Electrical new- August & September attempt (kindly correct the options or questions if incomplete and add any questions left)1. If in a motor reactive coil is placed then what is the advantage?

2. If thyristor is used in place of starter (mcq)

a. Cost decreases

b. Space decreases

c. As load increases frequency increases uniformly

d. Maintenance decreasesBCD3. If fuse is placed in parallel with SCR circuit then? Ans- to protect the SCR4. If in a circuit direction of magnetic lines of force becomes opposite then?

5. In relation to Electric motor stator which statement is true?

6. For incoming generator which of the statements are true?

a. If Incoming generator voltage is increased then it will have motoring effect.

b. If voltage is decreased then it will cause black out.c. If frequency do not match then it will run slowly.d. If frequency do not match then will run fast.B7. Pure inductive power is called

a. Reactive powerb. True power

c. Set powerA8. Zener diode is used as

a. Voltage regulator

b. RectifierA9. How with the help of pressure electrical signal is converted

i. Transducer

ii. Tuctile sensor

iii. Reactor

iv. Dont remember

a. Only i

b. I & ii

c. Only iv

d. Ii & ivA10. Which statement is true in relation to AUTO TRANSFORMER? (mcq)a. More effective than conventional transformer

b. Any fractional voltage can be appliedc. Can be used both for A.C and D.C

d. Less excitation needed.

e. Voltage regulation of autotransformer is much betterf. Its size is relatively very smaller.

ADEF11. For a turbo electric propulsion generator which can be fitted?a. Co2 system

b. Moisture something

c. Stator winding temperature sensor

d. AllD12. Class B AMPLIFIER advantage? All13. Regenerative breaking of motor? (mcq)ans- aec < all option are not known>

a. If motor stops then we shut off the power.

b. It converts kinetic energy back to chemical energy.

c. Spring break

d. Current direction changes then it rotation direction changes.

14. How is natural cooling of transformer done?

a. Air blast

b. Oil cooling

c. Water cooling

d. NoneD15. If in a bulb number of electrons passed is 10^22 in 1hour and charge of each of e- is 1.6x 10^-19. Then find current?

Ans- 0.445 ( I = dq/dt)16. Atoms are bonded by?

a. Valence electronsb. Neutron

c. Proton

d. Not knownA17. Which statement is true for OVERCURRENT TRIP and FUSE?

a. Overcurrent trip acts on overload & fuse blows before that?b. Not knownA18. If V = 3v, R= 120ohms. Then find I in mili amp? Ans- 25

19. If ni-cd battery fully discharges then? Ans- ni(oh) forms on plates20. If in a grounded neutral system, a wire touches hull then? Ans- short circuit

21. A-AMPLIFIER power can be increased how? Ans-transformer coil added22. If in an electromagnetic coil current is then its energy stored will be? (E=1/2LI^2)a.

b.

c. Twiced. No changeA23. For half wave rectifier ripple factor is? ( for full wave- 0.482)

a. 1.41

b. 1.21

c. 131

d. 1.51B24. For soft stator and normal stator which of the statement is true?

25. In case of synchronization bulb status? Ans- 2bright ( connected in different phase), 1 dark (same phase)26. To satisfy amplification, transistor amplifier must satisfy?

a. Forward biasing of output circuit.

b. Reverse biasing in input circuit.

c. Operate at set pointd. AllC27. Which of the following are true for Thermistors (mcq)

a. Thermistors are semiconductors devicesb. In a Positive temperature coefficient (PTC) thermistors, resistance increases with temperature increase

c. Negativeve temperature coefficient (NTC) thermistors, can be used as replacement of fuse. (PTC)d. PTC thermistors can be used as resistance thermometers in low temperature environments. (NTC)e. NTC thermistors are generally used for monitoring coolant and engine lube oil temp in automobiles.ABE28. Which trip is present in emergency generator?

a. Over voltage trip

b. Under voltage trip

c. Over speed trip

d. NoneC29. Sine wave having RMS value=100v is superimposed with 50v D.C supply?

30. NER- what is true for high voltage circuit?

a. To limit max load current

b. Neutral earth resonance

c. Main switchboard earthed

d. Not knownA31. In Squirrel cage synchronous motor why squirrel cage is provided?

32. Which of the following is not self-starting motor? a. Squirrel cage motor

b. Synchronous motor

c. Induction motor

d. Split phase motorB33. In capacitor, energy stored is?

a. Potential energy

b. Electrostatic energy

c. Kinetic

d. Not knownB34. For t/c, leak current in P-N diode is produced by?

a. Heat energy

b. Chemical energy

c. Barrier potential

d. Not knownA35. Motor overhaul is to be done which statements are true?

a. Stator should be isolated

b. Tag on overall ship

c. Not knownA36. Electric motor stator- true statements? (mcq)

a. Generator used only with slip rings motors.

b. Freq. convertor can be used as startor.

c. Auto transformer act as rheostat stator

d. Not knownBC37. Limit switch (E/n throttle ---> limits pilot v/v moment38. Squirrel cage used in synchronous motor for?

a. Improving p.f

b. Uniform balancing

c. Just for starting

d. Not knownC39. wave rectifier efficiency? Ans- 40.6%

40. Which of the following will prevent a DC generator from becoming motorized?

a. Overcurrent relay

b. Motorization trip

c. Reverse power relayd. Reverse current relayD41. For leading power circuits which of the following can be used?

a. Shunt capacitors only

b. Shunt reactors only

c. Either shunt capacitors or shunt reactors

d. Neither shunt capacitors nor shunt reactors

( for leading a ckt, shunt capacitor is used as it improves p.f ; for a leading ckt, shunt reactor to reduce p.f)B42. To repair a small electric motor which was submerged in saltwater, you should

a. Wash it with f.w and apply an external source of heat.

b. Renew the windings

c. Send to ashore to an approved service facility

d. Rinse all electrical parts with a carbon tetrachloride cleaning solvents and then blow dry the motor with compressed airA43. An operating characteristic appearing on the name plates of shipboard AC motor is ___________

a. Type of windings

b. Input kw

c. Temp rised. Locked rotor torqueC44. Fuses replaced in series with thermal trip type ckt breakers are used for?a. Time delay protection

b. Short ckt protection

c. Short duration surge protection

d. Sustained overload protectionB45. To prevent the race of DC series motor what arrangement should make?

a. Always start at heavy load (ANS)b. Use a strong series weak shunt compound DC motor

c. Use a weak series strong shunt compound DC motor

d. AllA46. Current applied to lead acid battery would lead to

a. Higher thermal voltage

b. Lower terminal voltage high charging

c. Increase generation of H2 gas (overcharge)d. Decrease in specific gravity of electrolyteD47. Across the line starters are used with AC motors to provide (DOL starter)a. Reduced starting current

b. Regulated starting current

c. High starting torque (ans)d. Controlled starting accelerationC48. In an earth neutral system, an earth fault will occur only

a. 1 fault in 1 line

b. 2 fault in two line

c. Two fault in 1 line

d. Dont knowA49. Which statement is true for any storage batterya. Amp hr efficieny of alkaline battery is high than lead acid battery

b. Watt hr efficiency of alkaline is more than lead acid battery

c. Alkaline battery can left in any state of charge or discharge (ans)d. AllAC50. Which of the following is true about star delta starters (mcq)a. Popular bcoz relatively inexpensive

b. Gives lower starting current than DOL

c. Can only be used with induction motor delta connected in supply voltage

d. Typically used to start the motor with lower voltage BD51. A half wave rectifier has a resistive load 500, rectifies alternating voltage of 65v, diode forward resistance is 50. Calculate peak value of current correct to 3 decimals. Ans- 0.167A ( 65root/500+50)52. Which of the following are true for shipboard storage batteries?a. Construction should be so as to prevent emission of spray

b. If voltage is above 200v insulation stands must be used

c. The deck below the cells should be protected with acid resisting or alkaline resisting materials d. Battery banks above 2 kw should be kept in battery room onlye. Emgy batteries should never be stored in battery roomABC53. In common collector transistor collector amplifier voltage gain

a. Cannot exceed unity (single choice)b. Depends on output impedance

c. Depends on output signal d. Always constant (o/p equal to i/p Vg)A D54. Which statement is true for reactor starter for electrical motor

a. Minimum reduction in starting torque available (large reduction)b. Starting current is limited in proportion to voltage

c. Advantage is low cost

d. Coil with iron core is connected in parallel with motor during starting (series)BC55. Which statement is true about any soft starters used in electrical motor

a. Soft starters are based on semiconductors

b. Used to control the stopping of motor (soft stop)c. Use of soft starters initially result in lower motor torque

d. Soft starters progressively increase motor voltage which course torque or current peak (course=progress)(thesoft starter progressively increasesthemotor voltageso that themotorbecomes strong enough to accelerate the load to rated speed without causingtorque or current peaks.)

ABC56. Voltage generator by most AC generators is fed from the machine to the bus by means of

a. Brushes on commutator

b. Brushes on slip ringsc. Slip rings on commutator

d. Direct connection from statorD57. Which of the following are true about a temp measuring ckt employed in in a data logger system1. A Wheatstone bridge can be used in conjunction with a Wheatstone bridge induction thermometer

2. Thermometer is energized using a constant current source and voltage developed is measured in potentiometer type method

3. Inductance of thermometer will change with change in temp

a. 1 only

b. 2 only

c. 1 & 2 only

d. 1 & 3 only

e. 2 & 3 onlyE58. Dis advantage of ward Leonard system (mcq)

a. Motor generator set requires lot of space

b. Overall efficiency of the system is low especially when lightly loaded

c. System operates in very narrow speed range

d. Requires high maintenance

e. Speed regulation is difficult to achieve as motor acceleration is uniform

f. expensiveABDE

59. Electrons and protons having same momentum travel in uniform mag. Field flux density is B. mass of elec Me, mass of proton is Mp. Re is radius of e- and Rp of proton. Calculate Re/Rp upto two decimal. Ans- 0.02

60. Which of the following are benefits of modifying ward Leonard control system by replacing motor set with a thyristor speed controller a. Enhanced speed regulation by making the motor acceleration uniform

b. Increases efficiency of system especially lightly loaded

c. Reduces the overall cost d. Reduces system maintenance

e. Increases operating speed range of system

f. Reduces overall space requiredBCDF61. Arrange the following in correct sequence foe achieving correct KW sharing when an AC generator is paralleled with live bus bar and generator has some owe factor as others in system

1. Synchronize the incoming generator in terms of voltage, frequency and phase.

2. Trim voltage of the machine which has/ have lower load current to increase excitation

3. Increase speed on incoming machine while lowering than that of others connected to system

4. Adjust machine voltage to keep overall system efficiency ready.

5. Adjust the governor control switch on main switch board to increase the fuel to its prime mover

a. Adc

b. Aebc

c. Aecb

d. Aec

e. Adbc

f. acbdD62. which of the following is true for syncronoscope (mcq)a. one of the coil in the armature is fed through a capacitor while other is through resistance

b. the coil produces a three phase rotating fieldc. the rotating armature has two coils windings perpendicular to each other.

d. The field produces by the coils rotates the magnetic armature pointer at a speed relative to the frequency of the bus bar supply

e. The coils produce a single phase rotating field.CDE63. Motor having rheostat in motor circuit to vary speed in cell (ans is brushed DC motor)a. Squirrel cage motor

b. Regenerating breaker motor

c. Wound round induction motor

d. Synchronous motorC64. Mercury filled thermometer should never be used to determine the temp of the battery electrolyte bcoz accidental breakage of thermometer can cause

a. Severe sparking and explosions

b. Rapid oxidation of battery plates

c. Contamination of the electrolyte

d. Corrosion of battery terminalsA65. An amplifier is said to suffer distortion when its output isa. Low

b. Different from input

c. Noisy

d. Larger than is inputB66. Which of the following is true with regard Tobi metallic strip(mcq)

a. Generally used for temps sensing

b. During normal than higher than normal current, bimetal strip will bendc. Used for voltage regulation

d. Used as thermal elements in over current protection relaye. Used for power controlD67. What is the value of z in series ckt where xl= 9 ohms xc= 5 ohms r= 8 ohms..(1 decimal) = 16.12 ohm68. What happens when battery is excess charged?

A. Electrolyte decreases

B. Gassing increases

C. Dont remember

D. Dont rememberB69. Which statements are true/

a. Rheostat stator have slip rings (0nly rotor)b. Frequency convertor can be used as stator

c. Soft stator are made of semiconductor

d. Reactance stator is used are of low costBC70. Emergency over speed tripa. Load increases

b. Test switch

c. Tachometer to increase .

d. Dont remember

B6. which of the following is true abt star delta starters(mcq)

a. popular becoz relatively inexpensive

b. gives lower starting current than dol c. can only b used with induction motor delta connected in the supply voltage d. tpically used to start the motor with lower voltageBCD