Assessment Test

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1. What is the name of the semiconductor that decreases in resistance with an increase in temperature?


2. Which of the following statements correctly applies to bipolar junction transistors?


3. In what applications are germanium semiconductor diodes commonly used?


4. In comparing a semiconductor diode to a vacuum tube diode, what statement is true?


5. Which of the following statements represents an application of a silicon controlled rectifier?


6. Silicon diodes which are designed for a specific reverse breakdown voltage, and are most often used as electronic power supply voltage regulators, are specifically what type of diode?


7. A signal derived from an amplifier output and returned to the amplifier input is called what type of signal?


8. A common-emitter circuit has an input voltage of 0.1 volt, an output voltage of 2.0 volts, an input current of 0.5 milliamps, and an output current of 10 milliamps. What is the power gain?


9. An voltage amplifier has a calculated voltage gain of 5. Which statement is true concerning input and output voltages?


10. How are operational amplifiers, used primarily in analog circuits, characterized?


11. Which of the following is a disadvantage of electric drive propulsion systems?


12. Which statement is TRUE concerning electric propulsion drives?


13. An electric propulsion drive system in which the propulsion generator supplies power to both the propulsion motor and ship service loads is referred to as what type of system?


14. What is one major advantage of a diesel electric propulsion plant?


15. Ships requiring rapid maneuvering response with a high degree of main propeller shaft control are most often what type of drive system?


16. Which of the listed temperature measuring devices installed on a large turbo-electric alternating current propulsion generator would be the most reliable for monitoring generator temperatures to avoid premature winding insulation failure?


17. What is the operating function of a cycloconverter (CCV) as a static power converter used in electric propulsion motor drives?


18. The propulsion motor most often utilized in an ac drive system operating in the moderate to high power range is of what type?


19. How is the main shaft rotation on an AC diesel-electric propulsion vessel normally reversed?


20. By what common means is the speed of the AC propulsion motor on a diesel-electric propulsion ship controlled?


21. While standing an "at sea watch" onboard an AC diesel-electric drive ship with a synchronous propulsion motor, you notice that the kwatt load is at roughly 75% of capacity with a leading power factor less than 1. Ideally what would be the character of the power factor associated with the main power distribution including all motors?


22. What type of motor is generally used in DC propulsion drive systems?


23. How is the main propeller shaft rotation of a rectified DC diesel-electric drive normally reversed?


24. In a diesel electric plant, raising the generator's field excitation current will have what effect on the DC propulsion motor speed?


25. What equipment for modern SCR rectified DC propulsion drive systems is usually included in the package?


26. What statement is TRUE concerning the Azipod propulsion system?


27. Which of the following statement is TRUE concerning Azipod propulsion systems?


28. In an azipod propulsion system, how is three phase, frequency and voltage controlled power delivered to the synchronous propulsion motor stator windings?


29. In an azipod propulsion system, how is direct current delivered to the synchronous propulsion motor rotor for synchronous operation?


30. In an azipod propulsion system, how is the azipod unit itself rotated for the purposes of directing the thrust in accordance with steering commands from the bridge?


31. For the purposes of high voltage marine practice, what is the threshold voltage where all voltages below this value are considered low voltage?


32. What is a disadvantage to the use of high voltage systems onboard ship?


33. What is the most common and reliable type of circuit breaker used for high voltage practice aboard ship?


34. Some shipboard high voltage systems have the neutral point of the generators bonded to the ship's hull with a neutral grounding resistor. What is the purpose of this resistor?


35. Suppose it is desired to determine the integrity of the insulation of a 4160 VAC motor. What type of insulation resistance tester (megger) would be suitable?


36. Before work may safely commence on a high voltage system, what must first be done after disconnection and isolation?


37. In order for a live-line tester to be used to test and prove dead a high voltage circuit, what must be done to verify the ability of the tester to detect a voltage?


38. In addition to high voltage circuit grounding with ground-connecting switching devices, for additional operator safety and confidence, portable grounding straps may be used. What is the proper procedure for connecting these portable grounding straps?


39. When completing repairs on a high voltage circuit where portable grounding straps were used for increased operator safety and confidence, what is the proper procedure for disconnecting these grounding straps?


40. For a motor rated at 3.3 kV, what would be a minimum accepted insulation resistance to hull ground as tested by an appropriate megger (insulation tester)?


41. To facilitate communication between the wheelhouse and the steering gear room in a steering emergency where no external source of power is required, what means of two-way communication would be provided?


42. Which station's emergency loudspeaker must allow for two-way communication?


43. Assuming the vessel has an engine control room, where is an engineers' assistance- needed alarm required to produce an audible signal?


44. In a typical fire detection control unit, what would be indicated by an illuminated blue light?


45. Which of the following fixed temperature heat-actuated fire detectors can be reused after it has detected a fire?


46. Which of the following fixed temperature heat-actuated fire detectors is the most prone to false alarms?


47. What shipboard system uses the synchronous transmission system?


48. The shaft revolution indicator system for a fixed pitch propeller has which of the following display capabilities?


49. A pyrometer indicating system such as that used for measuring diesel engine exhaust system temperatures uses what technology?


50. A bearing temperature monitoring system such as that used for measuring selected propulsion plant bearings uses what technology?


51. A salinity indicator system such as that used to measure the salt content of potable water systems and boiler feed and condensate systems uses what technology?


52. On vessels with AC distribution systems, which of the following statements represents the most difficult problem involved in obtaining a DC potential suitable for use by computer components?


53. What statement is true concerning read only memory (ROM)?


54. What statement is true concerning random access memory (RAM)?


55. Which of the following devices represents primary storage, where the processor is able to directly read instructions and data and directly return results of its computation in fetch/execute cycles?


56. Which of the following data communication cable types offers the greatest immunity to electromagnetic "noise"?


57. What type of local area network physical topology features point-to-point interconnection between all communicating devices and is the least vulnerable to a break in communication?


58. Modern ships use multiple computers arranged in a client/server network to perform various shipboard functions. What type of computer network would most likely be used aboard ship?


59. What Ethernet cabling technology supports the greatest data transfer speeds?


60. If an 8-bit digital to analog converter (DAC) produces an analog output voltage with a range of 10 volts (0-9 volts), what is the smallest incremental step in voltage that can be generated at the output?


61. If a computer display is flickering, how may this be remedied?


62. In an impressed current cathodic hull protection system, what statement is true concerning the composition and arrangement of the anodes?


63. While monitoring an impressed current cathodic hull protection system, which of the following measurements should remain constant in a properly operating electronically regulated system?


64. In monitoring an impressed current cathodic hull protection system, it is important to insure that the propeller screw receive the same cathodic protection as the hull. What should be checked for?


65. In the event of a power failure during cargo loading operations, the movement of an electric powered cargo winch will be stopped by what means?


66. When the control handle is in the 'off' position, what is the status of the solenoid actuated brake of an electric winch?


67. When power is restored after a complete power failure, how will the steering gear pump motor which was on-line respond?


68. The electrical energy necessary to power a sound-powered telephone's small vibrating bell is obtained from what power source?


69. If overloading an electric motor becomes necessary in an emergency situation, what should be done to prevent damage to the motor while allowing sustained operation?


70. What should be included in the routine periodic maintenance checks for electrical motors?


71. When testing insulation resistance of electric equipment and machinery, ideally when should the insulation resistance be tested for the lowest normal insulation values?


72. What would be the indication of a grounded switch or cable as measured by a megohmmeter?


73. Before any work on electrical or electronic equipment is performed, which of the following precautions should be carried out?


74. What should you be aware of when checking the specific gravity of the battery electrolyte with a hydrometer?


75. For accuracy purposes, which of the following devices should be used to measure the temperature of a battery electrolyte?


76. Which of the substances listed should be applied to battery terminals to help prevent corrosion?


77. 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?


78. What is the best method of determining the state of charge of a lead acid storage battery?


79. Which of the following activities occurs during the charging process of a lead-acid storage battery?


80. Why must caution be exercised during the charging of lead-acid storage batteries?


81. What statement is true concerning the actual mixing process and the container used when mixing electrolyte for a lead-acid storage battery?


82. Which of the following statements concerning Nickel-Cadmium batteries is true?


83. You are reconnecting a three-phase induction motor to the supply line. To prevent possible damage to the load, due to the wrong direction of rotation, what should be done?


84. Which of the conditions listed will indicate the need to clean the insulation on the windings of an electric motor?


85. What is a useful instrument for checking 3 phase A.C. motor performance by measuring possible unbalanced currents?


86. Large machines undergoing a resistance insulation testing using a megohmmeter should be discharged to remove any accumulated electrostatic/capacitive charge stored. When should this discharge be performed?


87. Why are large cable sizes often formed as individual conductors comprised of several smaller strands?


88. When electrical cables penetrate watertight bulkheads, what must be provided for?


89. Why is copper often used as an electrical conductor?


90. How are the line losses in a distribution circuit kept to a minimum?


91. Which of the following represents a characteristic of an ungrounded electrical distribution system?


92. The timer element of a reverse power relay cannot be energized unless what condition is met?


93. How is a wattmeter electrically connected in a circuit?


94. What is the name of the part of the shipboard electrical system used to control the distribution of power to the branch circuits?


95. Upon failure of the normal power supply, how is the emergency generator placed on the line to feed power to the emergency bus?


96. Which of the following statements concerning analog and digital devices is correct?


97. The multiplier prefix 'giga' (G) such as used in "gigabytes" represents what multiplication factor?


98. Which of the substances listed can be used to shield sensitive equipment from static magnetic fields?


99. When placed in a magnetic field, which of the materials listed will maintain the highest permeability?


100. A silicon controlled rectifier (SCR) is a solid state device used for what functional purpose?


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