incidence matrix:
A) Algebraic sum of the column entries of an incidence matrix is zero
B) The rank of a complete incidence matrix of a connected graph is (n - 1), where n is total number of nodes
C) Order of a complete incidence matrix will be (n*b), where b is total number of branches and n is total number of nodes
D) Determinant of the incidence matrix of a closed loop is not zero.
Ans: D
35) An ideal current source has zero:
A) internal resistance
B) internal conductance
C) voltage at no-load
D) ripples
Ans: B
36) If the frequency of input voltage of a transformer is increased keeping the magnitude of voltage unchanged, then:
A) both hysteresis loss and eddy current loss in the core will increase
B) hysteresis loss will increase but eddy current loss will decrease
C) hysteresis loss will decrease but eddy current loss will increase
D) hysteresis loss will decrease but eddy current loss will remain unchanged
Ans: D
37) The superposition theorem is applicable to:
A) linear response only
B) linear and non-linear response
C) non-linear and time-variant response
D) linear, non-linear and time-variant response
Ans: A
38) Which motor is generally used in Tap Recorders?
A) universal motor
B) reluctance motor
C) split phase motor
D) hysteresis motor
Ans: D
39) A gas turbine works on:
A) Carnot cycle
B) Brayton cycle
C) Dual cycle
D) Rankine cycle
Ans: B
40) In practice, a current source inverter consists of an AC/ DC converter with a large inductance ‘L’ in the output. This inductance maintains a ……… …………through the switching devices over short interval of time.
A) constant current
B) constant voltage
C) constant power
D) none of the (A), (B), (C)
Ans: A
41) If the input to a differentiating circuit is a saw-tooth wave, then output will be …………….. wave:
A) square
B) rectangular wave
C) triangular wave
D) rectified sine wave
Ans: B
42) A unit ramp function when integrated yields:
A) unit parabolic function
B) unit ramp function
C) unit doublet
D) unit impulse function
Ans: A
43) Which of the following statements is not valid in case of conductors in electrostatic fields?
A) The static electric field intensity inside a conductor is zero
B) The static electric field intensity at the surface of a conductor is everywhere directed normal to the surface
C) The conductor surface is an equivalent potential surface
D) None of the above
Ans: D
44) The leakage flux in a transformer depends upon:
A) load current
B) load current and voltage
C) load current, voltage and frequency
D) load current, voltage, frequency and power factor
Ans: A
45) Which of the following company is associated with manufacture of high capacity transformers in India?
A) M/S National Thermal Power Corporation Limited
B) M/S Bharat Heavy Electricals Limited
C) M/S Heavy Engineering Corporation Limited
D) M/S Electricity Authority of India
Ans: B
46) In case of semi-conductors, the ratio of conduction current to displacement current is:
A) more than 200 and less than 1000
B) less than 100 but greater than 1/100
C) less than 1/100
D) more than 1000
Ans: B
47) A large hydropower station has a head of 324 metre and an average flow of 1370 metre3/second. The available hydraulic power from this station will be:
A) 4.35 MW
B) 4.15 MW
C) 4.47 MW
D) 4.73 MW
Ans: A
48) Which among the given statement is/are CORRECT.
(a) Avalanche breakdown voltage increases with temperature
(b) Zener breakdown voltage decreases with temperature
A) Only (a)
B) Only (b)
C) Both (a) & (b)
D) None of (a) & (b)
Ans: C
49) The operation of the relay which is most affected due to arc resistance is
A) Mho relay
B) Reactance relay
C) Impedance relay
D) All are equally affected
Ans: A
50) An 8-pole alternator runs at 750 rpm and supplies power to a 6-pole induction motor which has a full load slip of 3 percent. The full load speed of the induction motor will be:
A) 1000 rpm
B) 920 rpm
C) 950 rpm
D) 970 rpm
Ans: D
A) 30 Hz
B) 70 Hz
C) 20 Hz
D) 35 Hz
Ans: B
17) A DC shunt motor has rated rpm of 480. Certain industrial application requires this motor to run at 540 rpm for some time. Which speed control will be desirable?
A) Ward Leonard control
B) Armature current control
C) Field resistance control
D) It is not possible to run the motor at more than the rated rpm
Ans: C
18) Capacitance grading of cable implies
A) grading according to capacitance of cables per kilometer length
B) cables using single dielectric in different concentrations
C) use of dielectrics of different permeabilities
D) capacitance required to be introduced at different length to counter the effect of inductance
Ans: C
19) One out of the following statements is not true:
A) The curl of gradient of any scalar field is identically zero
B) The divergence of curl of any vector field is identically zero
C) A field, which has zero divergence, is said to be solenoidal
D) A field, whose curl is zero, is said to be rotational
Ans: D
20) In a loss-free R-L-C circuit the transient current will be:
A) Oscillating
B) Non-oscillating
C) Sinusoidal wave
D) Square wave
Ans: C
21) Which statement out of the following is a wrong statement with regard to Induction motor?
A) Auto-transformer starter is costlier to “direct on line” (DOL) starter
B) DOL starter is used for motors up to 5 horse power only
C) Auto transformer starter is used for motors up to 20 horse power only
D) Star delta starter connects the motor first in delta at the time of starting then in star for running
Ans: D
22) In the measurement of power of balanced load by two wattmeter method in a 3-phase circuit, The readings of the wattmeters are 4 kW and 2 kW respectively, the later is being taken after reversing the connections of current coil. the power factor and reactive power of the load is
A) 0.2 & 6 kVAR
B) 0.2 & 6 √3 kVAR
C) 0.32 & 2 kVAR
D) 0.32 & 2 √3 kVAR
Ans: B
23) The RMS value of a half-wave rectified current is 10 Ampere. Its value for full-wave rectification would be:
A) 10 Ampere
B) 14.14 Ampere
C) 31.4 Ampere
D) 20 Ampere
Ans: B
24) One of the following does not represent a valid combination of ‘Class’ of insulating material and its limiting temperature in 'Degree Centigrade'.
A) ‘Class- A’ – 105 deg C
B) ‘Class- F’ – 155 deg C
C) ‘Class- H’ – 180 deg C
D) ‘Class- B’ – 120 deg C
Ans: D
25) In which of the following power plants the availability of power is least reliable?
A) Solar power plant
B) Wind energy
C) Tidal power plant
D) Geothermal power plant
Ans: B
26) Overall thermal efficiency of a steam power station in India is in the range:
A) 18-24 percent
B) 30-40 percent
C) 44-62 percent
D) 68-79 percent
Ans: B
27) The burden value in Potential Transformer (PT) should be ______ to achieve low errors in PT:
A) low
B) high
C) medium
D) infinite
Ans: B
28) For complete protection of a three-phase line:
A) three Phase relays and three Earth fault relays are required
B) three Phase relays and two Earth fault relays are required
C) two Phase relays and two Earth fault relays are required
D) two Phase relays and one Earth fault relay are required
Ans: D
29) Which one is not a valid condition for the wave winding?
A) Back pitch and front pitch are of the same sign
B) Back pitch and front pitch are odd numbers
C) Back pitch and front pitch may differ by two and may be equal also
D) Commutator pitch is always unity
Ans: D
30) For rural electrification in a country like India with complex networks, it is preferable to use:
A) Air circuit breaker
B) Oil circuit breaker
C) Vacuum circuit breaker
D) Minimum oil circuit breaker
Ans: C
31) Which of the following statements is incorrect?
A) During parallel resonance impedance at resonance is minimum
B) During parallel resonance current is magnified
C) During series resonance current at resonance is maximum
D) During series as well as parallel resonance, the power factor is unity
Ans: A
32) One of the following is not a valid statement:
A) Fleming’s right hand rule is used to find out the direction of current in the conductor of a generator
B) Fleming’s left hand rule is used to find out the direction of rotation of the armature of DC motor
C) Ampere’s rule is used to find out the direction of lines of force around the wire carrying current
D) Right hand thumb rule is used to find out the direction of counter current produced in the armature magnetic field
Ans: D
33) The number of electrical degrees ‘passed through’ in one revolution of a 6-pole synchronous alternator is:
A) 360 degree
B) 720 degree
C) 1080 degree
D) 2160 degree
Ans: C
34) Following is not the property of a complete incidence matrix:
A) Algebraic sum of the column entries of an incidence matrix is zero
B) The rank of a complete incidence matrix of a connected graph is (n - 1), where n is total number of nodes
C) Order of a complete incidence matrix will be (n*b), where b is total number of branches and n is total number of nodes
D) Determinant of the incidence matrix of a closed loop is not zero.
Ans: D
35) An ideal current source has zero:
A) internal resistance
B) internal conductance
C) voltage at no-load
D) ripples
Ans: B
36) If the frequency of input voltage of a transformer is increased keeping the magnitude of voltage unchanged, then:
A) both hysteresis loss and eddy current loss in the core will increase
B) hysteresis loss will increase but eddy current loss will decrease
C) hysteresis loss will decrease but eddy current loss will increase
D) hysteresis loss will decrease but eddy current loss will remain unchanged
Ans: D
37) The superposition theorem is applicable to:
A) linear response only
B) linear and non-linear response
C) non-linear and time-variant response
D) linear, non-linear and time-variant response
Ans: A
38) Which motor is generally used in Tap Recorders?
A) universal motor
B) reluctance motor
C) split phase motor
D) hysteresis motor
Ans: D
39) A gas turbine works on:
A) Carnot cycle
B) Brayton cycle
C) Dual cycle
D) Rankine cycle
Ans: B
40) In practice, a current source inverter consists of an AC/ DC converter with a large inductance ‘L’ in the output. This inductance maintains a ……… …………through the switching devices over short interval of time.
A) constant current
B) constant voltage
C) constant power
D) none of the (A), (B), (C)
Ans: A
41) If the input to a differentiating circuit is a saw-tooth wave, then output will be …………….. wave:
A) square
B) rectangular wave
C) triangular wave
D) rectified sine wave
Ans: B
42) A unit ramp function when integrated yields:
A) unit parabolic function
B) unit ramp function
C) unit doublet
D) unit impulse function
Ans: A
43) Which of the following statements is not valid in case of conductors in electrostatic fields?
A) The static electric field intensity inside a conductor is zero
B) The static electric field intensity at the surface of a conductor is everywhere directed normal to the surface
C) The conductor surface is an equivalent potential surface
D) None of the above
Ans: D
44) The leakage flux in a transformer depends upon:
A) load current
B) load current and voltage
C) load current, voltage and frequency
D) load current, voltage, frequency and power factor
Ans: A
45) Which of the following company is associated with manufacture of high capacity transformers in India?
A) M/S National Thermal Power Corporation Limited
B) M/S Bharat Heavy Electricals Limited
C) M/S Heavy Engineering Corporation Limited
D) M/S Electricity Authority of India
Ans: B
46) In case of semi-conductors, the ratio of conduction current to displacement current is:
A) more than 200 and less than 1000
B) less than 100 but greater than 1/100
C) less than 1/100
D) more than 1000
Ans: B
47) A large hydropower station has a head of 324 metre and an average flow of 1370 metre3/second. The available hydraulic power from this station will be:
A) 4.35 MW
B) 4.15 MW
C) 4.47 MW
D) 4.73 MW
Ans: A
48) Which among the given statement is/are CORRECT.
(a) Avalanche breakdown voltage increases with temperature
(b) Zener breakdown voltage decreases with temperature
A) Only (a)
B) Only (b)
C) Both (a) & (b)
D) None of (a) & (b)
Ans: C
49) The operation of the relay which is most affected due to arc resistance is
A) Mho relay
B) Reactance relay
C) Impedance relay
D) All are equally affected
Ans: A
50) An 8-pole alternator runs at 750 rpm and supplies power to a 6-pole induction motor which has a full load slip of 3 percent. The full load speed of the induction motor will be:
A) 1000 rpm
B) 920 rpm
C) 950 rpm
D) 970 rpm
Ans: D
51) For AC networks, as per maximum power transfer theorem, for maximum power transfer, the source impedance should be equal to:
A) twice the load impedance
B) complex conjugate of load impedance
C) twice the complex conjugate of load impedance
D) none of these
Ans: B
52) In power station practice “spinning reserve” is:
A) reserve generating capacity that is in operation but not in service
B) reserve generating capacity that is connected to bus and ready to take the load
C) reserve generating capacity that is available for service but not in operation
D) capacity of the part of the plant that remains under maintenance
Ans: B
53) Which of the following plants will take least time in starting from cold conditions to full-load operation?
A) Nuclear power plant
B) Steam power plant
C) Hydro-electric power plant
D) Gas turbine plant
Ans: C
54) Which of the following are the basic elements in a 555 timer IC?
(a) Two comparators
(b) A flip-flop
(c) A discharge transistor
(d) A resistive voltage divider
A) (a), (b) and (d)
B) only (a), (b) and (c)
C) only (b), (c) and (d)
D) only (a), (b), (c) and (d)
Ans: D
55) Which waveform out of the following waves has the least value of form-factor:
A) Triangular wave
B) Square wave
C) Rectangular wave
D) Sine wave
Ans: B
56) Which type of protection is provided on a generator to protect against stator insulation failure?
A) Differential protection
B) Overcurrent relay
C) Thermocouple actuated alarm
D) Reverse power relay
Ans: A
57) In an alternator if the winding is short pitched by 60 electrical degrees, its pitch factor will be:
A) 1.0
B) 0.866
C) 0.75
D) 0.50
Ans: B
58) The inertia constant of a 100 MVA, 11 kV water wheel generator is 4. The energy stored in the rotor at the synchronous speed is:
A) 400 Mega Joule
B) 400 Kilo Joule
C) 25 Mega Joule
D) 25 Kilo Joule
Ans: A
53) The reflection coefficient of a short-circuited line for voltage is:
A) -1
B) +1
C) 0.5
D) zero
Ans: A
54) The typical ratio of latching current to holding current in a 20A thyristor is
A) 5.0
B) 2.0
C) 1.0
D) 0.5
Ans: B
55) If the primary fault current is 2000 ampere, the relay setting current is 50 percent and the CT ratio is 400/5, then the plug-setting multiplier is:
A) 25
B) 15
C) 50
D) None of the above
Ans: D
56) Highest flux density exists inside which of the following instruments?
A) Electrodynamic instruments
B) Hot wire instruments
C) Moving iron instruments
D) Moving coil instruments
Ans: D
57) The current gain of emitter follower is:
A) less than one
B) more than one
C) zero
D) unpredictable
Ans: B
58) Which statement out of the following statements about ‘corona’ is incorrect?
A) Corona gives rise to radio interference
B) Corona results in loss of power in transmission
C) Corona discharge can be observed as red luminescence
D) Corona is always accompanied by a hissing voice
Ans: C
59) A three-phase transformer, connected in star-delta, is composed of three single-phase transformers, each rated 127/ 13.2 kV. The line-to-line voltage ratio for the three-phase transformer is:
A) 220 / 13.2 kV
B) 127 / 13.2 kV
C) 127 / 220 kV
D) 220 / 220 kV
Ans: A
60) Synchronous wattage of induction motor means:
A) rotor input in watts
B) stator input in watts
C) combined stator and rotor input in watts
D) shaft output in watts
Ans: A
61) The average power delivered to an impedance 4 − j 3 Ω by a current 5Cos(100πt + 100) Ampere is
A) 44.2 W
B) 50 W
C) 62.5 W
D) 125 W
Ans: B
62) Two 220 volt lamps, one of 60 watt and the other of 75 watt are connected in series across a 440 volt supply. The potential difference across 60 watt lamp will be:
A) 195 volt
B) 220 volt
C) 245 volt
D) 440 volt
Ans: C
63) The load-flow solution is always assured in case of:
A) Newon-Raphson method
B) Gauss-Seidal method
C) Fast Decoupled method
D) None of these methods guarantee
Ans: A
64) Full load current of an Induction motor is 20 Ampere. The no-load current may be expected to be:
A) 25 Ampere to 28 Ampere
B) 15 Ampere to 18 Ampere
C) 11 Ampere to 14 Ampere
D) 6 Ampere to 10 Ampere
Ans: D
65) Which of the following relation is incorrect?
A) capacity factor = utilization factor x load factor
B) load factor x maximum load = average load
C) demand factor x connected load = maximum demand
D) none of these
Ans: D
66) The inrush current of a transformer at no-load is maximum, if it is switched-on when the supply voltage is at:
A) zero voltage value
B) at peak voltage value
C) at half of the peak voltage value
D) at 0.866 of the peak voltage value
Ans: A
67) A DC reactor is connected in series with each pole of a converter station in order to:
A) prevent commutation failures in the inverter
B) supply reactive power to the converter
C) improve system stability
D) increase the power transfer capability
Ans: A
68) Two stator windings of AC servomotors are oriented:
A) 90 degree (mechanical) apart
B) 90 degree (electrical) apart
C) 180 degree (mechanical) apart
D) 180 degree (electrical) apart
Ans: B
69) A 10A DC Ammeter has a resistance of 0.1 Ω is to be extended to 50 A, the required shunt wire is
A) Manganin wire of 20 m Ω
B) Constantan wire of 20 m Ω
C) Manganin wire of 25 m Ω
D) Constantan wire of 25 m Ω
Ans: C
70) Two single-phase 150 kVA, 7200/ 600 volt transformers are connected in open-delta. The maximum three-phase load that they can carry is:
A) 300 kVA
B) 75 kVA
C) 259 kVA
D) 249 kVA
Ans: C
71) A DC Motor develops a torque of 150 N-m. A 10 percent reduction in the field flux causes a 50 percent increase in armature current. The new value of torque is:
A) 102.5 N-m
B) 202.5 N-m
C) 172.5 N-m
D) 232.5 N-m
Ans: B
72) Natural commutation means:
A) reducing the thyristor current to zero
B) reducing the thyristor current below “holding current”
C) reducing the current to zero and allowing time to recover thristor junctions
D) none of (A), (B) and (C)
Ans: C
73) The property of materials by which they can be drawn into wires is known as:
A) malleability
B) elasticity
C) creep
D) ductility
Ans: D
74) Full load cupper loss in a transformer is 1600 watts. At half load the cupper loss will be:
A) 6400 watt
B) 1600 watt
C) 800 watt
D) 400 watt
Ans: D
75) Which braking system on the locomotives is the costliest among the following?
A) Vacuum braking on diesel locomotives
B) Vacuum braking on steam locomotives
C) Regenerative braking on electric locomotives
D) All braking systems are equally costly
Ans: C
76) In a microprocessor, the address of the next instruction to be executed, is stored in
A) Stack pointer
B) Address latch
C) Program counter
D) General purpose register
Ans: C
77) A system is critically damped. If the gain of the system is increased, the system will behave as:
A) overdamped
B) underdamped
C) oscillatory
D) critically damped
Ans: B
78) An ideal voltage source will charge an ideal capacitor
A) in infinite time
B) exponentially
C) instantaneously
D) cannot be guessed
Ans: C
79) A long transmission line has considerable ……………….. effect.
A) series capacitance
B) shunt capacitance
C) series inductance
D) shunt inductance
Ans: B
80) For the protection of parallel feeders fed from one end, the relays used are:
A) non-directional relays at the source-end and directional relays at the load-end
B) non-directional relays at both the ends
C) directional relays at the source-end and non-directional at the load-end
D) directional relays at both the ends
Ans: A
81) The bridge used to measure the dielectric loss of an insulator is:
A) Anderson bridge
B) Wien’s bridge
C) Schering bridge
D) Any of the above
Ans: C
82) In a series RLC circuit at resonance, the magnitude of the voltage developed across the capacitor
A) is always zero
B) can never be greater than the input voltage
C) can be greater than the input voltage, however, it is 90° out of phase with the input voltage
D) can be greater than the input voltage, and is in phase with the input voltage.
Ans: C
83) A passive 2-port network is in a steady-state compared to its input, the steady state output can never offer
A) higher voltage
B) lower impedance
C) greater power
D) better regulation
Ans: C
84) The driving power from the prime-mover driving the alternator is lost but the alternator remains connected to the supply network; the field supply also remains on. The alternator will:
A) get burnt
B) behave as an induction motor but will rotate in the opposite direction
C) behave as a synchronous motor and will rotate in the same direction
D) behave as a synchronous motor but will rotate in a reverse direction to that corresponding to generator action
Ans: C
85) Impulse testing of transformers is done to determine the ability of:
A) bushings to withstand vibrations
B) insulation to withstand transient voltages
C) windings to withstand voltage fluctuations
D) all of the above
Ans: B
86) The melting point of carbon is:
A) 1800 degree Centigrade
B) 2200 degree Centigrade
C) 3500 degree Centigrade
D) 5500 degree Centigrade
Ans: C
87) A power system is subjected to a fault which makes the zero sequence component of current equal to zero. The nature of fault current is:
A) Double line to ground fault
B) Line to line fault
C) Line to ground fault
D) Three-phase to ground fault
Ans: B
A) twice the load impedance
B) complex conjugate of load impedance
C) twice the complex conjugate of load impedance
D) none of these
Ans: B
52) In power station practice “spinning reserve” is:
A) reserve generating capacity that is in operation but not in service
B) reserve generating capacity that is connected to bus and ready to take the load
C) reserve generating capacity that is available for service but not in operation
D) capacity of the part of the plant that remains under maintenance
Ans: B
53) Which of the following plants will take least time in starting from cold conditions to full-load operation?
A) Nuclear power plant
B) Steam power plant
C) Hydro-electric power plant
D) Gas turbine plant
Ans: C
54) Which of the following are the basic elements in a 555 timer IC?
(a) Two comparators
(b) A flip-flop
(c) A discharge transistor
(d) A resistive voltage divider
A) (a), (b) and (d)
B) only (a), (b) and (c)
C) only (b), (c) and (d)
D) only (a), (b), (c) and (d)
Ans: D
55) Which waveform out of the following waves has the least value of form-factor:
A) Triangular wave
B) Square wave
C) Rectangular wave
D) Sine wave
Ans: B
56) Which type of protection is provided on a generator to protect against stator insulation failure?
A) Differential protection
B) Overcurrent relay
C) Thermocouple actuated alarm
D) Reverse power relay
Ans: A
57) In an alternator if the winding is short pitched by 60 electrical degrees, its pitch factor will be:
A) 1.0
B) 0.866
C) 0.75
D) 0.50
Ans: B
58) The inertia constant of a 100 MVA, 11 kV water wheel generator is 4. The energy stored in the rotor at the synchronous speed is:
A) 400 Mega Joule
B) 400 Kilo Joule
C) 25 Mega Joule
D) 25 Kilo Joule
Ans: A
53) The reflection coefficient of a short-circuited line for voltage is:
A) -1
B) +1
C) 0.5
D) zero
Ans: A
54) The typical ratio of latching current to holding current in a 20A thyristor is
A) 5.0
B) 2.0
C) 1.0
D) 0.5
Ans: B
55) If the primary fault current is 2000 ampere, the relay setting current is 50 percent and the CT ratio is 400/5, then the plug-setting multiplier is:
A) 25
B) 15
C) 50
D) None of the above
Ans: D
56) Highest flux density exists inside which of the following instruments?
A) Electrodynamic instruments
B) Hot wire instruments
C) Moving iron instruments
D) Moving coil instruments
Ans: D
57) The current gain of emitter follower is:
A) less than one
B) more than one
C) zero
D) unpredictable
Ans: B
58) Which statement out of the following statements about ‘corona’ is incorrect?
A) Corona gives rise to radio interference
B) Corona results in loss of power in transmission
C) Corona discharge can be observed as red luminescence
D) Corona is always accompanied by a hissing voice
Ans: C
59) A three-phase transformer, connected in star-delta, is composed of three single-phase transformers, each rated 127/ 13.2 kV. The line-to-line voltage ratio for the three-phase transformer is:
A) 220 / 13.2 kV
B) 127 / 13.2 kV
C) 127 / 220 kV
D) 220 / 220 kV
Ans: A
60) Synchronous wattage of induction motor means:
A) rotor input in watts
B) stator input in watts
C) combined stator and rotor input in watts
D) shaft output in watts
Ans: A
61) The average power delivered to an impedance 4 − j 3 Ω by a current 5Cos(100πt + 100) Ampere is
A) 44.2 W
B) 50 W
C) 62.5 W
D) 125 W
Ans: B
62) Two 220 volt lamps, one of 60 watt and the other of 75 watt are connected in series across a 440 volt supply. The potential difference across 60 watt lamp will be:
A) 195 volt
B) 220 volt
C) 245 volt
D) 440 volt
Ans: C
63) The load-flow solution is always assured in case of:
A) Newon-Raphson method
B) Gauss-Seidal method
C) Fast Decoupled method
D) None of these methods guarantee
Ans: A
64) Full load current of an Induction motor is 20 Ampere. The no-load current may be expected to be:
A) 25 Ampere to 28 Ampere
B) 15 Ampere to 18 Ampere
C) 11 Ampere to 14 Ampere
D) 6 Ampere to 10 Ampere
Ans: D
65) Which of the following relation is incorrect?
A) capacity factor = utilization factor x load factor
B) load factor x maximum load = average load
C) demand factor x connected load = maximum demand
D) none of these
Ans: D
66) The inrush current of a transformer at no-load is maximum, if it is switched-on when the supply voltage is at:
A) zero voltage value
B) at peak voltage value
C) at half of the peak voltage value
D) at 0.866 of the peak voltage value
Ans: A
67) A DC reactor is connected in series with each pole of a converter station in order to:
A) prevent commutation failures in the inverter
B) supply reactive power to the converter
C) improve system stability
D) increase the power transfer capability
Ans: A
68) Two stator windings of AC servomotors are oriented:
A) 90 degree (mechanical) apart
B) 90 degree (electrical) apart
C) 180 degree (mechanical) apart
D) 180 degree (electrical) apart
Ans: B
69) A 10A DC Ammeter has a resistance of 0.1 Ω is to be extended to 50 A, the required shunt wire is
A) Manganin wire of 20 m Ω
B) Constantan wire of 20 m Ω
C) Manganin wire of 25 m Ω
D) Constantan wire of 25 m Ω
Ans: C
70) Two single-phase 150 kVA, 7200/ 600 volt transformers are connected in open-delta. The maximum three-phase load that they can carry is:
A) 300 kVA
B) 75 kVA
C) 259 kVA
D) 249 kVA
Ans: C
71) A DC Motor develops a torque of 150 N-m. A 10 percent reduction in the field flux causes a 50 percent increase in armature current. The new value of torque is:
A) 102.5 N-m
B) 202.5 N-m
C) 172.5 N-m
D) 232.5 N-m
Ans: B
72) Natural commutation means:
A) reducing the thyristor current to zero
B) reducing the thyristor current below “holding current”
C) reducing the current to zero and allowing time to recover thristor junctions
D) none of (A), (B) and (C)
Ans: C
73) The property of materials by which they can be drawn into wires is known as:
A) malleability
B) elasticity
C) creep
D) ductility
Ans: D
74) Full load cupper loss in a transformer is 1600 watts. At half load the cupper loss will be:
A) 6400 watt
B) 1600 watt
C) 800 watt
D) 400 watt
Ans: D
75) Which braking system on the locomotives is the costliest among the following?
A) Vacuum braking on diesel locomotives
B) Vacuum braking on steam locomotives
C) Regenerative braking on electric locomotives
D) All braking systems are equally costly
Ans: C
76) In a microprocessor, the address of the next instruction to be executed, is stored in
A) Stack pointer
B) Address latch
C) Program counter
D) General purpose register
Ans: C
77) A system is critically damped. If the gain of the system is increased, the system will behave as:
A) overdamped
B) underdamped
C) oscillatory
D) critically damped
Ans: B
78) An ideal voltage source will charge an ideal capacitor
A) in infinite time
B) exponentially
C) instantaneously
D) cannot be guessed
Ans: C
79) A long transmission line has considerable ……………….. effect.
A) series capacitance
B) shunt capacitance
C) series inductance
D) shunt inductance
Ans: B
80) For the protection of parallel feeders fed from one end, the relays used are:
A) non-directional relays at the source-end and directional relays at the load-end
B) non-directional relays at both the ends
C) directional relays at the source-end and non-directional at the load-end
D) directional relays at both the ends
Ans: A
81) The bridge used to measure the dielectric loss of an insulator is:
A) Anderson bridge
B) Wien’s bridge
C) Schering bridge
D) Any of the above
Ans: C
82) In a series RLC circuit at resonance, the magnitude of the voltage developed across the capacitor
A) is always zero
B) can never be greater than the input voltage
C) can be greater than the input voltage, however, it is 90° out of phase with the input voltage
D) can be greater than the input voltage, and is in phase with the input voltage.
Ans: C
83) A passive 2-port network is in a steady-state compared to its input, the steady state output can never offer
A) higher voltage
B) lower impedance
C) greater power
D) better regulation
Ans: C
84) The driving power from the prime-mover driving the alternator is lost but the alternator remains connected to the supply network; the field supply also remains on. The alternator will:
A) get burnt
B) behave as an induction motor but will rotate in the opposite direction
C) behave as a synchronous motor and will rotate in the same direction
D) behave as a synchronous motor but will rotate in a reverse direction to that corresponding to generator action
Ans: C
85) Impulse testing of transformers is done to determine the ability of:
A) bushings to withstand vibrations
B) insulation to withstand transient voltages
C) windings to withstand voltage fluctuations
D) all of the above
Ans: B
86) The melting point of carbon is:
A) 1800 degree Centigrade
B) 2200 degree Centigrade
C) 3500 degree Centigrade
D) 5500 degree Centigrade
Ans: C
87) A power system is subjected to a fault which makes the zero sequence component of current equal to zero. The nature of fault current is:
A) Double line to ground fault
B) Line to line fault
C) Line to ground fault
D) Three-phase to ground fault
Ans: B
88. The device that exhibits negative resistance region is
(A) Diac (B) Triac
(C) UJT (D) Transistor
Ans: C
89. Tensile strength of steel is improved by adding
(A) Nickel (B) Chromium
(C) Silicon (D) Lead
Ans: B
90. Modulus of elasticity is defined as the ratio of
(A) shear stress to shear strain
(B) linear stress to linear strain
(C) linear strain to lateral strain
(D) lateral strain to linear strain
Ans: B
91. Modulus of Elasticity (E) is defined as
(A) tensile stress/ tensile strain
(B) tensile strain/ tensile stress
(C) tensile stress x tensile strain
(D)transverse strain/ tensile strain
Ans: A
92. A shaft is subjected to-----kind of loads.
(A) Torsional only
(B) Bending and Torsional only
(C) Axial and Torsional only
(D) Combination of Torsional, Bending and Axial
Ans: D
93. Selection of fuse wire
(A) maximum current rating of the circuit
(B) maximum power rating
(C) maximum voltage rating
(D) transient current
Ans: A
94. The engine which uses constant pressure cycle is
(A) four stroke petrol engine
(B) four stroke diesel engine
(C) two stroke petrol engine
(D) two stroke diesel engine
Ans: B
95. The fractional slip of an induction motor is the ratio of
(A) Rotor cu. loss/Rotor input
(B) Stator cu. loss/Stator input
(C) Rotor cu. loss/Rotor output
(D) Rotor cu. loss/Stator cu. loss
Ans: D
96. The other name for voltage variable capacitance diode is
(A) PIN Diode (B) Tunnel Diode
(C) Zener Diode (D) Varactor Diode
Ans: D
97. Which of the following DC generator cannot build up on no load or open circuit?
(A) shunt (B) series
(C) short shunt (D) long shunt
Ans: B
98. _________is a fixed frequency oscillator.
(A) Phase-shift oscillators
(B) Hartley oscillator
(C) Colpitt's oscillator
(D) Crystal oscillator
Ans: D
99. The Speed-Time curve for city service has no ___________period.
(A) coasting (B) free running
(C) acceleration (D) braking
Ans: B
100. A DC motor having full load speed of 750 rpm and speed regulation of 10 % will have no load speed of
(A) 675 rpm
(C) 800 rpm
(B) 700 rpm
(D) 825 rpm
Ans: D
(A) Diac (B) Triac
(C) UJT (D) Transistor
Ans: C
89. Tensile strength of steel is improved by adding
(A) Nickel (B) Chromium
(C) Silicon (D) Lead
Ans: B
90. Modulus of elasticity is defined as the ratio of
(A) shear stress to shear strain
(B) linear stress to linear strain
(C) linear strain to lateral strain
(D) lateral strain to linear strain
Ans: B
91. Modulus of Elasticity (E) is defined as
(A) tensile stress/ tensile strain
(B) tensile strain/ tensile stress
(C) tensile stress x tensile strain
(D)transverse strain/ tensile strain
Ans: A
92. A shaft is subjected to-----kind of loads.
(A) Torsional only
(B) Bending and Torsional only
(C) Axial and Torsional only
(D) Combination of Torsional, Bending and Axial
Ans: D
93. Selection of fuse wire
(A) maximum current rating of the circuit
(B) maximum power rating
(C) maximum voltage rating
(D) transient current
Ans: A
94. The engine which uses constant pressure cycle is
(A) four stroke petrol engine
(B) four stroke diesel engine
(C) two stroke petrol engine
(D) two stroke diesel engine
Ans: B
95. The fractional slip of an induction motor is the ratio of
(A) Rotor cu. loss/Rotor input
(B) Stator cu. loss/Stator input
(C) Rotor cu. loss/Rotor output
(D) Rotor cu. loss/Stator cu. loss
Ans: D
96. The other name for voltage variable capacitance diode is
(A) PIN Diode (B) Tunnel Diode
(C) Zener Diode (D) Varactor Diode
Ans: D
97. Which of the following DC generator cannot build up on no load or open circuit?
(A) shunt (B) series
(C) short shunt (D) long shunt
Ans: B
98. _________is a fixed frequency oscillator.
(A) Phase-shift oscillators
(B) Hartley oscillator
(C) Colpitt's oscillator
(D) Crystal oscillator
Ans: D
99. The Speed-Time curve for city service has no ___________period.
(A) coasting (B) free running
(C) acceleration (D) braking
Ans: B
100. A DC motor having full load speed of 750 rpm and speed regulation of 10 % will have no load speed of
(A) 675 rpm
(C) 800 rpm
(B) 700 rpm
(D) 825 rpm
Ans: D
- UPSC Exam Syllabus- Electrical Engineering
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