Electrohydraulic Load-Sensing Governors and Degaussing

Card Set Information

Electrohydraulic Load-Sensing Governors and Degaussing
2013-02-09 20:54:38
EM study guide

Chapters 9 and 10 EM rating manual
Show Answers:

  1. What is the advantage of using electrohydraulic governors instead of mechanical governors?
    Electrohydraulic governors provide closer frequency regulation
  2. Which of the following is a disadvantage of obtaining the speed signal of a governor by sensing the output frequency of the generator?
    A short circuit on the generator could result in a loss of signal
  3. What means is used to obtain stability in the prime mover?
    Electrical feedback circuits
  4. What does the speed droop do for the operation of a generator?
    It allows you to parallel generators that have dissimilar governors
  5. Which of the following means should be used to give the governor a signal that corresponds to the speed of the equipment under control?
    A permanent magnet generator or alternator mounted on the shaft of the equipment
  6. What means is used to connect the load-measuring circuits of governors on all generators operating in parallel?
    A bus tie cable
  7. What is the purpose of the load signal box in EG-R governors?
    To detect changes in the load before they appear as speed changes
  8. What device is used to couple the EG-R hydraulic actuator to the remote servo piston?
    High-pressure lines
  9. What type of governor system offers the highest work capacity?
  10. If a negative dc voltage is sent to the actuator from the electronic control box, what will happen to the pilot valve plunger?
    It will travel in an upward direction 
  11. If the power piston is forced down, the fuel flow to the prime mover will react in what way?
    It will increase
  12. Control oil pressure is approximately (a) what amount of (b) what oil pressure?
  13. Prevents overtravel of the throttle by reacting to a temporary negative feedback signal in the form of a pressure differential across it during changes in position of the power piston
    Compensation land.
  14. Acts to produce the temporary negative feedback (in the form of a pressure differential) applied to the compensation land of the pilot valve plunger during speed changes
    Buffer system
  15. Used to control the rate at which the pilot valve plunger returns to the centered position after a change in load condition on the prime mover
    Needle valve
  16. Reacts to the position of the control land to increase or decrease the speed of the prime mover through a linkage to the fuel or steam valve
    Power piston
  17. By what means does the EG-R actuator control the position of the prime mover fuel or steam supply?
    By controlling the flow of oil to and from the upper side of the power piston in the remote servo
  18. With the pilot valve of the EG-R actuator centered, in what direction, if any, is oil directed by the power piston?
    None; no oil flows
  19. An increase in prime mover speed will cause the EG-R control box to send a signal to complete what action?
    Raise the pilot valve plunger
  20. The pilot valve plunger of the EG-R actuator is moved by the pressure on top of the compensation land. What component controls the rate at which the plunger moves?
    The needle valve setting
  21. Which of the following is an application of a hydraulic amplifier?
    Operating a power control mechanism when a relatively large force is required
  22. When used, the three-way valve of the EG-R hydraulic actuator must be turned to drain after starting for what reason?
    Oil would be trapped under the pilot valve plunger, making the amplifier inoperative
  23. Which of the following is NOT a use of the EG-M control box?
  24. It is desirable to detect load changes and respond to them before they appear as turbine speed changes for what reason?
    To minimize speed change transients
  25. What is the primary source of most problems in the hydraulic actuator or valve operator?
    Dirty oil
  26. A ship’s magnetic field moves with the ship through the water. Because of this magnetic field, the ship can trigger magnetic-sensitive ordnance. Degaussing systems are used aboard ship for which of the following reasons?
    To help reduce the ship’s distortion of the earth’s magnetic field
  27. The lines of magnetic force at the earth’s surface don’t run in straight lines. They appear more like isobar lines on a weather map. The lines of force interact with ferrous materials in what way?
    They distort the background field into areas of increased or decreased magnetic strength
  28. On earth, where is the south magnetic pole located?
    In the northern hemisphere
  29. The earth’s magnetic field is made up of what components?
    H and Z
  30. What instrument is used to determine the angle of the horizontal field?
    A dip needle 
  31. At the equator, what is the vertical intensity of the earth’s magnetic field?
  32. The magnitude of a ship’s permanent magnetism depends on which of the following conditions?
    1. The earth’s magnetic field where the ship was built 2. The material from which the ship is constructed3. The orientation of the ship at the time the ship was built with respect to the earth’s magnetic field 4. All of the above
  33. Navy ships are depermed for which of the following reasons?
    1. To increase the number of the ship’s effective degaussing coils 2. To decrease the permanent magnetization of the ship 3. To decrease the induced magnetization of the ship 4. All of the above
  34. The earth’s magnetic field lines of force enter the surface at what location?
    The south magnetic pole
  35. At what location on the earth’s surface do the magnetic lines of force point away with the strongest flux?
  36. The horizontal component of the earth’s magnetic field is maximum at which of the following locations?
    The magnetic equator 
  37. A ship’s induced magnetism depends on which of the following components?
    The strength of the earth’s magnetic field 2. The heading of the ship with respect to the inducing earth’s magnetic field
  38. What two field components make up the horizontal field of a ship’s induced magnetism?
    The longitudinal and athwartship 
  39. The magnitude of the vertical field component of a ship’s induced magnetization depends on what factor?
    The magnetic latitude
  40. The equipment that measures the magnetic field of a ship at a degaussing range has which of the following physical locations?
    At or near the bottom of the channel
  41. A ship is check ranged for which of the following reasons?
    To ensure that the current settings are adequate

    (i think)
  42. At what specified interval must minesweepers be checked at a degaussing range?
  43. What is the minimum number of coils in a degaussing system?
  44. Degaussing coils are energized from what type of power sources?
    Direct current
  45. The magnetic fields produced by the permanent and induced vertical components of a ship’s magnetization are counteracted by which of the following degaussing coils?
    M coil
  46. The ship’s vertical induced magnetization varies with which of the following factors?
    1. The ship’s latitude 2. The ship’s pitch 3. The ship’s roll 4. All of the above
  47. The forward one-fourth to one-third of a ship is encircled by which of the following coils?
  48. The strength of the FI-QI and FP-QP coils depends on which of the following factors?
    The ship’s latitude and heading
  49. The FI-QI degaussing coils counteract which of the following fields?
    Longitudinal Induced
  50. The L coil is installed aboard what type of ship?
  51. A degaussing coil for correcting athwartships permanent and athwartships induced magnetization has what designation?
  52. Magnetic fields produced by the permanent and induced longitudinal components of a ships magnetization are counteracted by which of the following coils?
    1. F 2. L 3. Q 4. Each of the above
  53. Which of the following conditions can change a ship’s attitude?
    1. Roll 2. Trim 3. Heading 4. Each of the above
  54. What equipment is used to automatically control the current of degaussing systems?
    A gyrocompass and magnetometer control
  55. A magnetometer that controls the induced field currents receives a signal from what total number of axes?
  56. The AUTODEG equipment must be secured if the automatic controls become inoperative.
  57. Magnetometer-controlled AUTODEG equipment has what total number of modes of operation?
  58. The degaussing system coil turns, current magnitude, and polarities for a ship are established during calibration. Calibration is accomplished at what location?
    degaussing range
  59. Degaussing coil currents should be monitored and compared to which of the following values?
    Those recorded in the degaussing folder
  60. When the EMS degaussing system is in the manual mode, the M-coil switch is set to what polarity?
  61. When the ship’s heading changes and the geographical location does not, the magnitude and polarity of what components will vary?
    • L, A, and FI-QI 
    • (i think)
  62. In the SSM degaussing system, which of the following components is/are installed to warn personnel of faulty operations?
    1. Ground detectors 2. Temperature alarm 3. Blown fuse indicators 4. Each of the above
  63. What method is used to mark the insulating sleeving of degaussing conductors?
  64. In the degaussing system, adjustments for ampere-turn ratios are made in what component(s)?
    The connection boxes 
  65. What is the required length for all conductors inside a connection box?
    1 1/2 times the length to the farthest terminal
  66. The degaussing folder is an official ship’s log.
  67. The degaussing folder is prepared by what person?
    The degaussing range personnel
  68. At what point is the degaussing folder prepared?
    During initial calibration
  69. You should NOT use which of the following equipment to remove dust and dirt from automatic degaussing control equipment?
    LP air
  70. What is the fastest and easiest way for you to check connection boxes or through boxes for moisture?
    remove drain plug