As you want to get the Hindustan Aeronautics Limited Electrical previous year question papers so here it is for you:

1. The purpose of feedback transformer & diode in complementary commutated inverters is to-

2. In order to obtain static voltage equalization in series connected SCR’s connection r made of- (this question repeated) (i.e. 2 times same question Haaa)

3. In phase controlled rectification PF=

4. Why sector winding is used in synchronous motor?

5. A calculation of making current where MVA & KV was given.

6. The o?p voltage e1 & e2 of 2 full-bridge inverters added using o/p transformer. In order to eliminate 5th harmonic from o/p voltage, the phase angle between e1&e2 will be-

7. A single phase fully controlled line commutated ac-dc converter operates as an inverter when-

8. An SCR has half cycle surge current rating of 3000A for 50Hz. One cycle surge current will be. (double of that)

9. When compared to an symmetrical thyristor, the turn off time & reverse blocking voltage of an asymmetrical thyristor will be-

10. A step-up chopper is feed from an 220v dc source to deliver a load voltage of 66o v. If the non conducting time is 100micro-sec then reqd pulse width will be. (get duty cycle only)

11. There were some 5-6 numerical problems which I could not remember totally but they consist of firing angle & power transfer of inverter, SCR. Go llok for that.

12. Relay current setting & Ct ratio was given you have to find out Relay Pick up Current.

13. One question from Dc shunt motor- like a resistance is added of 4.5 ohm in series with arm where rest of arm is 0.5 ohm. Machine is supplied 220v. find out the null current.

14. In aptitude part see through series completion there was a 5-6 no of that.

15. No aptitude questing like avg, %, proff-loss, prob, etc.

16. Sentence correction 2-3.

17. Why rotor of SCIM is skewed?

18. Magnetostriction increases-

19. Good transformer oil contains how much amount of water in ppm?

20. Lightning over voltage create how much volt?

21. K/s(s+1)(s+5) then find out the value of K so that system become stable.

22. There was a question from definition of Nyquist criteria.

23. Standing done up to the frequency range of? (audio)

24. If a square waveform if given to the supply side of a 2wdg transformer its o/p waveform will be-

25. SC test done on transformer because-

26. If a transformer is operating in .8 PF lag & at efficiency of .9, if now P is .8 lead the efficiency will become.

27. Interpoles are connected for?

28. Dielectric strength of air-

29. A alternator is connected to a grid. Now its prime mover is go slow by ½. Change in its exiting current to held in synchronism.

30. Is the strength of capacitor in LPF is increased the op voltage will-

31. The voltage of a generator and an infinite bus are given 0.92, 10 deg & 1.0, 0 deg resp. the generator acts as a –

32. A wave will not experience any reflection when impedance of line is equal to- surge imp

33. Power transmitted is related to system voltage as-

34. Delay creator ckt name (multivibrator name actually)

35. In tachogenerator adjustment is done by-

36. Surge wave is attended by- (C,L,R)

37. There was 10 question related to measurement-

38. Read all electrostatic instrument related question from any competitive exam book.

39. Lowest reading in moving iron meter is-

40. In galvanometer damping is provided by-

41. In electrodynamic meter a battery & a resistance is provide for-

42. Megger is used for-

43. A question like an ac is applied against a moving coil meter it will reads-

44. Rectifier type instrument measureswhat value – (Rms)

45. Advantage of electrostatic instrument is-

46. Creeping occurs because-

47. Why 2 holes are drilled oppositely in disc of energy meter.

48. Energy meter is a _____ type equipment (recording)

49. There was a question related to selection of a voltmeter based on accuracy-

50. Advantage of hay bridge over anderson bridge-

51. Inductance is measured by – (all the 3 bridge name) .

52. Potentiometer is which type of instrument-

53. Which type of motor is used in refrigerator?

54. Reflection coefficient based problem 1

55. Corona ’s advantage-

1 synchro tc and rx is

a ) two phase ac

b) three phase ac

c) dc only

d) none

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

3 G(s) = 10/S(S+2) then the natural frequency of this transfer function is

a) 3.146

b) 4

c) 5

d) 2

4 In TV video amplifier is used for =?

5) one block contain one of the R L C element then the frequency of that one is 1 MHZ when the capacitor C= 0.1 uf is added to that block then the frequency becomes 2 MHZ then what is the element inside the block at first time

a) resistor

b) inductor

c) capacitor with 0.5 uf

d) none of these

ans : b

6) For unit step input they gave the input G(S)= – — – – -,h(s)= ——-then he ask the steady state error for that transfer fn

7)Avalanche photo diode is used when compared to PIN diode bcz

a) larger band width C)——-

b) high sensitivity d) ——–

8) 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

9) ifthe output of the gate is always high then the gates applied to this logic are

a) NAND and EXOR

b) Nand and NOR

c) AND and XNOR

d) OR and XOR

Ans ) a

10) For the voltage series feedback he gave input resistance and A and beta value then find the output resistance ?

11)Signal to noise ratio =15 db Bandwidth =4KHZ then the channel capacity -?

Ans : C= B Log (1+ s/n) =16 log 2

12 ) Four messages are given like this 0.5,0.25,0.125,0.125 ,entrophy value is =?

Ans: Entrophy= Avg of all informations

13) Thermal Run away is not possible in FET bcz the flow of

a) minority careers c) _____

b) Transconductance d) none

Ans : FET is unipolar so there are no minority careers .Thermal run away occurs only minority careers

14)Gm= 10 ,Rd =20k,Rl =10 find the amplification factor -=?

Ans = U= Gm Rd

15) Two ideal voltage sourd=ces resistors are connected in series ,power of that one is 4W ,If one of the sorce is active other resistors are shorted .Calculate the power when both are active +/

a) 0W,8W

b) 8W,6W

c) 4W,0W

d) None

16) A TV braod cast tx uses which type of antenna =?

a) parabolic antenna b)=—

c)—– d) —–

ans : a

17) Electric field and equi potential lines are

a) parallel to each other

b) In Quadrature

ans : b

18 ) L1= —– , L2 = —- k= _—- then mutual inductance of the coil is =?

Ans : M=ksquare root of L!and L2

19 ) one cube some is there to find out the how many number of cubes are having single side ?

20)Two qs in verbal are —– two statements are given for that the relation btwn those two

1. When the temperature of the room increased then the energy of semiconductor…

2. Power diode is generally made from: – Silicon/Germanium/Both/None of these

3. Thermionic Emission of electron is due to………….

4. 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

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

6. Which coupling gives the higher gain in case of amplifier: -
a) Capacitor coupling b) Impedance coupling c) Transformer coupling

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

8. A narrowband amplifier has a band pass nearly…………of central frequency:-
a) 33.3% b) 10% c) 50%

9. Frequency of wein bridge oscillator

10. Phase shift oscillator consists: -
a) RL b) RC c) RLC

11. Crystal oscillator frequency is very stable due to:-

12. Multivibrater Produces: -
a) Sine wave b) Square wave c) Smooth wave d) sawtooth

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

14. 10 in BCD: -
a) 10100 b) 1100 c) 010111 d) None of these

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

16. In 3-Phase full converter, the output during overlap is equal to……………..

17. Addition of indium in semiconductor crystal makes: -
a) PNP b) NPN

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

19. Ripple factor of half wave rectifier: -
a) 1.21 b) 0.48 c) 0.5

20. Efficiency of half wave rectifier: -

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

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

22. High cutoff frequency: -
a) CB b) CC c) CE

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

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

25. When modulation frequency is doubled, modulation index also doubled in case of: -
a) FM b) PM c) AM d) PM & FM

26. Term ’Noise temperature’ is used for

27. Video detector used in TV receiver is a….
a) Diode detector b) Ratio detector c) Phase detector

28. Which isn’t directly operated from mains: -
a) Half wave rectifier b) Centre tap rectifier c) Bridge rectifier d) Voltage doubler

29. In 3-Phase half wave rectifier each diode conducts for duration of: -
a) 30 Degree b) 45 Degree c) 60 Degree d) 180 Degree

30. If number of phase in a multiphase rectifier increased then: -
a) Output increased b) Output decreased c) Output smooth d) No change

31. Which output requires minimum filtration: -
a) Half wave rectifier b) full wave c) SCR half wave rectifier d) Voltage doubler

32. Identify the under circuit
a) Low pass filter b) High pass filter c) Band pass filter

33. Transistor is a following operated device: -
a) Low voltage & low current device
b) Low voltage & high current device
c) Low current & high voltage device
d) High current & high voltage device