| 69823

HAL sample test paper

69823

HAL sample test paper

HAL Sample Test Paper

1. When length of a wire increases its resistance
a. doubles
b. half
c. remains same
Ans: ( a )

2. When a 50 Hz ,6-pole Induction Motor runs at 975rpm,the rotor emf frequency is
a. 12.5Hz
b. 1.25Hz
c. 4Hz
Ans: ( b )

3. When a 6 pole 50Hz Induction Motor runs at 1450 rpm , itâs working mode is
a. motoring
b. braking
c. generating

Ans: ( a )

4. Slips for Different modes of operation of Induction Motor are
answer: motoring -01

5. Damping ratio ( ? ) is 0.75, natural frequency is 12 rad/s are given & asked to find peak time

6. In electrodynamo-meter type wattmeter
a. pressure coil is made fixed
b. current coil is made fixed
c. both the coils are made fixed
Ans: ( a )

7. In flux meter control torque is produced by
a. weights attached to it.
b. Springs
c. No control torque is there
Ans: ( c )

8. One question regarding hot wire instrument

9. In MI meters deflecting torque is proportional to
a. square of the current
b. square of the voltage
Ans: ( a )

10.In 3-F system total power is given by
a. v3VLILcos F
b. 3VLILcos F
c. VLILcos F
Ans: ( a )

11.From supply one 3-F step-down transformer is drawing 10 A, the secondary current will be minimum when the transformer is
a. star-delta
b. delta-star
c. delta-delta
d. star-star
Ans: ( b )

12.Transformer rating is expressed in
a. KVA
b. KVAR
c. KW
Ans: ( a )

13.Manganin is a
a. Insulator
b. Semi-conductor
c. Alloy

14.Dual scope oscilloscope has
a. two separate horizontal and two separate vertical plates
b. one horizontal and two separate vertical plates
c. two separate horizontal and one vertical plates
d. one horizontal and one vertical plates

15.Standard Cell voltage is measured by
a. MI meter
b. MC meter
c. Potentiometer

16.The input resistance of the CRO is of the order of
a. tens of ohm
b. mega ohm
c. kilo ohm
d. fraction of an ohm
Ans: ( b )

17.Errors are introduced in Wheatstone bridge due to
a. lead resistance
b. contact resistance
c. some thing is given
d. all of the above

18.HRC fuse and circuit-breaker combination is used CB operates for
a. low over-load currents
b. high over-load currents
c. combination is never used

19.G(s) = K / s(s+5)(s+1) is given to find the value of K for stable operation

20.By increasing gain of the system root locus will
a. moves away from poles
b. moves away from zeros
c. crosses imaginary axis
Ans: ( a )

21.When the load current is high while measuring power using wattmeter
a. current coil is connected near load
b. pressure coil is connected near load

22.C = 0.01ÂµF and L = 1 mH and current is 10 A and asked to find the voltage drop

23.Transmission line is terminated by R and no reflection is there , then the value of R is
_________
Ans: 400 ohm

24.One question regarding shunt ohm-meter and seriea ohm-meter

25.Inverted V curves are drawn between ________

Ans: field current Vs power factor

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

2) In order to obtain static voltage equalization in series connected SCRâs connection r made of- (this question repeatedquestion)

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 oop 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.

17) Why rotor of SCIM is skewed?

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 Â½. 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 â

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 â (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) Coronaâs advantage-