Previous year papers of HPCL (Electrical and Electronics)

Will you please provide me the Previous year papers of HPCL (Electrical and Electronics)???

Yes sure, here I am providing you the Previous year papers of HPCL (Electrical and Electronics), there are objective types of the questions available,

HPCL Previous years electronics and Electrical questions with answers

1. Mho relay is usually employed for the protection of
a) Short lines only
b) Medium lines only
c) Long lines only
d) Any line
Ans: Long lines only

2. A modern power semiconductor device IGBT is combines the characteristics of
a) BJT and MOSFET
b) FCT and GTO
c) SCR and MOSFET
d) SCR and BJT
Ans: BJT and MOSFET

3. For a single-phase a.c. to d.c. controlled rectifier to operate in regenerative mode, which of the following conditions should be satisfied?
a) Half –controlled bridge, a 90°, source of e.m.f. in load
c) Full-controlled bridge, a > 90°, source of e.m.f. in load
d) Full-controlled bridge, a 90°, source of e.m.f. in load4. Which is the most suitable power device for high frequency ( more 100 kHz) switching application?
a) Power MOSFET
b) BJT
c) SCR
d) UJT
Ans: Power MOSFET

5. In a thyristor Latching current is ________ than Holding current
a) Equal
b) Less
c) Greater
d) None
Ans: Greater

6. The transfer function of a system is 10/(1+s) when operating as a unity feedback system, the steady state error to a step input will be
a) 0
b) 1/11
c) 10
d) Infinity
Ans: 1/11

7. Which one of the following statements for a dc machine which is provided with inter pole winding (IW) as well as compensating winding (CW) is correct
a) Both IW and CW are connected in series with Armature winding
b) Both IW and CW are connected in parallel with Armature winding
c) IW connected in series but CW is connected in parallel with Armature winding
d) CW connected in series but IW is connected in parallel with Armature winding
Ans: Both IW and CW are connected in series with Armature winding

8. A 0-10 mA PMMC ammeter reads 5mA in a circuit; its bottom control spring snaps out suddenly the meter will now read.
a) 5mA
b) 10mA
c) 2.5mA
d) 0
Ans: 0

9. A dc cumulatively compounded motor delivers rated load torque at rated speed. If series field is short circuited, then the armature current and speed will
a) Both increases
b) Both decreases
c) Increases and decreases
d) Decreases and increases
Ans: Both increases

10. Moving coil in dynamometer wattmeter connected
a) In series with fixed coil
b) Across supply
c) In series with load
d) Across load
Ans: Across supply

11. In an induction machine, if the air gap increased
a) Speed will be reduced
b) Efficiency will be improved
c) Power factor will be lowered
d) Breakdown torque will be reduced
Ans: Power factor will be lowered

12. A CRO screen has ten divisions on the horizontal scale. If a voltage signal 5 sin 314t+45 deg)is examined with a line base settings of 5 msec/div, the number of cycles of signal displayed on the screen will be
a) 0.5 cycles
b) 2.5 cycles
c) 5 cycles
d) 10 cycles
Ans: 2.5 cycles

13. A 3-phase 50HZ SCIM takes a power input of 30 KW at its full load speed of 1440 rpm. Total stator losses are 1 KW. The slip and rotor ohmic losses at full load are
a) 0.02, 600 W
b) 0.04, 580 W
c) 0.04, 1160 W
d) 0.04, 1200 W
Ans: 0.04, 1160 W

14. Thermocouple is used to measure
a) AC
b) DC
c) Both
d) None
Ans: Both

15. The two watt meters measurement the ratio of two meter readings is –(1-sqrt3) 1+sqrt3) then the power factor is
a) 1
b) 0.866
c) 0.707
d) 0
Ans: 0.707

16. Hays bridge is used to measure___________ and Schering bridge is used to measure____________
a) Inductance, Inductance
b) Inductance, Capacitance
c) Capacitance, Inductance
d) Resistance, Capacitance
Ans: Inductance, Capacitance

17. When sine wave is given as input to Schmitt trigger then its generates
a) Sine wave
b) Saw tooth wave
c) Triangle wave
d) Square wave
Ans: Square wave

18. In Gauss Seidel method the following factors are influenced for operation
a) Acceleration factor
b) Selection of slack buss
c) Both
d) None
Ans: Selection of slack buss*

19.
i. (X’+Y’) A. Low-pass filter function
ii. (X’Y’) B. Sum
iii. (XY) C. NAND
D. Carry
E.NOR
a) i-C, ii-E, iii-D
b) i-C, ii-E, iii-B
c) i-C, ii-B, iii-D
d) i-C, ii-E, iii-A
Ans: i-C, ii-E, iii-D

20. The phase lead compensation is used to
a) Increase rise time and decrease overshoot
b) Decrease both rise time and overshoot
c) Increase both rise time and overshoot
d) Decrease rise time and increase overshoot
Ans: Decrease rise time and increase overshoot

21. Voltage feed back amplifier is a
a) Shunt-Shunt
b) Shunt-Series
c) Series-Shunt
d) Series- Series
Ans: Shunt-Shunt

22. In microprocessor the next instruction to be executed is stored in
a) Program Counter
b) Stack Pointer
c) Memory Pointer
d) Accumulator
Ans: Program Counter

23. The following element retains it energy after source is disconnected
a) Resister
b) Inductor
c) Capacitor
d) Thermistor
Ans:

24. In series RLC circuit at resonant
a) Voltage is in phase with current
b) Current is maximum
c) Inductive reactance = Capacitive reactance
d) All of the above
Ans: All of the above

25.For RC low pass filter R=100 K ohms, C= 5 micro farads then lower cutt of frequency is
a) 1 K HZ
b) 0 HZ
c) 381.3 HZ
d) Infinity
Ans:

26. V=100Sin (1000t+46 deg), I=2Sin (1000t+80 deg) what are the elements in the circuit
a) R=30 ohm, L=30 mH
b) R=30 ohm, C=33.3 micro farads
c) R=40 ohm, L=30 mH
d) R=40 ohm, L=33.3 micro farads
Ans: R=40 ohm, L=33.3 micro farads
27. L=10 mH, I=100Sin50t 0

28. In dielectric measurement, the dielectric loss is proportional to
a) F
b) V
c) I
d) Vsqr
Ans: Vsqr

29. G(s) = (1-s)/s(s+2) then closed loop transfer function is
a) Unstable
b) Stable
c) Marginally stable
d) All
Ans: Stable

30. G(s) = (1+0.5s)/(1+s) find which type of net work it is
a) Lead net work
b) Lag net work
c) Lag – Lead net work
d) Lead – Lag net work
Ans: Lag net work

31. Temperature of electrode in Arc furnace is
a) 1000 deg
b) 1500 deg
c) 1500 deg to 3500 deg
d) 4500 deg

32. In bode plot the point which separates the lower and upper frequencies is called
a) Critical point
b) Cut-off point

33. Nyquest stability is used to determine
a) Absolute Stability
b) Relative Stability
c) Both
d) None
Ans: Both*

34. When 220V dc shunt alternator generating the voltage at rated value. If direction of rotation is reversed, then alternator will
a) Build up its voltage with same polarity
b) Build up its voltage with opposite polarity
c) No build up of voltage
d) None
Ans: No build up of voltage

35. Over lap Angle depends on_________
a) Load inductance
b) Loa capacitance
c) Source inductance
d) Source capacitance
Ans: Source inductance

36. Area under speed time curve gives
a) Time
b) Speed
c) Distance
d) None
Ans: Distance

37. The regulation of Short Transmission lines depends up on
a) Distance of line
b) Frequency
c) Power factor
d) All
Ans: Power factor

38. Which of the following plant is having lowest load factor?
a) Diesel Plant
b) Pumped storage Plant
c) Thermal Plant
d) Nuclear Plant
Ans: Diesel Plan

39. For SR latch whent the out put is undesirable
a) 0, 0
b) 1, 0
c) 0, 1
d) 1, 1
Ans: 1, 1

40. For interrupting capacitive currents which Circuit Breaker (CB) is used
a) SF6 CB
b) Oil CB
c) Vacuum CB
d) Air blast CB
Ans: Vacuum CB

41. For V/F control, when frequency is increased in transformer
a) Core loss component current increases, Magnetizing component current decreases
b) Core loss component current increases, Magnetizing component current increases
c) Core loss component current decreases, Magnetizing component current decreases
d) Core loss component current decreases, Magnetizing component current increases
Ans: Core loss component current decreases, Magnetizing component current decreases
42. In ceiling fan the angle between auxiliary winding a main winding is
a) 0 deg
b) 90 deg
c) 180 deg
d) 360 deg
Ans: 90 deg

43. In a shaded pole motor, shaded rings are used to
a) Field flux production
Ans: Field flux production

44. Practical method of improving string efficiency
a) Increasing crass arms length
b) Using different size of insulators
c) Using different insulator materials
d) Using of guard rings
Ans: Increasing crass arms length*

45. In which type of fault all 3-phase components are equal
a) L-G
b) L-L
c) L-L-G
d) 3-Phase fault
Ans: 3-Phase fault

46. 11/220 KV 100 MVA transformers, the primary base voltage rating is 10 KV then secondary base KV is
a) 10 KV
b) 220 KV
c) 220/sqrt3
Ans: 220/sqrt3*

47. Water hamming effect is occurs in
a) Surge tank
b) Penstock
c) Turbine
d) Reservoir
Ans: Penstock

48. Transient stability can be improved by
a) By putting series capacitor
b) By using dynamic resister
c) Auto re-closers
d) All of the above
Ans: All of the above

49. If sending end voltage is Vs at no-load in a transmission line then receiving end voltage is if ABCD parameters of line is given
a) Vs
b) Vs/A
c) 0
d) Infinity
Ans: Vs/A

50. Harmonics are eliminated by using
a) Skewing of rotor
b) Distribution winding
c) Short pitch winding
d) All of the above
Ans: All of the above

__________________
Answered By StudyChaCha Member

Hello friend here I am providing you Previous year question papers of HPCL (Electrical and Electronics).

ELECTRONICS

Q. Power diode is generally made from
a) Silicon
b) Germanium
c) Both
d) None of these

Q. When the both junction of NPN diode is reverse biased, then the diode is in which mode
a) Active
b) Cutoff
c) Saturation
d) inverted

Q. Which transistor mode gives the inverted output
a) Common Emitter
b) Common Base
c) Common Collector
d) None of these

Q. Which coupling gives the higher gain in case of amplifier
a) Capacitor coupling
b) Impedance coupling
c) Transformercoupling

Q. Which distortion is least objectionable in audio amplification
a) Phase
b) Frequency
c) Harmonic
d) Intermediation

Q. A narrow band amplifier has a band pass nearly…………of central frequency
a) 33.3%
b) 10%
c) 50%

Q. Phase shift oscillator consists
a) RL
b) RC
c) RLC

Q. Multivibrater Produces
a) Sine wave
b) Square wave
c) Smooth wave
d) sawtooth

Q. Convert the 101101 Binary number into octal no
a) 65
b) 55
c) 51
d) 45

Ans: 55

Q. 10 in BCD
a) 10100
b) 1100
c) 010111
d) None of these

Ans: None of these

Q. Which PNP device has a terminal for synchronizing purpose
a) SCS
b) Triac
c) Diac
d) SUS

Q. Addition of indium in semiconductor crystal makes
a) PNP
b) NPN

Q. Free electron exists in which band
a) 1
b) 2
c) 3
d) Conduction band

Q. Ripple factor of half wave rectifier
a) 1.21
b) 0.48
c) 0.5

Q. Transistor that can be used in enhancement mode
a) NPN
b) UJT
c) JFET
d) MOSFET

Q. Following contributes to harmonic distortion in Amplifier
a) +Ve feedback
b) –Ve feedback
c) Defective active device

Q. High cutoff frequency
a) CB
b) CC
c) CE

Q. Which is used as data selector?
a) Encoder
b) Decoder
c) modulator
d) Demodulator

Q. Read write capable memory
a) RAM
b) ROM
c) Both
d) None of these

Q.the radix or base of hexadecimal number system is ———–
a) 8
b) 16
c) 5
d) none of these

Ans: 16

Q.the no of 1’s in the binary representation of the expression 162*9+162*7+16*5+3 are
a) 10
b) 23
c) 6
d) 4

Q. the no of latches in F/F are ——-
a) 1
b) 2
c) 3
d) 4

Q.how many flip-flops are required to construct Mod -12 counter
a) 5
b) 4
c) 12
d) none

Ans: 4

Q. which logic gate has the output is compliment of its input ———-
a) OR
b) AND
c) NOT
d) X-OR

Ans: NOT

Q.no.of 2-input multiplexers needed to construct a 210 input multiplexer…….
a) 12
b) 31
c) 20
d) 16

Q.By adding inverters to the inputs and output of a AND gate we can obtain ……………
a) OR
b) AND
c) NOT
d) X-OR

Ans: X-OR

Q.how many NAND gates are needed to realize OR gate ————–
a) 1
b) 2
c) 3
d) 4

Ans: 3

Q.which is the first integrated logic family —————
a) RTL
b) DTL
c) TTL
d) none of these

Q. Which logic gate has output high if and only if all inputs are low ———?
a) NOR
b) NAND
c) X-NOR
d) AND

Ans: NAND

Q.According to Boolean algebra 1+A+B+C =
a) A
b) A+B+C
c) 1
d) none of these

Ans: 1

Q. If a=0x6db7 and b=0x2ae9 then what is the value of a”b————–
a) binary number for 1001.1101?
b) decimal number for 19?
c) excess-3 code for 29?

Q.what is the value of A’+1 ?
a) A
b) A’
c) 1
d) none of these

Ans: 1

Q.2 in 4 bit number one bit indicates sign of the number then the locations are from
a) -8 to 8
b) -7 to 7
c) -16 to 16
d) None

Q.Avalanche photo diode is used when compared to PIN diode bcz
a)larger band width
b)high sensitivity
C)——-
d)——–

Q.some non zero DC voltage is to RC low pass circuit then the DC voltage in the output contains
a) Same as in input
b) Higher than input
c) Zero
d) Slightly increases

Q.if the output of the gate is always high then the gates applied to this logic are 0,0
a) NAND and EX-NOR
b) NAND and NOR
c) AND and X-NOR
d) OR and XOR

Ans:a

Q.Thermal Run away is not possible in FET bcz the flow of
a)minority careers
b)Transconductance
c)_____
d)none

Ans : minority careers

Q.which of the following is/are true about 1’s and 2’s compements:
i)In 1’s complement form. 0 has two representations
ii)in 1’s complement, the magnitude of lowest number is equal to the magnitude of highest number
iii)In 2’s complement, 0 has two representations

a) i only
b) i and ii
c) iii only
d) all of these

Q.In the hybrid parameter model of a transistor reverse transfer voltage ratio and forward transfer current ratio are respectively given by:
a) h11 and h21
b) h12 and h11
c) h21 and h11
d) None of these

Q.The largest negative no can be represented with 8 bits in 2’s compliment representation?
a)-256
b)-255
c)-127
d)-128

Ans: -128

Q. How many NAND gates required to implement AB+CD+EF
a) 1
b) 2
c) 3
d) 4

Ans: 4

Q. Transparent latch is seen in which type of flip flop
a) SR FF
b) D FF
c) JK FF
d) D FF

Ans: D FF

Q. Odd parity generator uses which logic?
a) Digital
b) Analog
c) Sequential
d) none

Q. Which type of ADC is fastest?
a) SARC
b) Counter type
c) Intigrated type
d) Flash

ANS: Flash/Parallel

Q. Which one of the following is fastest read/writable memory?
a) PROM
b) EEPROM
c) Flash
d) none

Ans: Flash

8. In array programming which one is used
a) SISD
b) PISD
c) MISD
d) None

Q.Which one of the following has high I/p impedance
a) CC
b) CB
c) CE
d) None

Q. The maximum time allowed time for each flip flop for a mod 10 synchronous counter if each flip flop delay is 25ns.
a) 25 ns
b) 50 ns
c) 100 ns
d) none

Q. The resolution for a DAC is given by 0.4% then no. of bits of DAC is
a) 8- bits
b) 16- bits
c) 32- bits
d) none

Ans: 8- bits

41) The chip capacity is 256 bits, then the no.of chips required to build 1024 B memory Is
a) 32
b) 16
c) 15
d) 4

Q. Which of the following are correct?
1)A flip-flop is used to store 1-bit of information
2)Race around condition occurs in JK flip flop when both the inputs are 1
3)Master slave flip flop is used to store 2 bits of information
4)A transparent latch consists of a D- flip flop

a) 1,2,3
b) 1,3,4
c) 1,2,4
d) 2,3,4

Ans: 1,2,4

Q. output resistance of ideal OP AMP is
a) 0
b) 1
c) infinite
d) very high

ANS: 0

Q. CMRR of an OP AMP is given as 80db and Ad is 20000.Value of Acm will be
a) 4
b) 8
c) 2
d) 1

Ans: 2

Q.Si,Ge lie in ……..block of periodic table
a) III
b) V
c) IV A
d) IV B

Ans: IV A

Q.to obtain 10 mV resolution on 5 V range how many bit DAC is to be used
a) 4
b) 8
c) 16
d) 32

Q.% resolution of a 10 bit ADC
a) 1.588%
b) 0.392%
c) 0.0978%
d) 0.0244%

Ans: 0.0978%

Q.Efficiency of half wave rectifier
a) 45%
b) 50%
c) 86%
d) 100%

Electrical:

1. Who relay is usually employed for the protection of
a) Short lines only
b) Medium lines only
c) Long lines only
d) Any line
Ans: Long lines only

2. A modern power semiconductor device IGBT is combines the characteristics of
a) BJT and MOSFET
b) FCT and GTO
c) SCR and MOSFET
d) SCR and BJT
Ans: BJT and MOSFET

3. For a single-phase a.c. to d.c. controlled rectifier to operate in regenerative mode, which of the following conditions should be satisfied?
a) Half –controlled bridge, a 90°, source of e.m.f. in load
c) Full-controlled bridge, a > 90°, source of e.m.f. in load
d) Full-controlled bridge, a 90°, source of e.m.f. in load

4. Which is the most suitable power device for high frequency ( more 100 kHz) switching application?
a) Power MOSFET
b) BJT
c) SCR
d) UJT
Ans: Power MOSFET

5. In a thyristor Latching current is ________ than Holding current
a) Equal
b) Less
c) Greater
d) None
Ans: Greater

6. The transfer function of a system is 10/(1+s) when operating as a unity feedback system, the steady state error to a step input will be
a) 0
b) 1/11
c) 10
d) Infinity
Ans: 1/11

7. Which one of the following statements for a dc machine which is provided with inter pole winding (IW) as well as compensating winding (CW) is correct
a) Both IW and CW are connected in series with Armature winding
b) Both IW and CW are connected in parallel with Armature winding
c) IW connected in series but CW is connected in parallel with Armature winding
d) CW connected in series but IW is connected in parallel with Armature winding
Ans: Both IW and CW are connected in series with Armature winding

8. A 0-10 mA PMMC ammeter reads 5mA in a circuit; its bottom control spring snaps out suddenly the meter will now read.
a) 5mA
b) 10mA
c) 2.5mA
d) 0
Ans: 0

9. A dc cumulatively compounded motor delivers rated load torque at rated speed. If series field is short circuited, then the armature current and speed will
a) Both increases
b) Both decreases
c) Increases and decreases
d) Decreases and increases
Ans: Both increases

10. Moving coil in dynamometer wattmeter connected
a) In series with fixed coil
b) Across supply
c) In series with load
d) Across load
Ans: Across supply

11. In an induction machine, if the air gap increased
a) Speed will be reduced
b) Efficiency will be improved
c) Power factor will be lowered
d) Breakdown torque will be reduced
Ans: Power factor will be lowered

12. A CRO screen has ten divisions on the horizontal scale. If a voltage signal 5 sin 314t+45 deg)is examined with a line base settings of 5 msec/div, the number of cycles of signal displayed on the screen will be
a) 0.5 cycles
b) 2.5 cycles
c) 5 cycles
d) 10 cycles
Ans: 2.5 cycles

13. A 3-phase 50HZ SCIM takes a power input of 30 KW at its full load speed of 1440 rpm. Total stator losses are 1 KW. The slip and rotor ohmic losses at full load are
a) 0.02, 600 W
b) 0.04, 580 W
c) 0.04, 1160 W
d) 0.04, 1200 W
Ans: 0.04, 1160 W

14. Thermocouple is used to measure
a) AC
b) DC
c) Both
d) None
Ans: Both

15. The two watt meters measurement the ratio of two meter readings is –(1-sqrt3) 1+sqrt3) then the power factor is
a) 1
b) 0.866
c) 0.707
d) 0
Ans: 0.707

16. Hays bridge is used to measure___________ and Schering bridge is used to measure____________
a) Inductance, Inductance
b) Inductance, Capacitance
c) Capacitance, Inductance
d) Resistance, Capacitance
Ans: Inductance, Capacitance

17. When sine wave is given as input to Schmitt trigger then its generates
a) Sine wave
b) Saw tooth wave
c) Triangle wave
d) Square wave
Ans: Square wave

18. In Gauss Seidel method the following factors are influenced for operation
a) Acceleration factor
b) Selection of slack buss
c) Both
d) None
Ans: Selection of slack buss*

19.
i. (X’+Y’) A. Low-pass filter function
ii. (X’Y’) B. Sum
iii. (XY) C. NAND
D. Carry
E.NOR
a) i-C, ii-E, iii-D
b) i-C, ii-E, iii-B
c) i-C, ii-B, iii-D
d) i-C, ii-E, iii-A
Ans: i-C, ii-E, iii-D

20. The phase lead compensation is used to
a) Increase rise time and decrease overshoot
b) Decrease both rise time and overshoot
c) Increase both rise time and overshoot
d) Decrease rise time and increase overshoot
Ans: Decrease rise time and increase overshoot

21. Voltage feed back amplifier is a
a) Shunt-Shunt
b) Shunt-Series
c) Series-Shunt
d) Series- Series
Ans: Shunt-Shunt

22. In microprocessor the next instruction to be executed is stored in
a) Program Counter
b) Stack Pointer
c) Memory Pointer
d) Accumulator
Ans: Program Counter

23. The following element retains it energy after source is disconnected
a) Resister
b) Inductor
c) Capacitor
d) Thermistor
Ans:

24. In series RLC circuit at resonant
a) Voltage is in phase with current
b) Current is maximum
c) Inductive reactance = Capacitive reactance
d) All of the above
Ans: All of the above

25.For RC low pass filter R=100 K ohms, C= 5 micro farads then lower cutt of frequency is
a) 1 K HZ
b) 0 HZ
c) 381.3 HZ
d) Infinity
Ans:

26. V=100Sin (1000t+46 deg), I=2Sin (1000t+80 deg) what are the elements in the circuit
a) R=30 ohm, L=30 mH
b) R=30 ohm, C=33.3 micro farads
c) R=40 ohm, L=30 mH
d) R=40 ohm, L=33.3 micro farads

Ans: R=40 ohm, L=33.3 micro farads
27. L=10 mH, I=100Sin50t 0
a)
b)
c)
d)
Ans:

28. In dielectric measurement, the dielectric loss is proportional to
a) F
b) V
c) I
d) Vsqr
Ans: Vsqr

29. G(s) = (1-s)/s(s+2) then closed loop transfer function is
a) Unstable
b) Stable
c) Marginally stable
d) All
Ans: Stable

30. G(s) = (1+0.5s)/(1+s) find which type of net work it is
a) Lead net work
b) Lag net work
c) Lag – Lead net work
d) Lead – Lag net work
Ans: Lag net work

31. Temperature of electrode in Arc furnace is
a) 1000 deg
b) 1500 deg
c) 1500 deg to 3500 deg
d) 4500 deg
Ans:

32. In bode plot the point which separates the lower and upper frequencies is called
a) Critical point
b) Cut-off point
c)
d)
Ans:

33. Nyquest stability is used to determine
a) Absolute Stability
b) Relative Stability
c) Both
d) None
Ans: Both*

34. When 220V dc shunt alternator generating the voltage at rated value. If direction of rotation is reversed, then alternator will
a) Build up its voltage with same polarity
b) Build up its voltage with opposite polarity
c) No build up of voltage
d) None
Ans: No build up of voltage

35. Over lap Angle depends on_________
a) Load inductance
b) Loa capacitance
c) Source inductance
d) Source capacitance
Ans: Source inductance

36. Area under speed time curve gives
a) Time
b) Speed
c) Distance
d) None
Ans: Distance

37. The regulation of Short Transmission lines depends up on
a) Distance of line
b) Frequency
c) Power factor
d) All
Ans: Power factor

38. Which of the following plant is having lowest load factor?
a) Diesel Plant
b) Pumped storage Plant
c) Thermal Plant
d) Nuclear Plant
Ans: Diesel Plan

39. For SR latch whent the out put is undesirable
a) 0, 0
b) 1, 0
c) 0, 1
d) 1, 1
Ans: 1, 1

40. For interrupting capacitive currents which Circuit Breaker (CB) is used
a) SF6 CB
b) Oil CB
c) Vacuum CB
d) Air blast CB
Ans: Vacuum CB

41. For V/F control, when frequency is increased in transformer
a) Core loss component current increases, Magnetizing component current decreases
b) Core loss component current increases, Magnetizing component current increases
c) Core loss component current decreases, Magnetizing component current decreases
d) Core loss component current decreases, Magnetizing component current increases
Ans: Core loss component current decreases, Magnetizing component current decreases

42. In ceiling fan the angle between auxiliary winding a main winding is
a) 0 deg
b) 90 deg
c) 180 deg
d) 360 deg
Ans: 90 deg

43. In a shaded pole motor, shaded rings are used to
a) Field flux production
b)
c)
d)
Ans: Field flux production

44. Practical method of improving string efficiency
a) Increasing crass arms length
b) Using different size of insulators
c) Using different insulator materials
d) Using of guard rings
Ans: Increasing crass arms length*

45. In which type of fault all 3-phase components are equal
a) L-G
b) L-L
c) L-L-G
d) 3-Phase fault
Ans: 3-Phase fault

46. 11/220 KV 100 MVA transformers, the primary base voltage rating is 10 KV then secondary base KV is
a) 10 KV
b) 220 KV
c) 220/sqrt3
d)
Ans: 220/sqrt3*

47. Water hamming effect is occurs in
a) Surge tank
b) Penstock
c) Turbine
d) Reservoir
Ans: Penstock

48. Transient stability can be improved by
a) By putting series capacitor
b) By using dynamic resister
c) Auto re-closers
d) All of the above
Ans: All of the above

49. If sending end voltage is Vs at no-load in a transmission line then receiving end voltage is if ABCD parameters of line is given
a) Vs
b) Vs/A
c) 0
d) Infinity
Ans: Vs/A

50. Harmonics are eliminated by using
a) Skewing of rotor
b) Distribution winding
c) Short pitch winding
d) All of the above
Ans: All of the above

__________________
Answered By StudyChaCha Member