1. Which of the following statements is true concerning a poly-phase synchronous propulsion motor? A. The motor is started as an induction motor.
B. Resistance is gradually added to the rotor circuit. C. The starting current is held below the rated curren t. D. The field winding is energized for starting purposes only.
ANS- A 2. When reading electrical motor controller diagrams, it helps to know that _____
A. current paths in the control circuit are drawn as heavy lines and in the power circuit as lighter lines B. current paths in the power circuit are drawn as heavy lines and in control circuit as lighter lines C. circuits subject to 500 volts or greater are drawn as heavy lines and below 500 volts as lighter lines D. circuits subject to 500volts or greater are drawn as light lines and below 500 volts as heavy
ANS- B 3. Alternating current circuits develop resistance, inductance and capacitance. The inductance of a coil is expressed in A. ohms B. mhos C. henrys D. farads
ANS- C 4. Large cable sizes are formed as individual conductors that may be comprised of several smaller strands to
A. obtain the flexibility required for easy handling B. reduce the overall weight of the wire run C. reduce the number of supports needed for a horizontal overhead run D. all of the above
ANS- A
5. Which of the following is having Di-Electric Constant 80?
A. Air
B. water
C. Mica
D. Caster oil
ANS- B 6. Where a thermal-acting breaker is required to be used in an area of unusually high, low, or constantly fluctuating temperatures, an ambient compensating element must be used. This element consists of a
A. cylindrical spring on the contact arm B. conical spring on the contact arm C. second bimetal element
D. second electromagnet
ANS- C 7. Which of the following precautions should you take when securing propulsion generators and motors for an extended period of time?
A. Disconnect the brush pigtails from their contacts and circulate air throu gh the units. B. Disconnect the brush pigtails from their contacts and discharge carbon dioxide into the units to keep them dry. C. Lift the brushes from commutator collector rings and use the bu ilt-in heater to prevent moisture accumulation. D. Lift the brushes from commutator collector rings and circulate cool dr y air through the units.
ANS- C 8. The direction of magnetic flux changes when the direction of current is reversed .
a. True b. False
ANS- A
9. In a Transistor (If Multi choice add option A) A. B. C. D.
PNP and NPN are two basic types Emitter, Collector and Base are the basic Elements . Collector separates Base and Emitter Emitter separates Base and Collector
ANS- B 10. In a P-Type Semiconductor, the majority current Carriers are________
ANS- holes
11. In a Control Loop S ystem, having Zero (0) Positive Real Values are c alled
…………..
ANS - Phase current or Error signal 12. If a Motor is not rotating in the E/R, you will carry out the following Checks (multiple choice, 3 Questions of same type but Options were different)
A. Check for the isolation B. Rotate the Coupling with your hand C. Check for the Circuit breaker
D. Remove the fuses E Look for the Overload Trip F. Visually inspect the motor terminals G. Visually Inspect the Starter Terminals H. Carry out Infinite Resistance Test
13. Resistance of a wire is increased if the Length is________ and Area is _________
ANS INCREASED, INCREASED, DECREASED refer R= refer R= specific resistance * length / Area –
14. Arrange the following in Increasing Order of their Doping Strength. A. Collector, Emitter, Base B. Base, Emitter, Collector C. Emitter, Base, Collector D. Emitter, Collector, Collector Base, Collector, Base
Answer is-Base, collector, emitter
15. Which of the listed precautions should be taken when cleaning the internals of a motor with compressed air?
A. Open the machine on both ends so as to allow the air and dust to escape. B. Be certain that the circuit breaker is opened and tagged on the feeder panel.
C. Be certain that the air is clean and as dry as possible. pos sible. E. Ensure that the fuse in the motor is removed
ANS- ABC
16. A molded-case breaker provides protection against short-circuits by using a/an A. Shading coil. B. Arc quencher. C. Electromagnet. D. Holding coil.
ANS- C 17. PN diode advantage over vacuum diode? (a)Longer Life, b) No warm up time c) Less delicate d) All of the above
ANS- D 18. IN SQUIRREL CAGE INDUCTION MOTOR SPEED DEPENDS UPON?
ANS- Speed of the rotating stator field. 19. WHAT IS PIV
ANS- PEAK INVERSE VOLTAGE 20. WIRES WHY MULTIPLE STANDARD
ANS- Flexibility 21. Tightly knit metal braid wire can be used with a printed circuit board when
ANS- DESOLDERING COMPONENTS IN THE CKT 22. Time delayed or delayed action-type fuses are designed to _____________.
(A) Prevent grounds in branch circuits (B) prevent opens in motor circuits (C) permit momentary overloads without melting (D) guard lighting and electronic circuits
ANS- C
23. Silicon diodes designed for a specific reverse breakdown voltage, become useful as an electronic power supply voltage regulator, called _____________
(A) Tunnel diodes (B) hot-carrier diodes (C) compensating diodes (D) Zener diodes
ANS- D 24. Which of the following statements best describes the material known as varnished cambric?
(A) Felted asbestos sealed with varnish. (B) Cotton cloth coated with insulating varnish. (C) Rubber insulation coated with a layer of tin. (D) Paper impregnated with mineral oil, specially wrapped with nonmetallic tape, and coated with varnish.
ANS- B
25. A synchronous motor maintains synchronism with the rotating field because
(A) Field strength varies directly with rotors lIp (B) DC current applied to the rotor coils cau ses the rotor magnets to lock in with the rotating flux of the stator (C) the stator poles are dragged around due to the flux created by the excitation current (D) the stator flux rotates in the opposite direction
ANS- B 26. The part of a fuse that melts and opens the circuit is made of
(A) Copper and antimony (B) Steel and Babbitt (C) Aluminum or beryllium alloy (D) Zinc or an alloy of tin and lead
ANS- D 27. The apparent power in inductive circuit
A. True power B. Lead C. Inductive D. Reactive
ANS- D
29. If current reverses, the magnetic field also reverses; true (or) false
a. TRUE b. FALSE
ANS- B 30. Break down diode
………………………….
ANS- ____ zener zener diode ___ diode ___ and___ avalanche avalanche diode ____ (reverse (reverse biasing)
31. Open loop function system having one zero with positive real value is called __________ phase function.
32. Semi conductors failed to over ove r current reason
and _________
………………………
ANS- low breakdown voltage 33. Which of the listed precautions should take while cleaning poly phase motor internals with compressed air? (Multiple ans)
A. Open the machine as both ends so as to allow the dust to escape B. Be certain that the circuit breaker is opened, tagged as the feeder panel C. Be certain that air is clean and as dry as possible D. Ensure that the fuse is removed
ANS- ABC
34. Which of the following capacitor is having highest dielectric constant?
A. Air gap B. Glass C. Paper D. Polyester
ANS- B 35. A delayed action fuse is most frequently used in which of the listed circuit?
A. Lighting circuit B. Motor circuit C. Electrical heater
D. Padar circuit
ANS- B 36. The current in a semiconductor is produced by
A. Electrons B. Neutrons C. Protons D. Holes
ANS- AD 37. If an intrinsic semiconductor is doped with a very small amount of boron then the extrinsic semiconductor set formed, the no. of electrons and holes will
A. Both decreases B. Increase and decrease C. Both increases D. Decrease and increase
ANS- D 38. Series RLC voltage or impedance totals must be calculate by
vectors.
………………….
ANS- Voltage 39. When the current through the coil of an electromagnet is reversed, the direction of magnetic field also reversed
c. TRUE d. FALSE
ANS- C 40. A poly phase motor driving an engine room pump fails to start, when trying to identify the cause of failure, which of the following steps are applicable. (Multiple choice)
A. Visually examine the motor for open circuit fault B. visually examine the starter for open circuit fault C. Reverse the direction of current for its working D. Perform the infinite resistance test
ANS- ABD 41. Which of the following physical character does around rotor induction motor posses that squirrel cage motor does not
A. Slip rings B. End rings C. A centrifugal clutch
D. End plates
ANS- A 42. Which of the following conditions will occur when solenoid coil burns out of a cargo winch with a electrical brake.
A. The brake will be set by spring force. B. The motor will over speed and burns out C. The load suspended by the cargo boom will fail D. Nothing will happen; the winch will continue to operate normally
ANS- A 43. A low voltage protection circuit is used in electric motor starting equipment to
A. Trip circuit contractor when the motor over speed due to low voltage B. Trip circuit contractor when the motor develops short circuit due to low voltage C. Allows the motor to restart automatically on restoration of voltage without manual resetting D. Prevent motor from restarting automatically
ANS- D
44. Determine the order of doping in transistor (from high to low)
A. collector, base, emitter B. Emitter, collector, base C. Base, emitter, collector D. collector, emitter, base
ANS- B 45. The opposition to the magnetic lines of force in magnetic is called
A. Resistance B. Reluctance C. Impedance D. Inductance
ANS- B 46. Factors varies potential of a PN junction depend on (multiple ans)
A. Type of semiconductor material B. Amount of doping C. Temperature D. None
ANS- ABC 47. A semiconductor is damaged by a strong current, because of (3 fill in the blanks)
ANS- _short circuit__, _overloading___, _overheating___.
48. A poly phase motor driving engine room pumps fails to start, checks
A. Insulation is open B. No restriction for movement of motor /pump C. Check overload relay trip D. Battery fully charged
ANS- ABC 49. Poly phase motor fails to start, precautions to take before checking
A. Isolate motor B. Remove fuse C. Post caution sign D. Ensure starter/motor terminals are live
ANS- ABC 50. Which of the following statement is true ( *)
A.PNP & NPN are different transistors B. Emitter, base and collector are basic elements C. Base separates, emitter, collector
ANS- ABC 51. Purpose of silicon control rectifier (*Multiple choice)
A. A.C to D.C convertor B. High voltage stand
ANS- AB 52. Generator paralleling
A. Incoming generator freq is less than bus bar frequency B. Incoming generator frequency is greater than
ANS- B
53. The value of open loop circuit 1.0 added with real value with curve -------------- phase (*qn,fill in the blank) 54. The induced voltage across a stationary conductor in a steady magnetic field is zero. ( *)
a. TRUE b. FALSE
ANS- A 55. Which of the listed devices is used to measure pressure and convert it to an electrical signal?
A. -Transducer B. -Reducer C. -Transformer D.
ANS- A
Rectifier Rectifier
–
56. In three phase electrical equipment, the immediate action in the event of fuse blowing in one of the phases would be
a. to replace with a fuse of correct rating b. to replace fuses on all three phases c. to try to repair the fuse d. to investigate the fault that led to blowing the fuse
ANS- B 57. Which of the capacity has dielectric constant of 1.0000?
a. air gap b. vacuum c. water d. electrolytes
ANS- B 58. Semiconductor forwarding current will be ________ if potential is overcome 59. A poly-phase motor driving an engine room pump fails to start. When trying to identify the cause of failure, which of the following steps are applicable? (Multi choice)
A. Visually examine motor for open circuit faults. B. Visually examine starter for open circuit faults. C. Reverse the direction of electrical supply to check if it works. D. Perform the infinite resistance test.
ANS- ABD 60. Tightly knit metal braid wire can be used with a printed circuit board when
A. Conductor flexibility is required B. De-soldering components in the circuit C. Electrically produced magnetic fluxes would cause inaccuracies in adjacent components D. Reactance in the circuit must be kept to a minimum
ANS- B
61. Which of the following statements represents an application of a silicon controlled rectifier?
A. To provide DC power for a main propulsion motor. B. For use as a voltage reference diode. C. For sensing flame in an automated burner. D. To eliminate power supply hum.
ANS- A 62. When paralleling an AC generator with live bus bars, which of the following precautions are applicable? (Multi choice)
A. Generator frequency should be slightly lower than bus bar frequency B. Generator frequency should be slightly higher than bus bar frequency C. Generator voltage should be in phase with bus bar voltage D. Generator voltage should be out of phase with bus bar voltage
ANS- BC 63. For leading power factor 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
ANS- B 64. A fuse that blows often should be replaced only with a fuse of
A. the recommended current and voltage rating B. higher current and voltage rating C. higher current and lower voltage rating D. lower current and higher voltage rating
ANS- A 65. Brushless generators are designed to operate without the use of
A. brushes B. slip rings C. commutators D. all of the above
ANS- D 66. Fuses placed in series with a thermal trip type circuit breaker are used for
A. Time-delay protection B. Short-circuit protection C. Short duration surge protection D. Sustained overload protection
ANS- B
67. In what range of voltages is the transistor in the linear region of its operation?
A. 0 < VCE < 0.7 V
B. 0.7 < VCE < 1.4 V C. 0.7 < VCE < VCE (max) D. 0 < VCE < VCE (max)
ANS- C 68. The greatest detrimental effect on idle electrical equipment, such as cargo pump motors, is the
A. Loss of residual magnetism. B. Absorption of moisture in the insulation. C. Insulation varnish flaking. D. Dirt collecting on the windings.
ANS- B 69. Ammeters and voltmeters used in sinusoidal AC power systems indicate which of the following values of the wave forms measured?
A. Peak value B. Root-mean-square value C. Average value D. Maximum value
ANS- B 70. Which of the following statements concerning analog and digital devices are correct?
A. The variables in digital systems are fixed qu antities and the variables in analog systems are continuous quantities. B. There are no basic differences between the two systems. C. Analog devices are superior in accuracy compared to digital devices. D. Operations in a digital device are performed simultaneously.
ANS- A
71. While starting a main propulsion synchronous motor, the ammeter pegs out at maximum and then returns to the proper value after synchronization. This indicates that the
A. Motor has started properly. B. Field windings are grounded. C. Slip rings are dirty. D. Power transmission cables are grounded.
ANS- A 72. When the current through the coil of an electromagnet reverses, the direction of the magnetic field also reverses.
a. True b. False
ANS- A
73. A magnetic blowout coil in a DC motor controller contact or functions to
A. Open contact rapidly. B. Reduce contact wear. C. Adjust opening spring tension. D. Provide "snap-action" in the contactor.
ANS- B 74. In a PNP transistor, the p-regions are
A. Emitter and Base B. Base and Collector C. Emitter and Collector D. Emitter, Base and Collector
ANS- C 75. In an n-type semiconductor, the minority carriers are (1) ___ _____
ANS- holes
76. In refer compressor what are the readings we are entering in logbook
A. S.W temp B. S.W Pressure C. Condenser temp D. Condenser leak
ANS- ABC 77. Breakdown diode on
……………………
ANS- zener effect and a valance effect
78. a material having good no. of electron in outer most shell is called a conductor 79. With reference to a Data Logger for a refrigeration system, which of the following parameters should be monitored?
A. Room temperature. B. Liquid Line temperature. C. Recharge temperature. D. Solenoid valve operation.
ANS- ABD 80. With reference to a Data Logger for a refrigeration system, which of the following parameters should be monitored?
A. Sea water temperature and pressure. B. Condensing temperature C. Refrigerant leakage D. Evaporating temperature
ANS- ABD 81. AC circuits possess characteristics of resistance, inductance, and capacitance.The capacitive reactance of a circuit is expressed in
A. ohms B. mhos
C. henrys D. farads
ANS- A
SECTION 2 DG SHIPPING
1. The shunt used in an ammeter should be connected in____________. (A) series with the load and in parallel with the meter movement (B) parallel (B) parallel with the load and in series with the meter movement (C) parallel (C) parallel with the load and in parallel with the meter movement (D) series with the load and in series with the m eter movement
ANS- A 2. Brushless generators are designed to operate without the use of ___________. (A) brushes (A) brushes (B) slip rings (C) commutators (D) all of the above
ANS- D
3. Which of the following following physical physical characteristics characteristics does a wound-rotor induction motor possess that a squirrel cage motor does not? (A) (B) (C) (D)
Slip rings End rings A centrifugal switch End plates
ANS- A
4. The current at which a magnetic-type overload relay tends to trip may be decreased by raising the plunger further in to the magnetic circuit of the relay. This action_________. (A) reduces magneticpull on the plunger and requires more current to trip the relay (B) reduces magnetic pull on the plunger and requires less current to trip the rela y (C) increases magnetic pull on the plunger and requires more current to trip the relay (D) increases magnetic pull on the plunger and requires less current to trip the relay
ANS- D 5. Protection against sustained overloads occurring in molded-case circuit breakers is provided by a/an _________. (A) over voltage release (B) thermal acting trip (C) thermal overload relay (D) current overload relay
ANS- B
6. Which of the listed logic gates is con sidered to be a BASIC building block b lock (basic logic gate) used in logic diagrams? (A) NAND (B) OR (C) NOR (D) All of the above.
ANS- B
7. When choosing a battery for a particular pa rticular application, major consideration should be given to the battery's (A) amp-hour capacity (B) terminal polarity (C) stability under charge (D) ambient temperature rise
ANS- A
8. The rated temperature rise of an electric motor is the _____________. (A) average temperature at any given latitude (B) normal temperature rise rise above the standard standard ambient temperature at rated load (C) average temperature rise due to resistance at 10% overload (D) permissible difference in the ambient temperature of the motor due to existing weather conditions
ANS- B 9. The electrical energy necessary to transmit a person's voice over a sound-powered telephone circuit is obtained from ____________. (a) dry cell batteries (b) the ship's service switchboard (c) the emergency switchboard
(d)
the speaker's voice
ANS- D 10. Local action in a nickel-cadmium battery is offset by _____________. (a) separating the positive and negative plates with plastic spacers (b) separating the positive and negative plates with resin impregnated spac ers (c) adding a small amount of lithium hydroxide h ydroxide to the electrolyte (d) trickle charging
ANS- D 11. The freezing point of the electrolyte in a fully charged lead-acid battery will be _____________. (a) higher than in a discharged battery (b) lower than in a discharged battery (c) the same as in a discharged battery (d) higher than in a discharged battery, but the specific gravity will be less
ANS- B 12. What is the maximum allowable primary current of a 2 KVA step-down transformer with a four to one turns ratio if connected across a 440 volt line? (A) 1.1 amps (B) 4.5 amps (C) 18.1 amps (D) 27.7 amps
ANS- B 13. Which of the following represents the accepted method of cleaning dust and foreign particles from electrical equipment while limiting damage to electric components? (A) (B) (C) (D)
Carefully wiping off the components with a soft co tton rag. Blowing a high velocity stream of compressed air rapidly across the component Using a vacuum cleaner to remove debris from the components. Using carbon tetrachloride as a cleaning solvent to clean the components.
ANS- C 14. Regarding an AC generator connected to them am electrical bus; as the electric load and power factor vary, a corresponding change is reflected reflected in the generator armature reaction. These changes in armature reaction are compensated for by the _____________. (A) governor speed droop setting (B) voltage regulator (C) balance coil (D) phase-balance relay
ANS- B 15. In an induction motor, rotor currents are circulated in the rotor by _______ (A) (B) (C) (D)
ANS- C
slip rings and brushes an armature and b rushes inductive reaction of the rotating stator field external variable resistors
16. An electrical device which prevents an action from occurring until all other required conditions are met is called a /an ___________. (A) (B) (C) (D)
limit monitor modulator interlock
ANS- D 17. A circuit breaker and a fuse fuse have a basic similarity in that they both _______ (A) (B) (C) (D)
can be reset to energize the circuit should open the circuit when overloaded will burn out when an over current flow develops all of the above
ANS- B 18. The electrolyte in a lead-acid storage battery consists of distilled water and _____________. (A) (B) (C) (D)
hydrogen chloride calcium chloride sulfuric acid muriatic acid
ANS- C 19. The full torque electric brake on an electric cargo winch functions to _____________. (A) act as a backup brake in the event the mechanical brake should fail (B) automatically hold the load as soon as current to the machine is shut off (C) automatically govern the lowering speed of the load (D) automatically govern the hoisting speed of the load
ANS- B 20. When troubleshooting most electronic circuits, "loading effect" can be minimized by using a voltmeter with a/an ___________________. (A) input impedance much greater than the impedance across which the voltage is being measured (B) input impedance much less than the impedance across which the voltage is being measured (C) sensitivity of less than 1000 ohms/volt (D) sensitivity of more than 1000 volts/ohm
ANS- A 21. An electric tachometer receives the engine speed signal from a _______________. (A) small generator mounted on the engine (B) bimetallic (B) bimetallic sensing device (C) stroboscopic sensing device (D) vibrating reed meter generating a voltage proportionate to engine speed
ANS- A 22. A three-phase alternator is operating at 450 volts with the switchboard ammeter indicating 300 amps. The kw meter currently indicates 163.6 KW, with a power factor of 0.7. If the power factor increases to 0.8, the KW meter reading would increase by ____________. (A) 17.8 KW (B) 23.4 KW (C) 30.6 KW (D) 37.8 KW
ANS- B
23. A semiconductor that decreases in resistance with an increase in temperature is known as a ___________. (A) resistor (B) thermistor (C) diode (D) thermopile
ANS- B 24. The shunt used in an ammeter should be connected in____________. (A) series with the load and in parallel with the meter movement (B) parallel (B) parallel with the load and in series with the meter movement (C) parallel (C) parallel with the load and in parallel with the meter movement (D) series with the load and in series with the meter movement
ANS- A 25. An operating characteristic appearing on the name plates of shipboard AC motors is _____________. (A) the type of winding (B) input kilowatts (C) temperature rise (D) locked rotor torque
ANS- C 26. Low horsepower, polyphase, induction motors can be started with full voltage by means of ___________. (A) compensator starters (B) autotransformer starters (C) across-the-line starters (D) primary-resistor (D) primary-resistor starters starters
ANS- C 27. Moisture damage, as a result of condensation occurring inside o f the cargo winch master switches, can c an be reduced by __________________. __________________ . (A) installing a light bulb in the pedestal stand (B) coating the switch box internals with epoxy sealer (C) venting the switch box regularly (D) using strip heaters inside the switch box
ANS- D 28. Where a thermal-acting breaker is required to be used in an area of unusually unusu ally high, low, or constantly fluctuating temperatures, an ambient compensating element must be used. This element consists of a ______________. (A) cylindrical spring on the contact arm (B) conical spring on the contact arm (C) second bimetal element (D) second electromagnet
ANS- C 29. Which of the following statements represents an application of a silicon co ntrolled rectifier? (A) To provide DC power for a main propulsion motor. (B) For use as a voltage reference diode. (C) For sensing flame in an automated burner. (D) To eliminate power supply hum.
ANS- A 30. The electrolyte used in a nickel-cadmium battery is distilled water and ______________. (A) diluted sulfuric acid
(B) potassium (B) potassium hydroxide (C) lead sulfate (D) zinc oxide
ANS- B 31. Which of the damages listed can occur to the components of a winch master control switch, if the cover gasket becomes deteriorated? (A) Overheating of the winch motor. (B) Contamination of lube oil. (C) Sparking at the winch motor brushes. (D) Rapid corrosion of switch components.
ANS- D 32. An accidental path of low resistance, allowing pa ssage of abnormal amount of current is known as a/an ____________. (A) open circuit (B) short circuit (C) polarized (C) polarized ground (D) ground reference point
ANS- B 33. A resistance in a circuit of unknown value valu e is to be tested using the voltmeter/ammeter vo ltmeter/ammeter method. Therefore, the meters should be connected with _____________. (A) both (A) both meters in series with the resistance resistance (B) both (B) both meters in parallel with the resistance (C) the ammeter in series and the voltmeter in parallel pa rallel with the resistance (D) the ammeter in parallel and the voltmeter v oltmeter in series with the resistance
ANS- C 34. SOLAS regulations state that a normal source for emergency loads and power on a cargo vessel must be supplied from ____________. (A) emergency generator supply to the emergency switchboard (B) emergency generator supply to the main switchboard (C) battery (C) battery supply to the main switchboard (D) ship's service generator via the emergency switchboard
ANS- D 35. A storage battery for an emergency lighting and power system must have the capacity to _____________. (A) close all watertight doors twice (B) open all watertight doors four times (C) open and close all watertight doors in six consecutive cycles within a 20 second period (D) none of the above
ANS- A 36. SOLAS regulations require emergency diesel engine starting systems to have sufficient capacity to provide power for at least ____________. (A) three continuous starting sequences (B) six consecutive cranking cycles (C) nine repeated starts under load (D) twelve cranking periods of 5 seconds
ANS- B
37. Which of the following statements is a Safety regulation co ncerning emergency generator diesel engines? (SOLAS / Cargo Ship Safety Construction Ru les) 0 (A) The fuel must have a flash point p oint not less than 75 F. (B) Emergency diesel engines must be capable of operating under full load in not less than 30 seconds after cranking. (C) The starting battery must produce 12 consecutive cranking cycles. 0 (D) Emergency diesel engines must operate satisfactorily up to a 2 2.5 list.
ANS- d 38. If an AC motor is started and produces 25 horsepower, the kW meter reading will increase b y ___________. (A) 18.65 kW (B) 25.65 kW (C) 30.65 kW (D) 37.65 Kw
ANS- a 39. While on watch in the engine room at sea with only one ship's service shaft generator on line, the entire plant suddenly blacks out without warning. After restoring power, the cause for this casualty could be attributed to which of the following faults? (A) The micro switch at the generator speed trip vibrated open, allowing the main breaker to open via the under voltage trip. (B) Someone pushed the trip button to the "shore power" breaker. (C) The main air compressor suddenly stopped. (D) The standby generator started automatically and became motorized.
ANS- A 40. The function of a rectifier is similar to that of a _ ______.
(a) (b) (c) (d)
trap regulating valve check valve Filter
ANS- C 41. The basic control action of a magnetic amplifier depends upon _____________. (a) variations in the load capacitance (b) changes in inductance (c) type of core material (d) construction of the core Briefly Justify Your Answer
ANS- B 42. The seven segment arrangement for numerical display on consoles, test meters and other applications can be either ________________. (a) UJT or BJT (b) BCD or OCD (c) JFET or IGFET (d) LED or LCD
ANS- D 43. A silicon controlled rectifier (SCR) is a solid state device used to ch ange ________________. _______________ _. (A) DC to AC and control relatively low load current (B) AC to DC and control relatively high load current (C) DC to AC and control relatively high load current (D) AC to DC and control relatively low load current
ANS- B 44. Which of the following conditions will occur if the solenoid co il burns out on a cargo winch with an electrical brake? (a) The brake will be set by b y spring force. (b) The motor will over speed and burn up. (c) The load suspended from the cargo boom will fall. (d) Nothing will happen; the winch will continue to operate as usual.
ANS- A 45. Which of the listed battery charging circuits is used to maintain a wet cell, lead-acid, storage battery in a fully charged state during long periods of disuse? (a) Normal charging circuit (b) Quick charging circuit (c) Trickle charging circuit (d) High ampere charging circuit
ANS- C SECTION 3 FINALLY TAKEN FROM NET 1. The full torque electric brake on an electric cargo winch functions to
-act as backup brake in the event the mechanical brake should fail -automatically hold the load as soon as current cu rrent to the machine is shut off -automatically govern the lowering speed of the load
-automatically govern the hoisting speed of the load
ANS- B 2. An electric tachometer receives the engine speed signal from a
-small generator mounted on the engine -bimetallic sensing device -stroboscopic sensing device -vibrating reed meter generating a voltage proportionate to engine speed
ANS- A 3. A semiconductor that decreases resistance with an increase in temperature is known as a
-resistor -thermistor -diode -thermopile
ANS- B 4. The shunt used in an ammeter ammeter should be connected in
-series with the load and in parallel with the meter movement -parallel with the load and in series with the meter movement -parallel with the load and in parallel pa rallel with the meter movement -series with the load and in series with the meter movement
ANS- A 5. Brushless generators are designed to operate without the use of
-brushes -slip rings -commutators -all of the above
ANS- D 6. In the event of a power failure during cargo loading operations, the movement movement of an electric powered cargo winch will be stopped by
-a manual override switch -the weight of the load on the boom
-a spring set brake -a hand operated band brake
ANS- C 7. A ground can be defined as an an electrical connection between the wiring of a motor and its
-shunt field -circuit breaker -metal framework -interpole
ANS- C 8. The output voltage of a 440 volt, 60 hertz, AC generator is controlled by the
-prime mover speed -exciter output voltage -load on the alternator -number of poles
ANS- B 9. Which of the following statements represents the main difference between a relay and a contactor?
-Contactors control current, relays control voltage. -A relay is series connected and contactor is parallel connected. -Contactors can handle heavier loads than relays. -Contactors are made from silver and relays are made from copper.
ANS- C 10. The electrolyte used in a nickel-cadmium battery is distilled water and
-diluted sulfuric acid -potassium hydroxide -lead sulfate -zinc oxide
ANS- B 11. Which of the damages listed can occur to the components of a winch master control switch, if the cover gasket becomes deteriorated?
-Overheating of the winch motor. -Contamination of lube oil. -Sparking at the winch motor brushes. -Rapid corrosion of switch components.
ANS- D 12. An accidental path of low resistance, allowing passage of abnormal abnormal amount of current is known as a/an
-open circuit -short circuit -polarized ground -ground reference point
ANS- B 13. A resistance in a circuit of unknown value is to be tested using the voltmeter/ammeter method. Therefore, the meters should be connected with
-both meters in series with the resistance -both meters in parallel with the resistance
-the ammeter in series and the voltmeter in parallel with the resistance -the ammeter in parallel and the voltmeter in series with the resistance
ANS- C 14. A direct current passing through a wire coiled around a soft iron core is the description of a simple
-magnetic shield -electromagnet -piezoelectric device -electromagnetic domain
ANS- B 15. The use of four diodes, in a full-wave bridge rectifier circuit, will
-provide unidirectional current to the load -allow a very high leakage current from the load -convert direct current to alternating current -offer high opposition to current in two directions
ANS- A 16.A magnetic blowout coil in a DC motor controller contractor functions to
-open contact rapidly -reduce contact wear -adjust opening spring tension -provide "snap-action" in the contractor
ANS- B 17. The method used to produce electron emission in most vacuum tubes is known as
-photoelectric emission -secondary electric emission -cold cathodic electric emission -thermionic emission
ANS- D
18. Which of the listed devices is used to measure pressure and convert it to an electrical signal?
-Transducer -Reducer -Transformer -Rectifier
ANS- A 19. Grounds occurring in electrical machinery as a result of insulation failure are usually caused by
-deterioration due to age -excessive heat -vibration -all of the above
ANS- D 20.The amount of voltage induced in the windings of an AC generator depends on
-the number of conductors in series per winding -the speed at which the magnetic field passes across the winding -the strength of the magnetic field
-all of the above
ANS- D 21. The device that most commonly utilizes the principle of electromagnetic induction is the
-diode -transformer -transistor -rheostat
ANS- B 22. A tubular fuse should always be removed from a fuse panel with
-a screwdriver -a pair of insulated metal pliers -any insulated object -fuse pullers
ANS- D 23. One factor that determines the frequency of an alternator is the
-number of turns of wire in the armature coil -number of magnetic poles -strength of the magnets used -output voltage
ANS- B 24. Which of the motors for the devices listed below is fitted with an instantaneous overload relay?
-Fan -Pump -Winch -Machine tool
ANS- C 25. Which of the following statements concerning an analog device and a digital device is correct?
-The variables in digital systems are fixed quantities, and the va riables in analog systems are continuous quantities. -There are no basic differences between the two systems. -Analog devices are superior in accuracy compared to digital devices. -Operations in a digital device are performed simultaneously.
ANS- A 26. The number of cells in a 12 volt lead-acid battery is
-three cells -four cells -six cells -twelve cells
ANS- C 27. When choosing a battery for a particular application, major consideration should be given to the battery's
-amp-hour capacity -terminal polarity
-stability under charge -ambient temperature rise
ANS- A 28. Electrical leads and insulation on a motor motor should be painted with
-heat-resisting acrylic -heat-resisting aluminum -insulating varnish -insulating white lead
ANS- C 29. Voltage generator by most AC generators is fed from the machine to the bus by means of
-brushes on a commutator -brushes on slip rings -slip rings on a commutator -direct connections from the stator
ANS- D 30. A circuit circuit breaker differs from a fuse in that a circuit breaker
-melts and must be replaced -is enclosed in a tube of insulating material with metal ferrules at each end -gives no visual indication of having opened the circuit -trips to break the circuit and may be reset
ANS- D 31. Incandescent lamps are classified according to
-shape of bulb and type of service -size and style of base -operating voltage and wattage -all of the above
ANS- D 32. As a general rule, the first troubleshooting action to be taken in checking faulty electric electric control devices is to
-draw a one line diagram of the circuitry -test all fuses and measure the line voltage -take megger readings -insulate the apparatus from ground
ANS- B 33. An electrical device which employs a stationary armature and a rotating electromagnetic field is used aboard ship as a
-magnetic amplifier -ship's service alternator -three-wire DC generator -saturable core reactor
ANS- B 34. The state of charge of a lead acid storage battery is best indicated by the
-testing of the individual cell voltages -ampere hour capacity of the battery -specific gravity of the electrolyte
-total cell voltages
ANS- C 35. The first requirement for logical troubleshooting of any system is the ability to
-collect all available data on a casualty -recognise normal operation -identify the probable cause of a symptom s ymptom -isolate the faulty component
ANS- B 36. The load sharing characteristics of two diesel generators operating in parallel are mostly dependent on their governor
-load limit settings -idle speed settings -speed limit settings -speed droop settings
ANS- D 37. The open circuit voltage of a fully charged lead-acid battary cell is
-1.5 v -1.8 v -2.0 v -2.3 v
ANS- C 38. In an AC generator, direct current from a separate source is passed through the windings of the rotor
-by means of slip rings and brushes -by means of a commutator -by means of rotating bar magnet -to minimize the danger of arc over
ANS- A
39. A delayed-action fuse is most frequently used in which of the listed
circuits? -lighting circuit -motor circuit -electric heater circuit -radar circuit
ANS- B 40.Which of the listed procedures should be carried out to prevent moisture damage to electrical apparatus during extended periods of idleness?
-fill the motor housing with CO2 to inert the space -strap silica gel around the commutator -place heat lamps in the motor housing -cover the equipment with a canvas tarpaulin
ANS- C 41. A fuse of recommended current and voltage ratings that blows often should be replaced replaced only with a fuse of
-the same ratings -higher ratings -higher current and lower voltage rating -lower current and higher voltage rating
ANS- A 42. Which of the listed conditions is an an advatage of a PN diode over a vacuum diode?
-longer life -no warm up time -less delicate -all of the above
ANS- D 43. The freezing point of the electrolyte in a fully charged lead-acid battery will be
-higher than in a discharged battery -lower than in a discharged battery -the same as in a discharged battery -higher than in a discharged battery, but the specific gravity will be less
ANS- B 44. To repair a small electrical motor that has been submerged in saltwater, you should
-wash it with fresh water and apply an external ex ternal source of heat -renew the windings -send it ashore to an approved service facility -rinse all electrical electrical parts with a carbon carbon tetrachloride cleaning solvent and then blow dry the motor with compressed air
ANS- A 45. The basic measuring measuring unit of inductance is the
-coulomb -ohm -farad -henry
ANS- D 46. Which of the listed precautions should be taken when cleaning the internals of a motor with compressed air?
-open the machine on both ends so as to allow the air and dust to escape -be certain that the circuit breaker is opened and tagged on the feeder panel -be cetain that the air is clean and as dry as possible -all of the above
ANS- D 47. The pupose of DC generator brushes is to
-neutralize armature reaction -conduct electric current to an outside circuit -convert DC current to AC current -provide excitation to a DC generator
ANS- B 48. Fuses are rated in
-voltage -amperage -interrupting capacity -all of the above
ANS- D 49. Power transformers are rated in
-kilowatts -ampere-turns -kilowatt-volts -kilovolt-amperes
ANS- D 50. Alternative current circuits develop resistance, inductance and capacitance. The inductance of a coil is expressed in
-ohms -mhos -henrys -farads
ANS- C 51. A lead-acid battery is considered fully charged when the
-electrolyte gasses freely -battery charger ammeter indicates a positive reading -terminal voltage reaches a constant value at a given temperature -specific gravity of all cells reaches the correct value and no longer increases over a period of 1 to 4 hrs
ANS- D 52. The insulation resistance of electric equipment and machinery should be tested for the lowest normal insulation values
-immediately after shutting down the machine -every time the brush rigging is adjusted -immediately after starting up the machine -every 30 days whether the machine is in use or not
ANS- A 53. High vacuum diodes, gas-filled diodes, and germanium semiconductor diodes may all be used as
-potentiometers -rectifiers -power sourses -photocells
ANS- B 54. The apparent power in a purely inductive circuit is also known as
-true power -lead power -induced power -reactive power
ANS- D
55. Which of the following devices will prevent a DC generator from becoming motorized? motorized?
-overcurrent relay -motorization trip -reverse power relay -reverse current relay
ANS- D 56.A grounded switch or cable will be indicated by a meg ohmmeter reading of
-infinity -zero -being unsteady in the high range -being unsteady in the low range
ANS- B 57. Regarding battery charging rooms, ventilation should be provided
-at the lowest point of the room -horizontally near the batteries -at the highest point of the room
-only when charging is in progress
ANS- C 58. The main main difference between an electron tube and a transistor is the
-type of function they can perform -reaction of electron flow through a gas or v acuum in a transistor -reaction of electron flow through a semiconductor when placed in a tube -reaction of electron flow through a semiconductor used to form a transistor
ANS- D 59. A generator has been exposed to water and is being checked for its safe operation. Therefore, it is necessary to
-check for shorted coils with a growler -take moisture readings with a hydrometer -test insulation values with a megger -ground the commutator, or slip rings and run it at half load for 12 hours
ANS- C 60. Before testing insulation with a meg ohmmeter, the windings of large machines should be grounded for about 15 minutes just prior to test, because the
-static charge of the machine may give a false reading -armature will have a greater number of leakage paths -insulation may be damaged -insulation may be covered with moisture
ANS- A 61. In a DC series circuit, all the conductors have the same
-power expended in them -voltage drop across them -resistance to current flow -current passing through them
ANS- D 62. A three-phase induction-type motor experiences an open in one phase. Which of the listed automatic protective devices will prevent the machine from being damaged?
-overspeed trip -thermal overload relay -three-pole safety switch -magnetic blowout coil
ANS- B 63. Most three-phase induction motors used for driving engine room auxiliaries are started by
-resistor starters -across-the-line starters -impedance starters -reactor starters
ANS- B 64. When electrical cables penetrate watertight bulkheads,
-they should be grounded on either side of the bulkhead -they must be bent to a radius of o f six diameters -a watertight stuffing tube capable of accepting packing should be employed -they should be secured by a clamp
ANS- C 65. Across-the-line starters are used with AC motors to provide
-reduced starting current -regulated starting current -high starting torque -controled starting acceleration
ANS- C 66. Most conductive materials such as copper, aluminium, iron, nickel
-increase in resistance with increased temperature -increase in resistance with decreased temperature
-decrease in resistance with increased temperature -decrease in resistance with decreased temperature
ANS- A 67. The electrician reports to you that he has obtained low (but above 1 megohm) megger readings on the windings of a deck winch motor. Upon checking the records of that motor, you find the readings have consistently been at the same level the last six years. You should, therefore, recommend that the
-motor be replaced -windings be dried -windings be cleaned -readings are acceptable
ANS- D 68. Line losses in a distribution circuit are kept to a minimum by
-adding rubber insulation conductors to the circuit -using higher current and lower voltage -increasing the number of thermal relays in the circuit
-using higher voltage and lower current
ANS- D 69. Adding resistance in series with the field winding of a DC shunt motor without a load, will cause the motor speed to
-increase -decrease -remain the same -fluctuate rapidly
ANS- A 70. The function of the compensating windings used in a DC generator is to
-prevent cross-commutation -increase armature coil strength -increase field strength -neutralize armature reaction
ANS- D 71.Capacitors are used on the output of the power supply in today's consoles to
-filter out "ripple" -prevent overloads -act as a permanent load -decrease the average value of the output voltage
ANS- A 72. The purpose of a motor under voltage protection device is to
-prevent high armature current when power is restored -start the motor at a very low voltage -trip the load off the motor in case of fire -protect personnel from low voltage shocks
ANS- A 73. In testing a three-phase delta winding for an open circuit using a meg ohmmeter, you must
-test each phase with all connections intact -measure the voltage across the open connections conn ections while testing -test the windings as parallel groups to avoid short circuiting -open the delta-connections to avoid shunting the phase being tested
ANS- D 74. The direction of rotation of an induction motor motor is
-opposite to the rotating field -the same as the direction of the rotating field -determined by the number of poles -determined by the staggering of the brushes
ANS- B 75. mercury filled thermometers should never be used to determine the temperature of the battery electrolyte because accidental breakage of
the thermometer can cause -severe sparking and explosions
-rapid oxidation of battery plates -contamination of the electrolyte -corrosion on the battery terminals
ANS- A 76. The purpose of a main switchboard circuit breaker's revers-power trip is to
-prevent main circuit overload -protect the circuit breaker blowout coil -prevent alternator motorization -prevent low voltage tripout
ANS- C 77. When charging lead-acid batteries, the charging rate should be reduced as the battery nears its full charge to
-prevent damaging battery plates -allow equalization of cell voltages -reduce lead sulfate deposites -increase lead peroxide formation
ANS- A 78. Regarding an induction motor, the power developed by the rotor automatically adjusts itself to
-power required to drive the load -speed required to drive the load -current flow in the motor stator -torque developed by the rotating field
ANS- A 79. The purpose of a magnetic relay is to
-open a circuit only in the event of overload -remotely open and close contacts -provide overcurrent protection during starting -relay voltages at increased power
ANS- B
80. A semiconductor is a material with a
-conductivity higher then a normal conductor -conductivity higher then a normal insulator -high conductivity at low temperatures -low conductivity at high temperatures
ANS- B
SECTION 4 1. For a given line voltage, four heating coils will produce maximum heat when connected in …………….
ANS- Parallel
2. The unit of absolute permittivity of a medium is- ………….
ANS- Farad/ metre
3. The unit of electric intensity is- ………
ANS- Volt/ metre
4. In practice , earth is chosen as a place of zero electric potential because it- …..
ANS- Has almost constant potential
5. Current carried by each of the two long parallel conductors is doubled. If their separation is also doubled , force between them is- ………
ANS- Increase two fold
6. The direction of induced EMF can be found with the help of - …………….
ANS- Lenz’s Law
7. Permanent magnets are generally made of- …….
ANS- Alnico alloys
8. The rate of rise of current through an inductive coil is maximum- ………
ANS- At the start of the current flow 9. A material with very less flow of electrons is called
ANS- insulator
……….
11. VGS and Id approximately zero....this is called ____ _________ voltage
ANS-
cut off
11. The winding resistance of a coil can be increased by _______ the number of turns or using a ______ wire. wire.
A. increasing, thicker B. decreasing, thicker C. increasing, thinner D. decreasing, thinner
ANS- C 12. The most common source of excitation for synchronous motors is a/an _____________. (A) low voltage battery (B) motor attenuator set (C) DC exciter generator (D) AC supply
ANS- C
12. A sine wave consists of no of c ycles
…….
ANS- 2 cycles
14. On an engine throttle control co ntrol system, the aux control circuits are provided with devices to prevent excessive over travel of the pilot valve by the synchronous motor these devices are called. A. overlap sensor B. limit switch C. over travel relay D. proximity switch
ANS- B
15. The speed of the squirrel cage induction motor is determined by by A. Dia of stator B. No of stator poles C. Rotor winding resistance D. Bar resistance of conducting rotor
ANS- B
16. The method used to produce electron emission in most vacuum tubes is known as A. Photo electric emission B. Secondary electric emission C. Cold cathodic electric emission D. Thermionic emission
ANS- D
17. A reverse current relay prevents dc generator motorization automatically by option A. Redirecting up prime mover, B. Securing the exciter generator, C. Tripping the circuit breaker.
ANS- C
18. The output voltage of a there phase alternator is regulated by
…………..
ANS-dc voltage to the field.
19. Di electric constant of 3.6 A. Water B. Paper C. Electrolyte D. Air
ANS- B
20. RMS value of a sine wave current is expressed as A. Average value, B. Max value C. Effective value D. Instantaneous value
ANS- C
21. Which of the following statements comparing transistors and vacuum t ubes is correct?
A. Both transistors and vacuum tubes have a cathode that must be heated to give off electrons. B. A vacuum tube must have a heated cathode, where transistors do not. C. Neither transistors nor vacuum tubes require heat for electrons to flow. D. The anode of both transistors and vacuum tubes must be heated to give off electrons.
ANS- B
NEW SECTION - 1
1. Electric and electro-hydraulic steering gear motors are required by Coast Guard Regulations (46 CFR) to be _________.
A. protected by a circuit breaker set at 125% and a thermal overload device B. provided with a running motor overcurrent protection device C. served by a single two conductor cable D. served by two feeder circuits
ANS- B
