electrical engineering test questions
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Electrical Engineering Technical Test Questions
1. Consider the following statements:
1. Reduce fault level
2. Improve stability of the system
3. Achieve asynchronous operation
Among these statements:
(a) 1 and 2 are correct
(b) 2 and 3 are correct
(c) 1 and 3 are correct
(d) 1, 2 and 3 are correct
Ans:-B
2. Consider the following statements regarding stability analysis by Routh-Hurwitz criterion:
1. For a system to be stable, all the coefficients of the characteristic equation must be present and be of the same sign.
2. If a system is to be stable, there should not be any sign change in the first column of the Routh‘s array.
3. The order of the auxiliary equation obtained from the elements of the Routh‘s table is always odd.
Of these statements:
(a) 1 and 2 are correct
(b) 2 and 3 are correct
(c) 1 and 3 are correct
(d) 1, 2 and 3 are correct
Ans:-A
3. A synchro transmitter-control transformer pair is excited at 400 Hz ac voltage. The output voltage
(a) has constant magnitude but its phase angle is proportional to the angular difference between their rotor angles
(b) Has a magnitude proportional to the sine of the angular difference between their rotors with its phase angle changing by 180° whenever the sign of the angular difference changes
(c) Has both magnitude and phase angle proportional to the angular difference between their rotors
(d) Has constant magnitude but its phase angle changes by 180° whenever the sign of the angular difference changes
Ans:-B
4. To ensure that a two-phase induction type servomotor does not run when the control phase voltage is zero, the ratio of
(a) Stator leakage reactance to rotor phase resistance should be high
(b) Rotor leakage reactance to rotor phase resistance should be less than one
(c) The sum of stator and rotor resistances to the sum of stator and rotor leakage reactances should be greater than one
(d) Torque to inertia should be very high
Ans:-B
5. A 1000/5 A bar primary current transformer has the ratio and phase errors at its rated current with a certain secondary burden of — 0.24 per cent and +30 minutes respectively. If the number of secondary turns is reduced by unity, the new ratio error and phase error at the rated current and for the same burden will be respectively
(a) —0.24 per cent and + 30 minutes
(b) + 0.26 per cent and + 30 minutes
(c) + 0.24 per cent and — 30 minutes
(d) zero and + 30 minutes
Ans:-A
Directions: The following items consist of two statements, one labelled the “Assertion A” and the other labelled the ‘Reason R’. You are to examine these two statements carefully and decide f the Assertion A and the Reason R are individually true and f so, whether the Reason is a correct explanation of the Assertion. Select your answers to these items using the codes given below and mark your answer sheet accordingly.
Codes:
(a) Both A and R are true and R is the correct explanation of A
(b) both A and R are true but R Is NOT a correct explanation of A
(c) A is true but R is false
(d) A is false but R is true
6. Assertion (A): The generated voltage in three- phase supply contains harmonics.
Reason (R): The angular variation of the radial component of the magnetic flux in the air-gap is not a pure sinusoid.
Ans:-A
7. Assertion (A): The driving-point impedance and the driving-point admittance are reciprocals of each-other.
Reason (R) : The driving-point network functions are the ratios of Laplace transforms of appropriate quantities (voltage and current) at the same pair of terminals.
Ans:-A
8. Assertion (A): In the case of wave-type winding in a dc machine of more than two poles, two brushes may be just enough for communication, but the normal practice is to use as any brushes as there are poles in the machine.
Reason (R): On using more than two brushes in a 4-pole machine, the number of coils in series undergoing communication becomes half and so also the emf of self-induction in the commutated coils.
Ans:-C
9. The economizer, a component of steam power plants, is a heat-exchanger utilizing the waste heat of
(a) bleed-steam to heat the feed water
(b) flue-gas to heat the feed water
(c) flue-gas to heat the air going into the boiler
(d) flue-gas to heat the pulverised coal
Ans:-B
10. Consider the following statements about the utility of delta-connected tertiary windings in star-star connected power transformer:
1. It makes supply available for small loads.
2. It provides low reactance paths for zero sequence currents.
3. It is used to suppress harmonic voltages.
4. It is used to allow flow of earth fault current for operation of protective relays.
Which of these statements are correct?
(a) 1 and 2
(b) 2, 3 and 4
(c) 1, 3 and 4
(d) 1, 2, 3 and 4
Ans:-D
11. A 3-phase transmission line conductors were arranged in horizontal spacing, with ‘d’ as the distance between adjacent conductors. If these conductors are rearranged to form an equilateral triangle with sides equal to‘d’, then the
(a) capacitance and the inductance will increase
(b) capacitance will increase and the inductance will decrease
(c) capacitance and the inductance will remain the same
(d) capacitance will decrease and the inductance will increase
Ans:-B
12. The Inductance per unit length of an overhead line due to internal flux linkages
(a) depends on the size of the conductor
(b) is independent of the size of conductor and constant
(c) depends on the current through the conductor
(d) depends on distance between conductors
Ans:-B
13. A synchronous generator with a synchronous reactance of 1.3 Pu is connected to an infinite bus whose voltage is I pu, through an equivalent reactance of 0.2pu. For maximum output of 1.2 pu, the alternator emf must be
(a) 1.5pu
(b) 1.56pu
(c) 1.8 pu
(d) 2.5pu
Ans:-A
14. Consider the following statements:
Transient stability of a synchronous generator feeding power to an Infinite bus through a transmission line can be increased by
1. increasing the steam supply to the turbine driving the generator during fault clearing.
2. connecting resistors at the generator terminals during fault conditions.
3. employing a faster excitation system.
4. quickly throwing off the generator load.
Which of these statements are correct?
(a) 2 and 3
(b) 3 and 4
(c) l and 2
(d) 2 and 4
Ans:-D
15. An overhead transmission line having surge impedance ‘Z1 ‘is terminated to an underg1ound cable of surge impedance ‘Z2’ The reflection coefficient for the travelling wave at the junction of the line and cable is
(a) ZI +Z2 / Z1 -Z2
(b) Z2 / Z1 + Z2
(c) Z2 – Z1 / Z1 +Z2
(d) Z1 – Z2 / Z1 +Z2
Ans:-C
16. Ring main distribution is preferred to a radial system because
(a) voltage drop in the feeder is less and supply is more reliable
(b) voltage-drop in the feeder is less and power factor is high
(c) power factor is high and supply is more reliable’
(d) power factor is high and system is less expensive
Ans:-A
17. If the fault current is 3000 A for a relay with a plug setting of 50% and CT ratio of 1000:1, the plug setting multiplier would be
(a) 1.5
(b) 3
(c) 4.5
(d) 6
Ans:-D
18. Match List I (Protective schemes) with List II (Equipment) and select the correct answer using the codes given the Lists:
List I
A. Mho relays
B. Inverse time over current relays
C. Differential relays
List II
1. Generators
2. Transmission lines
3. Motors
Codes:
A B C
(a) 2 1 3
(b) 2 3 1
(c) 3 2 1
(d) 1 3 2
Ans:-C
19. Reversal of power flow In HVDC link by controlling the firing angle simultaneously at both the converter stations results in
(a) reversal of voltage polarity of HVDC pole
(b) reversal of current in dc link
(c) reversal of current in dc link as well as reversal of voltage polarity of HVDC pole
(d) neither reversal of current in dc link nor reversal of voltage polarity of HVDC
Ans:-B
20. In a loaded dc generator, if the brushes are given a shift from the interpolar axis in the direction of rotation, then the commutation will
(a) improve with fall of terminal voltage
(b) deteriorate with fall of terminal voltage
(c) improve with rise in terminal voltage
(d) deteriorate with rise in terminal voltage
Ans:-B
21. A dc shunt motor is required to drive a constant power load at rated speed while drawing rated armature current. Neglecting saturation and all machine losses, f both the terminal voltage and the field current of the machine are halved, then
(a) the speed becomes 2 pu (per unit) but armature current remains at 1 Pu
(b) the speed remains at 1 Pu but armature current becomes 2 Pu
(c) both speed and armature current becomes 2 Pu
(d) both speed and armature current remain at 1 pu
Ans:-B
22. A 3-phase synchronous motor with negligible losses is connected to the supply at rated frequency and constant terminal voltage ‘V’ The induced emf of the motor is designated as E. If the motor is now gradually loaded to its rated power, adjusting its excitation to obtain, say 0.8 leading power factor operations, then E-phasor would
(a) be less than V-phasor and also lead V-phasor
(b) be greater than V-phasor and also lead V-phasor
(c) be less than V-phasor and also lag V-phasor
(d) be greater than V-phasor and also lag V- phasor
Ans:-A
23. An alternator of 400 kW is driven by a prime mover of speed regulation 4% and another alternator of 200 km is driven by a prime mover of speed regulation 3%. The total load they can machines is
(a) 600 kW
(b) 500 kW
(c) 450 kW
(d) 400 kW
Ans:-C
24. Consider the following statements:
Modern alternators are designed for large air- gap to have
1. large inherent regulation.
2. very stable parallel operation.
3. higher stability limit
4. sinusoidal mmf distribution.
Which of these statements are correct?
(a) 1, 2 and 3
(b) 2, 3 and 4
(c) 1, 3 and 4
(d) 1, 2 and 4
Ans:-B
25. When a single-phase capacitor start induction motor is running at a steady speed delivering a fixed torque, then
(a) peak of forward rotor mmf is equal to the peak of backward rotor mmf
(b) peak of forward stator mmf is equal to the peak of backward stator mmf
(c) net forward rotating flux is equal to the net backward rotating flux
(d) forward flux produced by rotor current is equal to backward flux produced by rotor current
Ans:-C
Showing posts with label Electrical. Show all posts
Showing posts with label Electrical. Show all posts
Thursday, September 1, 2011
paper Electrical engineering BHEL
paper Electrical engineering BHEL
Sample Solved Questions objective type
BHEL supervisor trainee model question paper
1. Consider the following situations / conditions for a phase-controlled convener:
1. Firing angle is varied hi the range of 900 to 180°.
2. Firing angle is varied in the range of zero to 90°.
3. feeds a load compring RL and additional back emf lead.
4. Feeds a load comprising RL and additional dc voltage source.
A phase-controlled converter will operate as an inverter only when
(a) 1 and 3 are simultaneously satisfied
(b) 2 and 4 simultaneously satisfied
(c) 2 and 3 are simultaneously satisfied
(d) 1 and 4 are simultaneously satisfied.
Ans:-D
2. A dc chopper has a resistive load of 10 ohms and an input voltage of 220 V. When the chopper switch is ‘ON’, its voltage drop is 2V and the chopping frequency is I kHz. If the duty cycle is 50%, then the average output voltage will be
(a) 100V
(b) l03V
(c) 106V
(d) 109V
Ans:-D
3. A voltage control bus is characterised by the specified values of
(a) real and reactive powes
(b) real power and voltage phase angle
(c) real power and voltage magnitude
(d) reactive power and voltage magnitude
Ans:-C
4. A system is said to be effectively grounded only if R0 / X1 and X0 / X1 are respectively (symbols have the usual meanings)
(a) greater than or equal to 1 and less than or equal to 3
(b) less than or equal to 1 and greater than or equal to 3
(c) greater than or equal to 2 and less than or equal to 2
(d) less than or equal to 2 and greater than or equal to 2
Ans:-A
5. Match List I (Coils of a harmonic restrained percentage bias differential relay used for power transformer protection) with List II (Currents flowing through the relay coil) and select the correct answer using the codes given below the lists:
List I
A. Operating coil
B. Restraining coil
C. Bias coil
List II
1. Through current
2. Differential current
3. Second harmonic current
Codes:
A B C
(a) 1 3 2
(b) 2 3 1
(c) 3 2 1
(d) 2 1 3
Ans:-B
6. A composite transmission and distribution network has lines working at different voltages Match List I (Voltage level used) with List II (Type of relays used for protection) and select the correct answer using the codes given below the lists
List I
A. 220kV
B. 33kV
C. 11kV
List II
1. Directional time lag over current relays
2. Carrier current relays
3. Distance relays
Codes:
A B C
(a) 1 3 2
(b) 3 2 1
(c) 2 1 3
(d) 2 3 1
Ans:-B
7. Consider the following statements:
A differential relay is used for a 3-phase transformer protection to avoid maloperation
due to
1. saturation of current transformer.
2. mismatching of the current ratio for current transformers.
3. difference in connections on both sides of power transformer.
4. current setting multipliers.
Of these statements:
(a) 1 and 4 are correct
(b) 1 and 2 are correct
(c) 1, 2 and 3 are correct
(d) 2, 3 and 4 are correct
Ans:-C
8. 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:-C
9. The power transmission capability of bipolar lines is approximately
(a) half that of 3-phase single circuit line
(b) the same as that of 3-phase single circuit line
(c) twice that of 3-phase single circuit line
(d) thrice that of 3-phase single circuit line
Ans:-B
Directions: The following ten items consist of two statements, one labelled, the ‘Assertion A’ and the other labelled the ‘Reason R’. You are to examine these two statements carefully and decide if the Assertion A and the Reason Rare individually true
and if so, whether the Reason is a correct explanation of the Assertion. Select your answers to these items using the codes given below and mark your answer sheet accordingly.
Codes:
(a) Both A and R is true and R Is the correct explanation of A
(b) Both A and R is true but R is not a correct explanation A
(c) A is true but R is false
(d) A Is false but R Is true
10. Assertion (A): The steady-state error due to step input to a system represented by G(s) = 10 (1+ 0.5s) / s(1+s)(1+2s) is zero.
Reason (R) : For a type 1 system, the steady- state error due to step input is zero.
Ans:-A
11. Assertion (A) : In an error detector using a synchro transmitter and a synchrocontrol transformer, the later is connected to the servo amplifier.
Reason (R) : The synchro transmitter is a salient pole device and the control transformer had a low reluctance rotor.
Ans:-A
12. Assertion (A) : Vertical deflection sensitivity of a CRO is higher than that of the horizontal system.
Reason (R) : Sweep voltage is applied to the horizontal deflecting plates.
Ans:-A
13. Assertion (A) : In a class B push-pull power amplifier, there is no power loss under no signal condition.
Reason (R) : The two transistors are biased at cut-off.
Ans:-A
14. Assertion (A): Some compromise is necessary while selecting the value of commutating capacitors of a bistable multivibrator.
Reason (R) : Smaller commutating capacitors yield shorter transition time and longer setting time.
Ans:-B
15. Assertion (A) : For TV transmission, microwave links are preferred over coaxial cables.
Reason (R) Microwave links have greater bandwidth.
Ans:-B
16. Assertion (A) : The no-load current of star/star connected bank of three single-phase transformers contains all harmonics except the triplen harmonics.
Reason (R): Saturation of the core is responsible for the harmonics in the no-load current of a single-phase transformer.
Ans:-B
17. Assertion (A): The inductive voltage drop caused at the terminals of an ac to dc converter at given value of local current does not depend upon the
firing angle.
Reason (R) : The overlap of conduction of incoming and outgoing thyristors is responsible for the inductive voltage drop.
Ans:-C
18. Assertion (A) : Time lag is invariably provided in the majority of protective relaying schemes for the protection of various elements of the electrical power system network.
Reason (R) : Time lag is provided to permit discrimination between main and back-up protection.
Ans:-B
19. Assertion (A) : Insulators should have high impulse ratio and lighning arrestors should have low impulse ratio.
Reason (R): Lightning arrestors are required to divert surge currents to the ground.
Ans:-A
20. For an ac circuit, if e(t) = 160 sin (wt + 10° and i(t) = 5sin (wt — 200), then the reactive power absorbed by the circuit will be
(a) 400 Vars
(b) 346.4 Vars
(c) 200 Vars
(d) 136.8 Vars
Ans:-B
21. For a two-port network, match List I with List II and select the correct answer using the codes given below the lists:
List I
(Impedance Function)
A. z11
B.z22
C. z12
D.z21
List II
(Equivalent transmission coefficient)
1. D/C
2. A/C
3. I/C
4. Delta T/C
Codes:
A B C D
(a) 2 1 4 3
(b) 1 2 3 4
(c) 2 1 3 4
(d) 1 2 4 3
Ans:-A
22. The effect of phase-lead compensator on gain cross-over frequency Wcg and the bandwidth W b is that
(a) Both increase
(b) Both decrease
(c) W cg increase while W b decreases
(d) W cg decreases while W b increases
Ans:-A
23. If R and X are the resistance and inductive reactance respectively, D and L are the diameter and length respectively of the rotor of a two- phase ac servomotor, then the ratios D/L and X / R will be respectively
(a) Large and large
(b) Large and small
(c) Small and large
(d) Small and small
Ans:-D
24. In the case of an armature controlled dc motor, f the equivalent moment of inertia of the motor and load is made small and the armature resistance is reduced, then the motor tends to act like
(a) A differentiating circuit
(b) An integrating circuit
(c) A PID controller
(d) A second order critically damped system
Ans:-D
25. A dc shunt generator is running at rated speed developing its rated voltage. Match List-I (condition of operation) with List-II (effect) and select the correct answer using the codes given below the lists:
List-I
A. The direction of rotation, residual magnetism and field connections are reversed.
B. The direction of residual magnetism and field connections are reversed.
C. The direction of rotation and connection of the field winding are reversed.
D. The direction of rotation and residual magnetism are reversed
List-II
1. The generator will build up with same polarity.
2. The generator will build up with reversed polarity.
3. The generator will not build up.
Codes:
A B C D
(a) 1 3 2 2
(b) 3 2 1 2
(c) 3 2 2 1
(d) 2 3 1 1
Ans:-B
Sample Solved Questions objective type
BHEL supervisor trainee model question paper
1. Consider the following situations / conditions for a phase-controlled convener:
1. Firing angle is varied hi the range of 900 to 180°.
2. Firing angle is varied in the range of zero to 90°.
3. feeds a load compring RL and additional back emf lead.
4. Feeds a load comprising RL and additional dc voltage source.
A phase-controlled converter will operate as an inverter only when
(a) 1 and 3 are simultaneously satisfied
(b) 2 and 4 simultaneously satisfied
(c) 2 and 3 are simultaneously satisfied
(d) 1 and 4 are simultaneously satisfied.
Ans:-D
2. A dc chopper has a resistive load of 10 ohms and an input voltage of 220 V. When the chopper switch is ‘ON’, its voltage drop is 2V and the chopping frequency is I kHz. If the duty cycle is 50%, then the average output voltage will be
(a) 100V
(b) l03V
(c) 106V
(d) 109V
Ans:-D
3. A voltage control bus is characterised by the specified values of
(a) real and reactive powes
(b) real power and voltage phase angle
(c) real power and voltage magnitude
(d) reactive power and voltage magnitude
Ans:-C
4. A system is said to be effectively grounded only if R0 / X1 and X0 / X1 are respectively (symbols have the usual meanings)
(a) greater than or equal to 1 and less than or equal to 3
(b) less than or equal to 1 and greater than or equal to 3
(c) greater than or equal to 2 and less than or equal to 2
(d) less than or equal to 2 and greater than or equal to 2
Ans:-A
5. Match List I (Coils of a harmonic restrained percentage bias differential relay used for power transformer protection) with List II (Currents flowing through the relay coil) and select the correct answer using the codes given below the lists:
List I
A. Operating coil
B. Restraining coil
C. Bias coil
List II
1. Through current
2. Differential current
3. Second harmonic current
Codes:
A B C
(a) 1 3 2
(b) 2 3 1
(c) 3 2 1
(d) 2 1 3
Ans:-B
6. A composite transmission and distribution network has lines working at different voltages Match List I (Voltage level used) with List II (Type of relays used for protection) and select the correct answer using the codes given below the lists
List I
A. 220kV
B. 33kV
C. 11kV
List II
1. Directional time lag over current relays
2. Carrier current relays
3. Distance relays
Codes:
A B C
(a) 1 3 2
(b) 3 2 1
(c) 2 1 3
(d) 2 3 1
Ans:-B
7. Consider the following statements:
A differential relay is used for a 3-phase transformer protection to avoid maloperation
due to
1. saturation of current transformer.
2. mismatching of the current ratio for current transformers.
3. difference in connections on both sides of power transformer.
4. current setting multipliers.
Of these statements:
(a) 1 and 4 are correct
(b) 1 and 2 are correct
(c) 1, 2 and 3 are correct
(d) 2, 3 and 4 are correct
Ans:-C
8. 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:-C
9. The power transmission capability of bipolar lines is approximately
(a) half that of 3-phase single circuit line
(b) the same as that of 3-phase single circuit line
(c) twice that of 3-phase single circuit line
(d) thrice that of 3-phase single circuit line
Ans:-B
Directions: The following ten items consist of two statements, one labelled, the ‘Assertion A’ and the other labelled the ‘Reason R’. You are to examine these two statements carefully and decide if the Assertion A and the Reason Rare individually true
and if so, whether the Reason is a correct explanation of the Assertion. Select your answers to these items using the codes given below and mark your answer sheet accordingly.
Codes:
(a) Both A and R is true and R Is the correct explanation of A
(b) Both A and R is true but R is not a correct explanation A
(c) A is true but R is false
(d) A Is false but R Is true
10. Assertion (A): The steady-state error due to step input to a system represented by G(s) = 10 (1+ 0.5s) / s(1+s)(1+2s) is zero.
Reason (R) : For a type 1 system, the steady- state error due to step input is zero.
Ans:-A
11. Assertion (A) : In an error detector using a synchro transmitter and a synchrocontrol transformer, the later is connected to the servo amplifier.
Reason (R) : The synchro transmitter is a salient pole device and the control transformer had a low reluctance rotor.
Ans:-A
12. Assertion (A) : Vertical deflection sensitivity of a CRO is higher than that of the horizontal system.
Reason (R) : Sweep voltage is applied to the horizontal deflecting plates.
Ans:-A
13. Assertion (A) : In a class B push-pull power amplifier, there is no power loss under no signal condition.
Reason (R) : The two transistors are biased at cut-off.
Ans:-A
14. Assertion (A): Some compromise is necessary while selecting the value of commutating capacitors of a bistable multivibrator.
Reason (R) : Smaller commutating capacitors yield shorter transition time and longer setting time.
Ans:-B
15. Assertion (A) : For TV transmission, microwave links are preferred over coaxial cables.
Reason (R) Microwave links have greater bandwidth.
Ans:-B
16. Assertion (A) : The no-load current of star/star connected bank of three single-phase transformers contains all harmonics except the triplen harmonics.
Reason (R): Saturation of the core is responsible for the harmonics in the no-load current of a single-phase transformer.
Ans:-B
17. Assertion (A): The inductive voltage drop caused at the terminals of an ac to dc converter at given value of local current does not depend upon the
firing angle.
Reason (R) : The overlap of conduction of incoming and outgoing thyristors is responsible for the inductive voltage drop.
Ans:-C
18. Assertion (A) : Time lag is invariably provided in the majority of protective relaying schemes for the protection of various elements of the electrical power system network.
Reason (R) : Time lag is provided to permit discrimination between main and back-up protection.
Ans:-B
19. Assertion (A) : Insulators should have high impulse ratio and lighning arrestors should have low impulse ratio.
Reason (R): Lightning arrestors are required to divert surge currents to the ground.
Ans:-A
20. For an ac circuit, if e(t) = 160 sin (wt + 10° and i(t) = 5sin (wt — 200), then the reactive power absorbed by the circuit will be
(a) 400 Vars
(b) 346.4 Vars
(c) 200 Vars
(d) 136.8 Vars
Ans:-B
21. For a two-port network, match List I with List II and select the correct answer using the codes given below the lists:
List I
(Impedance Function)
A. z11
B.z22
C. z12
D.z21
List II
(Equivalent transmission coefficient)
1. D/C
2. A/C
3. I/C
4. Delta T/C
Codes:
A B C D
(a) 2 1 4 3
(b) 1 2 3 4
(c) 2 1 3 4
(d) 1 2 4 3
Ans:-A
22. The effect of phase-lead compensator on gain cross-over frequency Wcg and the bandwidth W b is that
(a) Both increase
(b) Both decrease
(c) W cg increase while W b decreases
(d) W cg decreases while W b increases
Ans:-A
23. If R and X are the resistance and inductive reactance respectively, D and L are the diameter and length respectively of the rotor of a two- phase ac servomotor, then the ratios D/L and X / R will be respectively
(a) Large and large
(b) Large and small
(c) Small and large
(d) Small and small
Ans:-D
24. In the case of an armature controlled dc motor, f the equivalent moment of inertia of the motor and load is made small and the armature resistance is reduced, then the motor tends to act like
(a) A differentiating circuit
(b) An integrating circuit
(c) A PID controller
(d) A second order critically damped system
Ans:-D
25. A dc shunt generator is running at rated speed developing its rated voltage. Match List-I (condition of operation) with List-II (effect) and select the correct answer using the codes given below the lists:
List-I
A. The direction of rotation, residual magnetism and field connections are reversed.
B. The direction of residual magnetism and field connections are reversed.
C. The direction of rotation and connection of the field winding are reversed.
D. The direction of rotation and residual magnetism are reversed
List-II
1. The generator will build up with same polarity.
2. The generator will build up with reversed polarity.
3. The generator will not build up.
Codes:
A B C D
(a) 1 3 2 2
(b) 3 2 1 2
(c) 3 2 2 1
(d) 2 3 1 1
Ans:-B
Electrical Engineering BHEL PDF Book
Electrical Engineering BHEL PDF Book
Free Electrical Engineering book conataining objective type MCQ question for BHEL Engineer jobs Exam.
Multiple choice Question fully solved on Electrical Engg
Guide To Bhel Engineer Trainees Electrical Engineering
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Free Electrical Engineering book conataining objective type MCQ question for BHEL Engineer jobs Exam.
Multiple choice Question fully solved on Electrical Engg
Guide To Bhel Engineer Trainees Electrical Engineering
Free Download this book
Guide To Bhel Engineer Trainees Electrical Engineering
Electrical Engineering questions For PSU jobs
Electrical Engineering questions For PSU jobs
Solved Electrical Engineering for Career as Electrical engineering freshers in PSUs
Free CElectrical Engineering Sample Paper For PSU Jobs like SAIL BHEL IOC
1. A single line to ground fault occurs on a three- phase isolated neutral system with a line to neutral voltage of V kV. The potentials on the healthy phases rise to a value equal to
(a) √2 V k V
(b) √3 V kV
(c) 3 V kV
(d) 1/ √3VkV
Ans:-D
2. A one kilometer long 11 k V 3-core three-phase metal sheathed cable gave the following test results:
(i) Capacitance between 2 conductors joined to sheath and the third conductor: 0.6 µ F
(ii) Capacitance between all the three conductors bunched together and sheat: 0.96 µF
The effective capacitance of each core to neutral is
(a) 0.l2µF
(b) 0.14µF
(c) 0.16 µF
(d) 0.32 µ F
Ans:-B
3. If the current is 3000 A, for an I.D.M. T. relay with a plug setting of 50% and C. T. ratio of 400 / 5, the plug setting multiplier would be
(a) 7.5
(b) 15.0
(c) 18.75
(d) 37.5
Ans:-B
4. A balanced star-connected load with impedances. of 20 —30 Ohm is supplied from a beta phase, 4-wire, 173 volt system, the voltages to neutral being 100 —90°, 100 30° and 100 150°
The current in the neutral wire is
(a) 5 A
(b) 8.65 A
(c) Zero
(d) 50 A
Ans:-D
5. Two coils in differential connection have self- inductance of 2 mH and 4 mH and a mutual inductance of 0.15 mH. The equivalent inductance of the combination is
(a) 5.7mH
(b) 5.85mH
(c) 6mH
(d) 6.l5mH
Ans:-A
6. Two wattmeters connected to measure the power in a 3-phase balanced delta connected load read W1= 12 kW and W2 = 15 kW respectively. If the same load is reconnected in star, then the wattmetets would read
(a) W1 = 8.66 kW, W2 = 6.93 kW
(b) W1 = 6.93 kW, W2 = 8.66 kW
(c) W1 = 5kW, W2 = 4kW
(d) W1= 4kW, W2 = 5kW
Ans:-C
7. When compared to a first-order low-pass filter, a second-order low-pass filter has
(a) Lower voltage gain
(b) Higher voltage gain
(c) Faster drop in filter response
(d) Higher cut-off frequency
Ans:-D
8. Match List I with List II and select the correct answer using the codes given below the lists:
List I
(Hybrid parameters)
A. h11
B. h22
C. g11
D. g22
List II
(Relation with immittance parameters)
1. 1 / Y11
2. 1 / Z 22
3. 1 / Z 11
4. 1 / Y 22
Codes:
A B C D
(a) 12 3 4
(b) 3 2 1 4
(c) 1 4 3 2
(d) 3 4 1 2
Ans:-B
9. To improve stability and time response of a control system, poles are often added to the system transfer function. In this context which
one of the following pairs is correctly matched?
(a) Zero poles ...make the system stable and slow responding
(b) One pole ... makes the system less stable and slow responding
(c) Two poles ...make the system less stable and fast responding
(d) Three poles ... make the system conditionally stable and fast responding
Ans:-C
10. Consider the following statements regarding root loci:
1. All root loci start from the respective poles of G(s) H(s).
2. All root loci end at the respective zeros of G(s) H(s) or go to infinity.
3. The root loci are symmetrical about the imaginary axis of the s-plane.
Of these statements:
(a) 1, 2 and 3 are correct
(b) 1 and 2 are correct
(c) 2 and 3 are correct
(d) 1 and 3 are correct
Ans:-B
11. Consider the following statements:
Addition of resistance to the rotor of a two-phase ac servomotor will
1. Increase the overall torque.
2. Increase the stability of operation.
3. Linearize its torque-speed characteristics.
4. Lead to attainment of maximum stalling torque
Of these statements:
(a) 1, 2 and 4 are correct
(b) 2, 3 and 4 are correct
(c) 2 and 3 are correct
(d) 1, 3 and 4 are correct
Ans:-C
12. A 6-pole lap-connected dc generator with 480 conductors has an armature resistance of 0.06 ohm. If the conductors are reconnected to form a wave winding, other things remaining unchanged, the value of the armature resistance will be
(a) 0.01 ohm
(b) 0.06 ohm
(c) 0.36 ohm
(d) 0.54 ohm
Ans:-D
13. A 2-pole series motor with its two field coils connected in series runs at a speed of 500 rpm. If the field coils ar reconnected in parallel and assuming that the torque is constant and the magnetic circuit is unsaturated, the new speed will be
(a) 250 rpm
(b) 500/ √2rpm
(c) 500 √rpm
(d) 1000 rpm
Ans:-D
14. Consider the following statements:
As a 3-phase induction motor is loaded from no- load to rated load,
1. there is an improvement in the power factor.
2. the torque increases almost in proportion to slip.
3. the air-gap flux falls sharply.
Of these statements:
(a) 1,2 and 3 are correct 4
(b) 1 and 2 are correct
(c) 2 and 3 are correct
(d) 1 and 3 are correct
Ans:-B
15. Short-circuit ratio of a synchronous machine is the ratio of the
(a) open-circuit voltage to the short-circuit current at a given excitation
(b) short-circuit current to the open-circuit voltage at a given excitation
(c) excitation current required for the rated voltage on open-circuit to the excitation current required for the rated armature current under short-circuit
(d) excitation current required for the rated
armature current under short-circuit to the excitation current required for rated voltage on open-circuit
Ans:-C
16. In a 3-phase induction motor, the angular speed of the stator field is ω and, the actual angular speed of the rotor is w r’, and the stator induced emf is given by es = NI, ω K ws Ø sin ωt, (N1 being the stator turns/phase), the rotor emf with N2 as the rotor/turns phase will be (K ws = stator winding factor and K wr =. rotor winding factor)
(a) e r = N2 ω K W r sin ω t
(b) e r =N2 ω r K wr sin ωr t
(c) e r = N2 (ω - ωr) Kωr Ø sin(ω —r)t
(d) e r = N2 ( ω+ ωr) K ωrØ sin (ω + ω r) t
Ans:-A
17. A 3-phase induction motor requires a starter
(a) because there is no back emf induced in the stator winding during starting
(b) because the motor does not possess an inherent starting torque
(c) because the induced secondary voltage and hence the currents in the windings are abnormally high during starting
(d) to increase the starting torque
Ans:-C
18. For a rotor-fed 3-phase induction motor, the absolute speed of the rotating magnetic field in space is
(a) the synchronous speed
(b) the difference between the synchronous speed and the rotor speed
(c) the rotor speed
(d) zero
Ans:-A
19. A synchronous machine connected to infinite bus bars is initially delivering active power to and absorbing lagging reactive power from the bus bars. As increase in the power input to the synchronous machine will cause
(a) an increase in both armature current and power factor
(b) an increase in armature current and a decrease in power factor
(c) a decrease in both armature current and power factor
(d) a decrease in armature current and an increase in power factor.
Ans:-A
20. The introduction of interpoles in between the main poles improves the performance of a dc machine, because
(a) the interpoles produce additional flux to augment the developed torque
(b) the flux waveform is improved with reduction in harmonics
(c) the inequality of air-gap flux on the top and bottom halves of the armature is removed
(d) a counter-emf is induced in the coil undergoing commutation
Ans:-C
21. For proper synchronisation of a large synchronous machine to a bus, the frequency of the-incoming machine
(a) should be exactly the same as that of the bus
(b) should be slightly higher than that of the bus
(c) should be slightly lower than that of the bus
(d) can be of any value
Ans:-B
22. A 3-phase alternator delivers power to a balanced 3-phase load of power factor 0.707 lagging. It is observed that the open-circuit emf phasor leads the corresponding terminal voltage phasor by 15°. Neglecting the effect of harmonies, the angle between the axis of the main field mmf and the axis of the armature mmf will be
(a) 300 electrical
(b) 60° electrical
(c) 90° electrical
(d) 150° electrical
Ans:-B
23. A 3-phase, 400 V, delta connected alternator has a synchronous impedance of (0+j20) ohms per phase. If it delivers a balanced load of 12 WA at zero power factor leading, then the percentage ‘voltage regulation of the alternator
is equal to
(a) —50
(b) +50
(c) —150
(d) +150
Ans:-C
24. If the height to width ratio of the window of core- type transformer is increased, then
(a) its leakage reactance and percentage voltage regulation will decrease
(b) its leakage reactance and percentage voltage regulation will increase
(c) its leakage reactance will be unaffected but total space in the window will increase to accommodate the windings better
(d) efficiency will increase and temperature rise will decrease
Ans:-A
25. A 220 / 110V, 50 Hz single-phase transformer having a negligible winding resistances operates from a variable voltage, variable frequency supply such that V I/f (V1 = primary applied voltage, f = source frequency) is constant. This will bring in, in the given range of frequencies,
(a) variation in both eddy current loss and hysteresis loss
(b) variation only in the eddy current loss, hysteresis loss remaining constant
(c) variation only in the hysteresis loss, eddy current loss remaining constant
(d) no change either in the eddy current loss or the hysteresis loss
Ans:-A
26. On direct on line (DOL) starting, dc motor is found to rotate in the direction opposite to that for which it was designed. The motor is a
(a) series motor
(b) shunt motor
(c) cumulatively compounded, motor
(d) differential compounded motor
Ans:-D
27. Consider the following statements:
To control the speed of a dc shunt motor above the base speed over a reasonably wide range, the motor must
1. have compensating winding
2. have interpole winding.
3. be started using a 3-point starter.
4. be started using a 4-point starter.
Of these statements:
(a) l, 2and 4arecorrect
(b) 1, 2 and 3 are correct
(c) 1 and 3 are correct
(d) 2 and 4 are correct
Ans:-A
28. Consider the following types of drives:
1. Slip energy recovery schemes with converter cascade in the rotor circuit.
2. Stator voltage control using ac voltage controller.
3. Constant V/f control (V = applied voltage, f = frequency).
4. Variable voltage and variable 7requency schemes with air-gap flux constant.
Those suitable for blowers and centrifugal pumps (T α N2) include
(a) l, 3and 4
(b) l, 2 and3
(c) l, 2 and 4
(d) 2, 3 and4
Ans:-B
29. In the case of a thyristor, di /dt capability can be improved by
(a) thermal triggering
(b) voltage triggering
(c) dV / dt triggering
(d) gate pulse triggering
Ans:-A
30. A 3-phase overhead transmission line has its conductors horizontally spaced with spacing between adjacent conductors equal to ‘d’ If, now, the conductors of the lines are rearranged to form an equilateral triangle of sides equal to ‘d’, then the
(a) average capacitance as well as average inductance will increase
(b) average capacitance will decrease but the average inductance will increase
(c) average capacitance will increase but the average inductance will decrease
(d) surge impedance loading of the lines will increase
Ans:-C
Solved Electrical Engineering for Career as Electrical engineering freshers in PSUs
Free CElectrical Engineering Sample Paper For PSU Jobs like SAIL BHEL IOC
1. A single line to ground fault occurs on a three- phase isolated neutral system with a line to neutral voltage of V kV. The potentials on the healthy phases rise to a value equal to
(a) √2 V k V
(b) √3 V kV
(c) 3 V kV
(d) 1/ √3VkV
Ans:-D
2. A one kilometer long 11 k V 3-core three-phase metal sheathed cable gave the following test results:
(i) Capacitance between 2 conductors joined to sheath and the third conductor: 0.6 µ F
(ii) Capacitance between all the three conductors bunched together and sheat: 0.96 µF
The effective capacitance of each core to neutral is
(a) 0.l2µF
(b) 0.14µF
(c) 0.16 µF
(d) 0.32 µ F
Ans:-B
3. If the current is 3000 A, for an I.D.M. T. relay with a plug setting of 50% and C. T. ratio of 400 / 5, the plug setting multiplier would be
(a) 7.5
(b) 15.0
(c) 18.75
(d) 37.5
Ans:-B
4. A balanced star-connected load with impedances. of 20 —30 Ohm is supplied from a beta phase, 4-wire, 173 volt system, the voltages to neutral being 100 —90°, 100 30° and 100 150°
The current in the neutral wire is
(a) 5 A
(b) 8.65 A
(c) Zero
(d) 50 A
Ans:-D
5. Two coils in differential connection have self- inductance of 2 mH and 4 mH and a mutual inductance of 0.15 mH. The equivalent inductance of the combination is
(a) 5.7mH
(b) 5.85mH
(c) 6mH
(d) 6.l5mH
Ans:-A
6. Two wattmeters connected to measure the power in a 3-phase balanced delta connected load read W1= 12 kW and W2 = 15 kW respectively. If the same load is reconnected in star, then the wattmetets would read
(a) W1 = 8.66 kW, W2 = 6.93 kW
(b) W1 = 6.93 kW, W2 = 8.66 kW
(c) W1 = 5kW, W2 = 4kW
(d) W1= 4kW, W2 = 5kW
Ans:-C
7. When compared to a first-order low-pass filter, a second-order low-pass filter has
(a) Lower voltage gain
(b) Higher voltage gain
(c) Faster drop in filter response
(d) Higher cut-off frequency
Ans:-D
8. Match List I with List II and select the correct answer using the codes given below the lists:
List I
(Hybrid parameters)
A. h11
B. h22
C. g11
D. g22
List II
(Relation with immittance parameters)
1. 1 / Y11
2. 1 / Z 22
3. 1 / Z 11
4. 1 / Y 22
Codes:
A B C D
(a) 12 3 4
(b) 3 2 1 4
(c) 1 4 3 2
(d) 3 4 1 2
Ans:-B
9. To improve stability and time response of a control system, poles are often added to the system transfer function. In this context which
one of the following pairs is correctly matched?
(a) Zero poles ...make the system stable and slow responding
(b) One pole ... makes the system less stable and slow responding
(c) Two poles ...make the system less stable and fast responding
(d) Three poles ... make the system conditionally stable and fast responding
Ans:-C
10. Consider the following statements regarding root loci:
1. All root loci start from the respective poles of G(s) H(s).
2. All root loci end at the respective zeros of G(s) H(s) or go to infinity.
3. The root loci are symmetrical about the imaginary axis of the s-plane.
Of these statements:
(a) 1, 2 and 3 are correct
(b) 1 and 2 are correct
(c) 2 and 3 are correct
(d) 1 and 3 are correct
Ans:-B
11. Consider the following statements:
Addition of resistance to the rotor of a two-phase ac servomotor will
1. Increase the overall torque.
2. Increase the stability of operation.
3. Linearize its torque-speed characteristics.
4. Lead to attainment of maximum stalling torque
Of these statements:
(a) 1, 2 and 4 are correct
(b) 2, 3 and 4 are correct
(c) 2 and 3 are correct
(d) 1, 3 and 4 are correct
Ans:-C
12. A 6-pole lap-connected dc generator with 480 conductors has an armature resistance of 0.06 ohm. If the conductors are reconnected to form a wave winding, other things remaining unchanged, the value of the armature resistance will be
(a) 0.01 ohm
(b) 0.06 ohm
(c) 0.36 ohm
(d) 0.54 ohm
Ans:-D
13. A 2-pole series motor with its two field coils connected in series runs at a speed of 500 rpm. If the field coils ar reconnected in parallel and assuming that the torque is constant and the magnetic circuit is unsaturated, the new speed will be
(a) 250 rpm
(b) 500/ √2rpm
(c) 500 √rpm
(d) 1000 rpm
Ans:-D
14. Consider the following statements:
As a 3-phase induction motor is loaded from no- load to rated load,
1. there is an improvement in the power factor.
2. the torque increases almost in proportion to slip.
3. the air-gap flux falls sharply.
Of these statements:
(a) 1,2 and 3 are correct 4
(b) 1 and 2 are correct
(c) 2 and 3 are correct
(d) 1 and 3 are correct
Ans:-B
15. Short-circuit ratio of a synchronous machine is the ratio of the
(a) open-circuit voltage to the short-circuit current at a given excitation
(b) short-circuit current to the open-circuit voltage at a given excitation
(c) excitation current required for the rated voltage on open-circuit to the excitation current required for the rated armature current under short-circuit
(d) excitation current required for the rated
armature current under short-circuit to the excitation current required for rated voltage on open-circuit
Ans:-C
16. In a 3-phase induction motor, the angular speed of the stator field is ω and, the actual angular speed of the rotor is w r’, and the stator induced emf is given by es = NI, ω K ws Ø sin ωt, (N1 being the stator turns/phase), the rotor emf with N2 as the rotor/turns phase will be (K ws = stator winding factor and K wr =. rotor winding factor)
(a) e r = N2 ω K W r sin ω t
(b) e r =N2 ω r K wr sin ωr t
(c) e r = N2 (ω - ωr) Kωr Ø sin(ω —r)t
(d) e r = N2 ( ω+ ωr) K ωrØ sin (ω + ω r) t
Ans:-A
17. A 3-phase induction motor requires a starter
(a) because there is no back emf induced in the stator winding during starting
(b) because the motor does not possess an inherent starting torque
(c) because the induced secondary voltage and hence the currents in the windings are abnormally high during starting
(d) to increase the starting torque
Ans:-C
18. For a rotor-fed 3-phase induction motor, the absolute speed of the rotating magnetic field in space is
(a) the synchronous speed
(b) the difference between the synchronous speed and the rotor speed
(c) the rotor speed
(d) zero
Ans:-A
19. A synchronous machine connected to infinite bus bars is initially delivering active power to and absorbing lagging reactive power from the bus bars. As increase in the power input to the synchronous machine will cause
(a) an increase in both armature current and power factor
(b) an increase in armature current and a decrease in power factor
(c) a decrease in both armature current and power factor
(d) a decrease in armature current and an increase in power factor.
Ans:-A
20. The introduction of interpoles in between the main poles improves the performance of a dc machine, because
(a) the interpoles produce additional flux to augment the developed torque
(b) the flux waveform is improved with reduction in harmonics
(c) the inequality of air-gap flux on the top and bottom halves of the armature is removed
(d) a counter-emf is induced in the coil undergoing commutation
Ans:-C
21. For proper synchronisation of a large synchronous machine to a bus, the frequency of the-incoming machine
(a) should be exactly the same as that of the bus
(b) should be slightly higher than that of the bus
(c) should be slightly lower than that of the bus
(d) can be of any value
Ans:-B
22. A 3-phase alternator delivers power to a balanced 3-phase load of power factor 0.707 lagging. It is observed that the open-circuit emf phasor leads the corresponding terminal voltage phasor by 15°. Neglecting the effect of harmonies, the angle between the axis of the main field mmf and the axis of the armature mmf will be
(a) 300 electrical
(b) 60° electrical
(c) 90° electrical
(d) 150° electrical
Ans:-B
23. A 3-phase, 400 V, delta connected alternator has a synchronous impedance of (0+j20) ohms per phase. If it delivers a balanced load of 12 WA at zero power factor leading, then the percentage ‘voltage regulation of the alternator
is equal to
(a) —50
(b) +50
(c) —150
(d) +150
Ans:-C
24. If the height to width ratio of the window of core- type transformer is increased, then
(a) its leakage reactance and percentage voltage regulation will decrease
(b) its leakage reactance and percentage voltage regulation will increase
(c) its leakage reactance will be unaffected but total space in the window will increase to accommodate the windings better
(d) efficiency will increase and temperature rise will decrease
Ans:-A
25. A 220 / 110V, 50 Hz single-phase transformer having a negligible winding resistances operates from a variable voltage, variable frequency supply such that V I/f (V1 = primary applied voltage, f = source frequency) is constant. This will bring in, in the given range of frequencies,
(a) variation in both eddy current loss and hysteresis loss
(b) variation only in the eddy current loss, hysteresis loss remaining constant
(c) variation only in the hysteresis loss, eddy current loss remaining constant
(d) no change either in the eddy current loss or the hysteresis loss
Ans:-A
26. On direct on line (DOL) starting, dc motor is found to rotate in the direction opposite to that for which it was designed. The motor is a
(a) series motor
(b) shunt motor
(c) cumulatively compounded, motor
(d) differential compounded motor
Ans:-D
27. Consider the following statements:
To control the speed of a dc shunt motor above the base speed over a reasonably wide range, the motor must
1. have compensating winding
2. have interpole winding.
3. be started using a 3-point starter.
4. be started using a 4-point starter.
Of these statements:
(a) l, 2and 4arecorrect
(b) 1, 2 and 3 are correct
(c) 1 and 3 are correct
(d) 2 and 4 are correct
Ans:-A
28. Consider the following types of drives:
1. Slip energy recovery schemes with converter cascade in the rotor circuit.
2. Stator voltage control using ac voltage controller.
3. Constant V/f control (V = applied voltage, f = frequency).
4. Variable voltage and variable 7requency schemes with air-gap flux constant.
Those suitable for blowers and centrifugal pumps (T α N2) include
(a) l, 3and 4
(b) l, 2 and3
(c) l, 2 and 4
(d) 2, 3 and4
Ans:-B
29. In the case of a thyristor, di /dt capability can be improved by
(a) thermal triggering
(b) voltage triggering
(c) dV / dt triggering
(d) gate pulse triggering
Ans:-A
30. A 3-phase overhead transmission line has its conductors horizontally spaced with spacing between adjacent conductors equal to ‘d’ If, now, the conductors of the lines are rearranged to form an equilateral triangle of sides equal to ‘d’, then the
(a) average capacitance as well as average inductance will increase
(b) average capacitance will decrease but the average inductance will increase
(c) average capacitance will increase but the average inductance will decrease
(d) surge impedance loading of the lines will increase
Ans:-C
electrical engineering solved question papers
electrical engineering solved question papers
Solved Question Papers for Electrical Available Online
Solved Question Papers Of electrical engineering
Directions: The following items consist of two statements, one labelled the ‘Assertion A’ and the other labelled the ‘Reason R’. You are to examine these two statements carefully and decide if the Assertion A and the Reason R is individually true and if so, whether the Reason is a correct explanation of the Assertion. Select your answer to these items using the codes given below and mark your answer sheet accordingly.
Codes:
(a) Both A and R is true and R is the correct explanation of A
(b) Both A and R is true but R is not a correct explanation of A
(c) A is true but R is false
(d) A is false but R is true
1. Assertion (A): Mho relay is widely preferred for the protection of long transmission lines.
Reason (R): Mho relay is stable under power swing conditions.
Ans:-A
2. If I(s) is found to be
1 / s(s+2)(s+5)
then the final value of I (i.e. I at t = ? will be
(a) 10
(b) 1.0
(c) 0.667
(d) 0.1
Ans:-D
3. In a series RLC circuit, the voltage across the inductance as a function of frequency will be maximum
(a) just before resonant frequency
(b) at resonant frequency
(c) just after resonant frequency
(d) both just before and just after resonant frequency
Ans:-C
4. In a balanced delta connected resistive load when one resistor is open-circuited, then the power drawn by the load
(a) is reduced by 1/3
(b) is increased by 1/3
(c) remains same
(d) is reduced by 1/2
Ans:-A
5. Two perfectly coupled coils each of one Henry self-Inductance are connected In parallel so as to aid each other. The overall Inductance is
(a) 2H
(b) 1H
(c) l/2H
(d) zero
Ans:-C
6. Consider the components of E and H listed below:
1.Ex
2.Ey
3.Ex
4.Hy
5.Hz
For a plane wave travelling in x-direction and linearly polarizes in y-direction
(a) 1, 2 and 5 exist
(b) 1, 3 and 4 exist;
(c) 3 and 4 exist
(d) 2 and 5 exist
Ans:-A
7. For a standard feedback control loop, the sensitivity of the closed-loop transfer function T to forward path gain G and feedback path gain H are
STG STH
(a) 1/(1+GH) —1/(1 +GH)
(b) —GH(1+GH) —H/(1 + GH)
(c) G/(1 +GH) 1/(1 + GH)
(d) 1/(1+GH) -GH/(1 + GH)
Ans:-D
8. Consider the following features:
1. Its pole is located to the left of its zero.
2. It decreases the margin of stability of the system.
3. It speeds up the system transient response. Those associated with a lead compensator would include
(a) l, 2 and 3
(b) 1 and 2
(c) 2 and 3
(d) l and 3
Ans:-D
9. A servomotor is usually designed to have
(a) high rotor inertia and high bearing friction
(b) high rotor inertia and low bearing friction
(c) low rotor inertia and high bearing friction
(d) low rotor inertia and low bearing friction
Ans:-D
10. Match List I with List II and select the correct answer using the codes given below the lists:
List I
(Measuring Bridge)
A. Maxwell bridge
B. Anderson bridge
C. Heaviside Campbell bridge
List II
(Unknown self- inductance is compared with)
1. Known value of self-inductance
2. Known value of capacitor
3. Known value of mutual inductance
Codes:
A B C
(a) 1 2 3
(b) 1 3 2
(c) 3 1 2
(d) 2 1 3
Ans:-A
11. Which of the following compensations are provided in the induction type energy meter for correct measurement of energy?
1. Friction compensation
2 Power factor compensation
3. Frequency compensation
4. Overload Compensation
Select the correct answer from the codes given below:
Codes
(a) 1, 2 and 3
(b) l, 2 and 4
(c) l, 3 and 4
(d) 2, 3 and 4
Ans:-B
12. To measure the angular position ? of a shaft which is free to rotate continuously and if the measurement is to be carried out with high precision, the transducer to be selected would be
(a) potentiometer
(b) synchro
(c) resolver
(d) tachometer
Ans:-B
13.. A piezoelectric transducer has the following parameter values:
Crystal capacitance = 10-9 F
Cable capacitance = 2 x 1010F
Charge sensitivity = 4 x 10-6 coulombs/cm
if the oscilloscope used for read-out has input resistance of 1 M? In parallel with
C = 4 x 10-10F, then the voltage sensitivity constant will be
(a) 2500 volts/cm
(b) 3334 volts/cm
(c) 4000 volts/cm
(d) 4500 volts/cm
Ans:-A
14. In a certain telemetry system, the measured values are converted to digital form. The digital values can then be transmitted via FSK (binary or quaternary) or BPSK or QPSK systems. Out of these, the best noise immunity can be obtained with.
(a) binary FSK
(b) quaternary FSK
(c) BPSK
(d) QPSK
Ans:-B
15. What is the correct increasing order of the following frequencies connected with the junction transistor operation?
1. fT
2. f?
3. f?
Select the correct answer from the codes given below:
Codes:
(a) 1,2,3
(b) 2,3,1
(c) 2,1,3
(d) 3,1,2
Ans:-C
16. The h parameter equivalent circuit is the most common representation of the junction transistor because
(a) it is usable over the entire frequency band of interest to the transistor
(b) the parameters values correspond to input impedance, output admittance and current gain for the most common applications of the transistor
(c) it represents the admittance parameters of the transistors
(d) it is most useful in the ON and OFF states of the transistor
Ans:-A
17. A power amplifier uses transistor of maximum power dissipation rating of 10 watts. Match the operating classes of List I with possible output power ratings of List II and select the correct answer using the codes given below the lists:
List I
(Operation)
A. Single-ended class A
B. Push-pull class A
C. Single-ended class B
D. Push-pull class B
List II
(Ideal Power Output)
1. l0W
B. 20W
C. 30W
4. 37W
Codes:
A B C D
(a) 1 1 4 4
(b) 2 2 3 3
(c) 3 3 4 4
(d) 1 2 3 4
Ans:-C
18. A carrier voltage is simultaneously amplitude modulated by two sine waves causing modulation in dices of 0.4 and 0.3. The overall rms value of modulation index Is
(a) 0.10
(b) 0.35
(c) 0.50
(d) 0.70
Ans:-B
19. An AM transmitter radiates 4 kW with an unmodulated carrier wave and 5 kW when it is amplitude modulated. If the carrier were frequency modulated, then the radiated power will be
(a) 4kW
(b) 5kW
(c) 4.5kW
(d) 8kW
Ans:-A
20. Which one of the following pairs is not correctly matched?
(a) Amplitude demodulation circuit: Diode detector
(b) Frequency demodulation circuit: Ratio detector
(c) Phase demodulation circuit: Coherent detector
(d) Pulse demodulation circuit: TDM
Ans:-C
21. How many steps are there in the output of a 10- bit D/A converter?
(a) 1023
(b) 1024
(c) 10
(d) 100
Ans:-A
22. Match List I with List II and select the correct answer using the codes given below the lists:
List I
(.Types of AID converters)
A. Dual Slope
B. Counter-Ramp
C. Successive Approximation
D. Simultaneous
List II
(Properties of AID converters)
1. Fixed conversion time; depends on the no.
of bits
2. High speed operation
3. Hum rejection
4. Conversion time dependent on signal amplitude
5. Large conversion time
Codes:
A B C D
(a) 3 2 5 4
(b) 2 3 4 1
(c) 3 4 1 2
(d) 4 1 2 5
Ans:-A
23. What Is the 2‘s complement of the word 0011 0101 1001 1100?
(a) 1100 1010 0110 0100
(b) 1100 1010 0110 0011
(c) 1100 1010 0110 0101
(d) 0011 0101 1001 1101
Ans:-A
24. There is a sequential circuit which has “N” number of states. If states S1 and S1 can be distinguished by an input sequence of length n, then
(a) n ? N
(b) n ? N—1
(c) n ? N
(d) n ? N—1
Ans:-D
25. The fastest mode of data transfer from CPU to memory in a microprocessor is
(a) memory mapped I/O
(b) 1/0 mapped I/O
(c) interrupt driven I/O
(d) DMA
Ans:-D
26. In the execution of following instructions
MOV AH, MEM
SHR AH, I
SHR AH, I
MOV MEM, AH
which one of the following would hold true?
(a) MEM gets divided by 4
(b) 25 gets added to MEM
(c) 25 gets subtracted from MEM
(d) MEM gets multiplied by 4
Ans:-C
27. Flat top sampling of base band signals leads to
(a) aliasing
(b) aperture effect
(c) under-sampling
(d) impossible reconstruction
Ans:-B
28. The figure-of-merit of an earth station in satellite communication system is specified in terms of
(a) noise temperature
(b) antenna gain
(c) gain-to-noise temperature ratio
(d) sensitivity of the receiver
Ans:-C
29. Consider the following statements: Odd line 2: I. interlacing in television helps in
1. reducing flicker
2. simplifying vertical motion circuitry
3. horizontal synchronisation
4. separation of synchronizing pulse
Of these statements:
(a) 1 and 2 are correct
(b) 2 and 3 are correct
(c) 1 and 4 are correct
(d) 2 and 4 are correct
Ans:-C
30. Serrations are used in the composite video waveform of a television system to
(a) facilitate interlacing
(b) aid generation of vertical sync pulse
(c) aid vertical synchronisation
(d) aid horizontal synchronisation
Ans:-A
Solved Question Papers for Electrical Available Online
Solved Question Papers Of electrical engineering
Directions: The following items consist of two statements, one labelled the ‘Assertion A’ and the other labelled the ‘Reason R’. You are to examine these two statements carefully and decide if the Assertion A and the Reason R is individually true and if so, whether the Reason is a correct explanation of the Assertion. Select your answer to these items using the codes given below and mark your answer sheet accordingly.
Codes:
(a) Both A and R is true and R is the correct explanation of A
(b) Both A and R is true but R is not a correct explanation of A
(c) A is true but R is false
(d) A is false but R is true
1. Assertion (A): Mho relay is widely preferred for the protection of long transmission lines.
Reason (R): Mho relay is stable under power swing conditions.
Ans:-A
2. If I(s) is found to be
1 / s(s+2)(s+5)
then the final value of I (i.e. I at t = ? will be
(a) 10
(b) 1.0
(c) 0.667
(d) 0.1
Ans:-D
3. In a series RLC circuit, the voltage across the inductance as a function of frequency will be maximum
(a) just before resonant frequency
(b) at resonant frequency
(c) just after resonant frequency
(d) both just before and just after resonant frequency
Ans:-C
4. In a balanced delta connected resistive load when one resistor is open-circuited, then the power drawn by the load
(a) is reduced by 1/3
(b) is increased by 1/3
(c) remains same
(d) is reduced by 1/2
Ans:-A
5. Two perfectly coupled coils each of one Henry self-Inductance are connected In parallel so as to aid each other. The overall Inductance is
(a) 2H
(b) 1H
(c) l/2H
(d) zero
Ans:-C
6. Consider the components of E and H listed below:
1.Ex
2.Ey
3.Ex
4.Hy
5.Hz
For a plane wave travelling in x-direction and linearly polarizes in y-direction
(a) 1, 2 and 5 exist
(b) 1, 3 and 4 exist;
(c) 3 and 4 exist
(d) 2 and 5 exist
Ans:-A
7. For a standard feedback control loop, the sensitivity of the closed-loop transfer function T to forward path gain G and feedback path gain H are
STG STH
(a) 1/(1+GH) —1/(1 +GH)
(b) —GH(1+GH) —H/(1 + GH)
(c) G/(1 +GH) 1/(1 + GH)
(d) 1/(1+GH) -GH/(1 + GH)
Ans:-D
8. Consider the following features:
1. Its pole is located to the left of its zero.
2. It decreases the margin of stability of the system.
3. It speeds up the system transient response. Those associated with a lead compensator would include
(a) l, 2 and 3
(b) 1 and 2
(c) 2 and 3
(d) l and 3
Ans:-D
9. A servomotor is usually designed to have
(a) high rotor inertia and high bearing friction
(b) high rotor inertia and low bearing friction
(c) low rotor inertia and high bearing friction
(d) low rotor inertia and low bearing friction
Ans:-D
10. Match List I with List II and select the correct answer using the codes given below the lists:
List I
(Measuring Bridge)
A. Maxwell bridge
B. Anderson bridge
C. Heaviside Campbell bridge
List II
(Unknown self- inductance is compared with)
1. Known value of self-inductance
2. Known value of capacitor
3. Known value of mutual inductance
Codes:
A B C
(a) 1 2 3
(b) 1 3 2
(c) 3 1 2
(d) 2 1 3
Ans:-A
11. Which of the following compensations are provided in the induction type energy meter for correct measurement of energy?
1. Friction compensation
2 Power factor compensation
3. Frequency compensation
4. Overload Compensation
Select the correct answer from the codes given below:
Codes
(a) 1, 2 and 3
(b) l, 2 and 4
(c) l, 3 and 4
(d) 2, 3 and 4
Ans:-B
12. To measure the angular position ? of a shaft which is free to rotate continuously and if the measurement is to be carried out with high precision, the transducer to be selected would be
(a) potentiometer
(b) synchro
(c) resolver
(d) tachometer
Ans:-B
13.. A piezoelectric transducer has the following parameter values:
Crystal capacitance = 10-9 F
Cable capacitance = 2 x 1010F
Charge sensitivity = 4 x 10-6 coulombs/cm
if the oscilloscope used for read-out has input resistance of 1 M? In parallel with
C = 4 x 10-10F, then the voltage sensitivity constant will be
(a) 2500 volts/cm
(b) 3334 volts/cm
(c) 4000 volts/cm
(d) 4500 volts/cm
Ans:-A
14. In a certain telemetry system, the measured values are converted to digital form. The digital values can then be transmitted via FSK (binary or quaternary) or BPSK or QPSK systems. Out of these, the best noise immunity can be obtained with.
(a) binary FSK
(b) quaternary FSK
(c) BPSK
(d) QPSK
Ans:-B
15. What is the correct increasing order of the following frequencies connected with the junction transistor operation?
1. fT
2. f?
3. f?
Select the correct answer from the codes given below:
Codes:
(a) 1,2,3
(b) 2,3,1
(c) 2,1,3
(d) 3,1,2
Ans:-C
16. The h parameter equivalent circuit is the most common representation of the junction transistor because
(a) it is usable over the entire frequency band of interest to the transistor
(b) the parameters values correspond to input impedance, output admittance and current gain for the most common applications of the transistor
(c) it represents the admittance parameters of the transistors
(d) it is most useful in the ON and OFF states of the transistor
Ans:-A
17. A power amplifier uses transistor of maximum power dissipation rating of 10 watts. Match the operating classes of List I with possible output power ratings of List II and select the correct answer using the codes given below the lists:
List I
(Operation)
A. Single-ended class A
B. Push-pull class A
C. Single-ended class B
D. Push-pull class B
List II
(Ideal Power Output)
1. l0W
B. 20W
C. 30W
4. 37W
Codes:
A B C D
(a) 1 1 4 4
(b) 2 2 3 3
(c) 3 3 4 4
(d) 1 2 3 4
Ans:-C
18. A carrier voltage is simultaneously amplitude modulated by two sine waves causing modulation in dices of 0.4 and 0.3. The overall rms value of modulation index Is
(a) 0.10
(b) 0.35
(c) 0.50
(d) 0.70
Ans:-B
19. An AM transmitter radiates 4 kW with an unmodulated carrier wave and 5 kW when it is amplitude modulated. If the carrier were frequency modulated, then the radiated power will be
(a) 4kW
(b) 5kW
(c) 4.5kW
(d) 8kW
Ans:-A
20. Which one of the following pairs is not correctly matched?
(a) Amplitude demodulation circuit: Diode detector
(b) Frequency demodulation circuit: Ratio detector
(c) Phase demodulation circuit: Coherent detector
(d) Pulse demodulation circuit: TDM
Ans:-C
21. How many steps are there in the output of a 10- bit D/A converter?
(a) 1023
(b) 1024
(c) 10
(d) 100
Ans:-A
22. Match List I with List II and select the correct answer using the codes given below the lists:
List I
(.Types of AID converters)
A. Dual Slope
B. Counter-Ramp
C. Successive Approximation
D. Simultaneous
List II
(Properties of AID converters)
1. Fixed conversion time; depends on the no.
of bits
2. High speed operation
3. Hum rejection
4. Conversion time dependent on signal amplitude
5. Large conversion time
Codes:
A B C D
(a) 3 2 5 4
(b) 2 3 4 1
(c) 3 4 1 2
(d) 4 1 2 5
Ans:-A
23. What Is the 2‘s complement of the word 0011 0101 1001 1100?
(a) 1100 1010 0110 0100
(b) 1100 1010 0110 0011
(c) 1100 1010 0110 0101
(d) 0011 0101 1001 1101
Ans:-A
24. There is a sequential circuit which has “N” number of states. If states S1 and S1 can be distinguished by an input sequence of length n, then
(a) n ? N
(b) n ? N—1
(c) n ? N
(d) n ? N—1
Ans:-D
25. The fastest mode of data transfer from CPU to memory in a microprocessor is
(a) memory mapped I/O
(b) 1/0 mapped I/O
(c) interrupt driven I/O
(d) DMA
Ans:-D
26. In the execution of following instructions
MOV AH, MEM
SHR AH, I
SHR AH, I
MOV MEM, AH
which one of the following would hold true?
(a) MEM gets divided by 4
(b) 25 gets added to MEM
(c) 25 gets subtracted from MEM
(d) MEM gets multiplied by 4
Ans:-C
27. Flat top sampling of base band signals leads to
(a) aliasing
(b) aperture effect
(c) under-sampling
(d) impossible reconstruction
Ans:-B
28. The figure-of-merit of an earth station in satellite communication system is specified in terms of
(a) noise temperature
(b) antenna gain
(c) gain-to-noise temperature ratio
(d) sensitivity of the receiver
Ans:-C
29. Consider the following statements: Odd line 2: I. interlacing in television helps in
1. reducing flicker
2. simplifying vertical motion circuitry
3. horizontal synchronisation
4. separation of synchronizing pulse
Of these statements:
(a) 1 and 2 are correct
(b) 2 and 3 are correct
(c) 1 and 4 are correct
(d) 2 and 4 are correct
Ans:-C
30. Serrations are used in the composite video waveform of a television system to
(a) facilitate interlacing
(b) aid generation of vertical sync pulse
(c) aid vertical synchronisation
(d) aid horizontal synchronisation
Ans:-A
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