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HPCL Test Paper - Electrical & Electronics Engineering
1. Choose which of the below mentioned stands true for its justification.
a. A transparent latch consists of a D â flip flop
b. A flip â flop is used to store 1 â bit of information
c. Master slave flip flop is used to store 2 bits of information
d. Race around condition occurs in JK flip flop when both the inputs are 1
2. Choose the correct option to identify the fastest read/writable memory?
a. Flash
b. PROM
c. EEPROM
d. None of the above
3. Which logic is used by odd parity generator?
a. Analog
b. Sequential
c. Digital
d. None of the above
4. If you have to implement AB+CD+EF, how many NAND gates will be required to do so?
a. 2
b. 1
c. 3
d. 4
5. State the value of Aâ+1.
a. 1
b. A
c. Aâ
d. None of the above
6. According to Boolean Algebra what is the value of 1+A+B+C
a. A+B+C
b. 1
c. A
d. None of the above
7. How many number of 1âs are there in the binary expression â 162*9+162*7+16*5+3?
a. 23
b. 4
c. 6
d. 10
8. Choose the correct alternative that is used as a data selector.
a. Decoder
b. Modulator
c. Encoder
d. Demodulator
9. Which transistor will you use in enhancement mode?
a. UJT
b. MOSFET
c. JFET
d. NPN
10. Which of the following option consist of high cut â off frequency?
a. CE
b. CB
c. CC
d. None of the above
11. What is the largest negative number be represented with 8 bits in 2âs compliment representation?
a. -127
b. -256
c. -255
d. -128
12. State the range of generation voltage.
a. Between 400 KV and 700 KV
b. Between 11 KV and 33 KV
c. Between 132 KV and 400 KV
d. None of the above
13. Choose which of the following option falls true for hysteresis motor.
a. Needs Dc excitation
b. Is not a self â starting motor
c. Is a constant speed motor
d. Cannot be run in reverse speed
14. Which heating method is independent of supply frequency?
a. Dielectric heating
b. Electric arc heating
c. Induction heating
d. Electric resistance heating
15. What is the power factor of a squirrel cage induction motor?
a. Low at heavy load only
b. Low at light load only
c. Low at light and heavy load only
d. Low at rated load only
16 .Choose the correct option which uses direct inward dialling as one of its feature.
a. VPN
b. PBX
c. PSTN
d. EPABX
17. Choose the correct option for identifying the two windings of a transformer?
a. Not linked at all
b. Conductively linked
c. Electrically linked
d. Inductively linked
Fill in the blanks
18. In a stepper motor the angular displacement _______
a. It cannot be used for positioning of work tables and tools in NC machine
b. Can be precisely controlled
c. It cannot be readily interfaced with micro - computer based controller
d. The angular displacement cannot be precisely controlled
19. The purpose of inducing emf in the primary of a transformer ______
a. Leads the flux by 90 degree
b. Lags behind the flux by 90 degree
c. Is in phase with the flux
d. Is in phase opposition to that of flux
20. Which motor will you choose which can operate in both lagging as well as leading power factors?
a. Synchronous motor
b. Squirrel cage motor
c. DC shunt motor
d. Wound rotor induction motor
21. What will be the voltage regulation of a full load and 0.80 power factor lagging load transformer when a two winding single phase transformer has a voltage regulation of 4.5% at full load and unity power factor?
a. 4.5% or more
b. Less that 4.5%
c. 4.5%
d. More than 4.5 %
22. What is the armature mmf in a D.C machine?
a. Rotating w.r.t field
b. Stationary w.r.t armature
c. Rotating w.r.t brushes
d. Stationary w.r.t field
23. What will be the output of a step â input is given to an op â amp integrator?
a. Rectangular wave
b. A ramp
c. A sinusoidal wave
d. A triangular wave with DC bias
24. What will be the output voltage of a transformer if it is primarily energised from a square wave voltage source?
a. A pulse wave
b. A square wave
c. A sine wave
d. A triangular wave
25. How will a motor react if salient pole is running synchronously at no load and its field current is switched off?
a. Come to a halt
b. Continue to run at a speed slightly less than the synchronous speed
c. Continue to run at synchronous speed
d. Continue to run at a speed slightly more than the synchronous speed
26. Why should you always start the D.C series motor with load?
a. It will fail to start
b. It will not develop high starting torque
c. At no load, it will rotate at dangerously high speed
d. All the above mentioned are true
27. Which is the most suitable servomotor for low power application?
a. A DC shunt motor
b. A DC series motor
c. An AC two â phase induction motor
d. An AC series motor
28. What will you use to take out the current from the stator of an alternator?
a. Commutator segments
b. Slip rings
c. Carbon brushes
d. Solid connections
29. When will be the voltage zero in a transformer?
a. Leading p.f
b. Zero p.f leading
c. Unity p.f
d. Lagging p.f
30. In audio amplification, which distortion will you least object?
a. Frequency
b. Harmonic
c. Intermediation
d. Phase
31. When the relative speed between the magnetic fields of stator and rotor does is zero under steady state operation?
a. Synchronous machine
b. DC machine
c. Single phase induction machine
d. 3 phase induction machine
e. All of the above are true
32. What shall be the secondary output voltage if the primary winding of a 220/6V, 50 Hz transformer is energised by a 110V, 60 Hz supply?
a. 3.0 V
b. 3.6 V
c. 2.5 V
d. 6.0 V
33. Choose the correct option to identify whose protection is taken care by âwho relayâ?
a. Long lines only
b. Short lines only
c. Any line
d. Medium lines only
34. What is the mechanical power developed in terms of air gap power Pg in a 3 phase induction motor running at slip âsâ?
a. (s-1) Pg
b. Pg/1-S
c. 1-SPg-Answer
d. S.Pg
35. The electromagnetic torque developed in proportional to what in a D.C series motor?
a. 1a
b. 12a-Answer
c. 1/1a
d. 1/12a
36. What is the frequency of the rotor current in a 3 phase 50 Hz, 4 pole induction motor at full load?
a. 2 Hz
b. 20 Hz
c. Zero
d. 50 Hz
37. What does the damper winding produce when a synchronous motor is running at a synchronous speed?
a. Eddy current torque
b. Damping torque
c. No torque
d. Torque aiding the developed torque
38. What is the unit of magnetic flux density?
a. Bohr
b. Weber/sec
c. Gauss
d. Tesla
39. Define bistable multi â vibrator.
a. Saw tooth wave generator
b. Free running oscillator
c. Crustal oscillator
d. Triggered oscillator
40. Choose the correct mean by which the speed and torque of induction motor can be varied?
a. Frequency control
b. Stator voltage control
c. Rotor voltage control
d. All of the above
