Assessment Test

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1. In addition to improper brush pressure or seating, what can result in excessive sparking at the brushes of a DC propulsion motor?


2. While standing an "at sea watch" onboard a modern rectified DC diesel-electric drive ship you notice the transformer core temperature slowly rising. What should be your FIRST action?


3. Which of the following conditions will occur if the brake solenoid coil burns out on a cargo winch with an electrical brake?


4. An open primary coil in a simple potential transformer will be indicated by which of the listed conditions?


5. What is true concerning the installation of batteries used for diesel engine starting?


6. Why should battery rooms we well ventilated during the charging of storage batteries?


7. Which of the following procedures represents the best method to prevent the freezing of batteries continuously exposed to low temperatures?


8. Which of the following statements describes the effects of ambient temperature on local action within lead-acid storage batteries?


9. What is the nominal open-circuit cell voltage of one lead-acid storage battery cell?


10. To keep emergency lead-acid batteries in a full state of charge for emergency use, what is normally done?


11. Assuming that the electrolyte has had sufficient time to be uniformly diffused throughout the cell, if the open-circuit cell voltage as measured by a digital multimeter is 2.12, what would be the approximate specific gravity?


12. The nominal voltage of one cell of a wet cell nickel-cadmium battery is approximately how many volts?


13. Why are nickel-cadmium batteries superior to lead-acid batteries for standby service?


14. AC circuits can possess characteristics of resistance, inductance, and capacitance. In terms of units of measure, how is the capacitive reactance of the circuit expressed?


15. The root mean square (RMS) value of a sine-wave current may also be expressed as what value?


16. For the purpose of calculating apparent power, which of the following procedures should be used to determine the total load current of a three-phase, delta wound, AC generator?


17. If the voltage and the current developed in an AC circuit reach their peak values at the same time (with a phase angle difference of zero), what is the power factor considered to be?


18. An accidental path of low resistance bypassing the intended path and allowing passage of an abnormally high amount of current is known as what?


19. In the flow of one cycle of single phase alternating current past any given point in a circuit, how many times will the current peak to a maximum?


20. What is the opposition to the establishment of magnetic lines of force in a magnetic circuit called?


21. In terms of load type, in what type of alternating current circuit will the voltage always lead the current?


22. How may the unit "hertz" be best described?


23. What will happen to an electrical coil when the direct current flowing through the coil is increasing?


24. In a series circuit what is the total applied voltage equal to?


25. In a series circuit, which value will remain unchanged at all places in the circuit?


26. Four lamps are connected in series in a single circuit. If one of the lamp burns out, what will happen to the other lamps? Four lamps are connected in series in a single circuit. If one of the lamp burns out, what will happen to the other lamps?


27. Which of the following statements concerning a circuit with parallel connected resistors is correct? Which of the following statements concerning a circuit with parallel connected resistors is correct? Which of the following statements concerning a circuit with parallel connected resistors is correct? Which of the following statements concerning a circuit with parallel connected resistors is correct? Which of the following statements concerning a circuit with parallel connected resistors is correct?


28. Which of the following statements is true concerning circuits with parallel connected resistances?


29. What statement is true concerning the total resistance of a parallel circuit?


30. Four lamps are connected in parallel in a single circuit. If one of the lamp burns out, what will happen to the other lamps?


31. Which statement is true concerning the total power consumed in a parallel circuit?


32. Which of the electrical properties listed will always be the same across each component in a parallel circuit?


33. What will happen to the total circuit resistance when additional parallel circuits are added to a circuit?


34. In a simple DC circuit, the resistance is held constant while the applied voltage is halved. What will be the effect on the current flow as compared to the original current?


35. An electrical component is connected across a 120 volt 60 hertz AC supply. What is the current drawn by the component if the impedance is 200 ohms?


36. In a 60 Hz AC system, what is the duration in seconds for one complete cycle?


37. An AC generator produces 60 Hz at 1800 RPM. If the generator speed is increased to 1830 RPM, what will happen to the frequency in Hz?


38. How is the power dissipated as heat in a direct current circuit calculated?


39. A 125 volt DC motor is rated at 10 kW. What is the current rating of the motor?


40. An AC circuit has a capacitive reactance of 30 ohms in addition to an inductive reactance of 40 ohms connected in series. What is the total reactance of the circuit?


41. Two 100 watt light bulbs rated at 100 volts are connected in parallel across a 100 volt power supply. What will be the total power consumed by the two bulbs?


42. If a circuit has resistances of 5, 10, and 20 ohms connected in parallel, what is the combined total resistance of the circuit?


43. A simple, untapped, single-phase 480/120 VAC step-down control transformer is rated at 600VA at 60 Hz. Neglecting power factor, what is the rated secondary load current?


44. What would be the synchronous speed of an eight-pole three-phase squirrel-cage induction motor operating at 60 Hz?


45. What would be the synchronous speed of a 24-pole three-phase synchronous motor operating at 20 Hz?


46. What would be the actual rotor speed for a 4-pole three-phase squirrel-cage induction motor operating at 60 Hz if the rotor slip is 3%?


47. If a 12-pole three-phase synchronous alternator is operating at 590 rpm, what will be its output frequency?


48. A six-pole three-phase squirrel-cage induction motor operating at 60 Hz is running at 1155 rpm. What is the percentage slip in this case?


49. What is the shape of the schematic symbol for an operational amplifier used in an analog circuit?


50. What is the instrument called a galvanometer used to measure?


51. What is an ohmmeter used to measure?


52. What practice could potentially damage a multimeter?


53. In what situation would an electrical phase sequence indicator be useful?


54. An internal resistance is placed in series with the meter movement of which of the following instruments?


55. When a resistor is used as a shunt and is connected in parallel with a meter movement coil, what capability does this provide?


56. Periodic testing using a special camera may be performed to detect potentially dangerous loose or corroded bus bar and controller connections. What is the name of this testing technology?


57. What is an ammeter used to measure?


58. Why are external shunts sometimes used with ammeters?


59. How should the shunt used in an ammeter be connected?


60. The clamp-on AC ammeter consists essentially of a split-core and a rectifier-type instrument connected to the secondary winding of a particular type of transformer. Which type is used?


61. To properly use a clamp-on-type ammeter to check current flow, what must be done FIRST?


62. Which of the listed statements is correct when using an digital multimeter set up as an ohmmeter?


63. When testing a capacitor with an digital multimeter set up as an ohmmeter, what would be the indication on the display when testing an initially discharged capacitor in good condition?


64. If a digital multimeter set up to measure AC volts reads slightly above 'zero' when its leads are disconnected, what is this a result of?


65. In testing a hand cranked megger prior to use, what statement is true?


66. When a megohmmeter is being used to test insulation resistance, current leakage along the surface of the insulation is indicated by a very specific megohmmeter pointer movement. What would be the characteristic of the pointer movement under these conditions?


67. When a megohmmeter is used to test insulation, what condition causes the gradual rise of the pointer reading as a result of continued cranking?


68. In which of the situations listed will a megohmmeter give the most accurate readings?


69. What condition associated with a lead-acid battery cell can cause the plates to partially short-out and cause the cell to fail to hold a charge.


70. When troubleshooting a lead-acid storage battery, what is the best method for detecting a weak or dead cell?


71. As the electrolyte level in the cells of a lead-acid battery evaporates over time, what will tend to happen to the specific gravity of the electrolyte in the cells as the level drops due to evaporation?


72. What could prevent a lead-acid battery from accepting a full charge?


73. To determine the state of charge of a nickel-cadmium wet-cell storage battery during charging and discharging, what is the most reliable method?


74. The leads from a ohmmeter are attached to the leads of the opposite ends of an AC motor stator field coil. If a reading of infinity is obtained, what does this indicate?


75. A split-phase induction squirrel-cage motor will not start and come up to speed, even though the rated voltage, rated frequency, and rated load are applied. Which of the following troubles would be suspected?


76. Grounds occurring in electrical machinery as a result of insulation failure may result from deterioration over time and excessive heat. What could be another contributing cause?


77. A lightly loaded three-phase squirrel-cage induction motor, while running, begins to vibrate excessively but continues to run. After shutting down the motor, the motor will not restart, but makes growling noises, overheats, and smokes. What caused this?


78. What would excessive sparking at the brushes of a running DC motor be an indication of?


79. If a D.C. motor hums, but does not run when energized, which of the listed conditions could exist?


80. Besides checking for grounds, for what other purpose can a megohmmeter be used on a DC motor?


81. What is the most effective method of locating a loose commutator bar in a D.C. motor?


82. How may temporary repairs to an open DC propulsion armature coil be made, allowing continued operation until permanent repairs can be made?


83. When using a megohmmeter to determine which shunt field coil is grounded in a DC machine, what must you do?


84. What can be the cause of excessive heat or burning contacts in an operating motor controller?


85. If a shipboard AC generator experiences a failure to produce a voltage, what may be the cause?


86. How can the loss of residual magnetism in an alternator or generator be corrected?


87. What may cause brush sparking in a DC generator during commutation?


88. Hysteresis is one cause of electrical power loss associated with electricity generation equipment. What phenomenon results in hysteresis?


89. What can cause uneven wear of the commutator surface on a direct current generator?


90. If a self-excited DC generator running at rated speed fails to deliver an output voltage, which of the following conditions may be a cause of this difficulty?


91. The ground indicating light on the main electrical switchboard is indicating a ground. What is the best procedure for locating the grounded circuit?


92. In an ungrounded distribution system, as compared to a normal indication, what is the indication on a switchboard of a current carrying conductor making an accidental electrical contact with a wiring metal conduit?


93. What effect will increasing the power source frequency have in a capacitive circuit?


94. Which of the procedures or conditions listed could result in damaging a transistor beyond repair?


95. When troubleshooting most electronic circuits, what voltmeter characteristic can minimize the 'loading effect'?


96. Normally, what is the FIRST step in troubleshooting a transistor mounted on a circuit card?


97. If both the 'high level' and 'low level' alarms come on for the same address of a centralized control console, what is the most likely failure?


98. A full-wave rectifier has one diode burned out in an open condition, what will be the output characteristic of the device?


99. When troubleshooting an electronic circuit, an unreliable high resistance "cold" solder joint can be located with the aid of an ohmmeter. Once the problem has been located, what should be done?


100. On a vessel with turbo-electric drive, which of the following conditions would indicate that the propulsion motor had dropped out of synchronization with the propulsion generator?


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