Neets Module 15 Assignment 1

Card Set Information

Neets Module 15 Assignment 1
2012-08-09 16:35:00

Show Answers:

  1. What is the name given to a variety of rotary electromechanical, position sensing devices?
    The synchro.
  2. What is the primary purpose of a synchro system?
    Precise and rapid transmission of data between equipment and stations.
  3. Name the two general classifications of synchro systems.
    • Torque
    • Control.
  4. What is the difference between a torque synchro and a control synchro?
    A torque synchro is used for light loads and a control synchro is used in systems desired to move heavy loads.
  5. Name two synchros that provide a mechanical output.
    • The torque receiver (TR)
    • The torque differential receiver (TDR).
  6. What does the code 26V-11TX4D mean on a synchro nameplate?
    It is the third modification of a 26-volt 400-hertz (torque) synchro transmitter whose body diameter is between 1.01 and 1.10 inches.
  7. Which of the two synchro designation codes is indicated by 5DG on a synchro nameplate?
    The Navy prestandard designation code.
  8. On the synchro schematic symbol, what indicates the angular displacement of the rotor?
    The position of the arrow.
  9. What are the two major components of a synchro?
    The rotor and the stator.
  10. Which of the two main types of rotors can have either a single winding or three Y-connected windings?
    The drum or wound rotor.
  11. How does the stator receive its voltage?
    By the magnetic coupling from the rotor.
  12. Where are the external connections made on standard synchros?
    At the terminal board.
  13. What major factors determine the load capacity of a torque-synchro transmitter?
    • The number and type of synchro receivers
    • The mechanical loads on these receivers
    • The operating temperatures of both the transmitter and receivers.
  14. Define the term "torque."
    A measure of how much load a machine can turn.
  15. What unit of measurement refers to the torque of a synchro transmitter?
  16. What type of equipment normally uses 26-volt 400-hertz synchros?
  17. When will a synchro generate more heat than it is designed to handle?
    When it is overloaded.
  18. How do synchros differ from conventional transformers?
    Synchros have one primary winding that can be turned through 360� and three secondary windings spaced 120� apart.
  19. Describe the zero-position of a synchro transmitter.
    The transmitter is in its zero-position when the rotor is aligned with the S2 stator winding.
  20. When is the maximum voltage induced into a stator coil?
    When the rotor coil is aligned with the stator coil.
  21. What three factors determine the amplitude of the voltage induced into a stator winding?
    • The amplitude of the primary voltage
    • The turns ratio
    • The angular displacement between the rotor and the stator winding.
  22. What is the physical difference between a synchro transmitter and a synchro receiver?
    A synchro receiver uses some form of damping to retard excessive oscillations or spinning.
  23. What method is used to prevent oscillations in large synchro units?
    Mechanical damping.
  24. What two components make up a simple synchro transmission system?
    • A synchro transmitter
    • A synchro receiver.
  25. What leads in a simple synchro system are connected to the ac power line?
    The rotor leads.
  26. What is the relationship between the transmitter and receiver stator voltages when their rotors are in correspondence?
    The voltages are equal and oppose each other.
  27. What is the name given to the angle through which a transmitters rotor is mechanically rotated?
  28. What two receiver leads are reversed to reverse the rotor's direction of rotation?
    1 and S3.
  29. What is the most likely problem if the transmitter shaft reads 0� when the receiver shaft indicates 180�?
    The rotor leads on either the transmitter or the receiver are reversed.
  30. What is the purpose of using differential synchros instead of regular synchros?
    Differential synchros can handle more signals than regular synchros and also perform addition and subtraction functions.
  31. What are the two types of differential synchros?
    • The TDX
    • The TDR.
  32. Other than their physical differences, what is the major difference between a TDX and a TDR?
    Their application: a TDX has one electrical and one mechanical input with an electrical output.
  33. What determines whether a differential synchro adds or subtracts?
    The way the differential synchro is connected in a system is the deciding factor on whether the unit adds or subtracts its inputs.
  34. In a TDX system when does the TR rotor follow the TX rotor exactly?
    When the TDX rotor is on 0�.
  35. What is the angular position of a TX rotor when it is pointing toward the S1 winding? (Hint. Remember synchros are labeled counter clockwise from 0�.)
  36. In a TDX system with standard synchro connections, the TX rotor is at 120� and the TDX rotor is at 40�. What position will the TR indicate?
  37. What connections in a TDX system are reversed to set up the system for addition?
    The S1 and S3 leads are reversed between the TX and the TDX, and the R1 and R3 leads are reversed between the TDX rotor and the TR.
  38. What connections in a TDR system are reversed to set up the system for addition?
    The R1 and R3 leads between the TDR rotor and the TX to which it is connected.
  39. In a TDR system connected for addition in what direction will the TDR rotor field turn when the TX rotor to which it is connected turns counterclockwise?
  40. What type of synchro is used in systems requiring large amounts of power and a high degree of accuracy?
    A control synchro.
  41. What are the three types of control synchros?
    • CX
    • CT
    • CDX.
  42. How do the CX and CDX differ from the TX and TDX?
    The CX and CDX have higher impedance windings.
  43. What three things prevent a CT rotor from turning when voltages are applied to its stator windings?
    The rotor is specially wound, it is never connected to an ac supply, and its output is always applied to a high-impedance load.
  44. When a CT is on electrical zero, what is the relationship between its rotor and the S2 winding?
    They are perpendicular to each other.
  45. What is the amplitude and voltage induced into the rotor when the CX is turned 90� while the CT remains on electrical zero?
    The voltage is maximum and in phase with the ac excitation voltage to the CX.
  46. What is the name given to the electrical output of a CT?
    Error signal.
  47. In a control synchro system, when is the output of the CT reduced to zero?
    When the CX and CT rotors are in correspondence.
  48. What is the purpose of the synchro capacitor?
    To improve overall synchro system accuracy by reducing stator currents.
  49. What type of synchros usually require the use of synchro capacitors?
    • TDXs
    • CDXs
    • Cts.
  50. What type of current is eliminated by synchro capacitors?
    Magnetizing current.
  51. How are synchro capacitors connected in a circuit?
    They are delta-connected across the stator windings.
  52. Why are synchro capacitors placed physically close to differentials transmitters and CTs?
    To keep the connections as short as possible in order to maintain system.
  53. What is the name given to the synchro system that transmits data at two different speeds?
    A dual or double-speed synchro system.
  54. What is the main reason for using a multispeed synchro system instead of a single-speed synchro system?
    Greater accuracy without the loss of self-synchronous operation.
  55. In a dual-speed synchro system what determines the two specific speeds at which the data will be transmitted?
    The gear ratio between the two transmitters.
  56. What type of synchro system is used to transmit very large quantities?
    A tri-speed synchro system.
  57. What is the disadvantage of using a double receiver instead of two individual receivers?
    If one of the receivers goes bad the entire unit must be replaced.
  58. What is the purpose of "stickoff voltage"?
    It is used in synchro systems to prevent false synchronizations.
  59. What is the reference point for alignment of all synchro units?
    Electrical zero.
  60. What is the most accurate method of zeroing a synchro?
    The voltmeter method.
  61. What is the purpose of the coarse setting of a synchro?
    It ensures the synchro is on 0�, not 180�.
  62. When is a synchro receiver (TR) properly zeroed?
    A TR is zeroed when electrical zero voltages exist across its stator windings at the same time its rotor is on zero or on its mechanical reference position.
  63. What should a voltmeter read when a TX is set on coarse zero?
    Approximately 37 volts.
  64. What precaution should you take when you use 115 volts to zero a differential?
    Never leave the circuit energized for more than 2 minutes.
  65. Why should a synchro be rechecked for zero after it is clamped down?
    To ensure that it did not move off zero while it was being clamped.
  66. What is the output voltage of a CT when it is set on electrical zero?
    Zero or minimum voltage.
  67. When you zero a multispeed synchro system which synchro should you zero first?
    The coarse synchro.
  68. What method of zeroing a synchro is perhaps the fastest but NOT necessarily the most accurate?
    The electrical lock method.
  69. What restrictions are placed on the use of the electrical lock method?
    It can be used only if the leads of the synchro are accessible and the rotor is free to turn.
  70. When you zero a synchro with a synchro tester, what is indicated by a jump in the synchro tester's dial when the S1 and S3 leads are momentarily shorted?
    The synchro under test is not on electrical zero.
  71. What should you do with a synchro that has a bad set of bearings?
    Replace it.
  72. Name two types of trouble you would expect to find in a newly installed synchro system.
    Improper wiring and misalignment.
  73. What type of indicator is usually placed in the stator circuit of a torque synchro system?
    An overload indicator.
  74. What is the most probable cause of trouble in a synchro system that has all of its receivers reading incorrectly?
    The transmitter or main bus.
  75. If an ac voltmeter is connected between the S2 and S3 windings on a TX, at what two rotor positions should the voltmeter read maximum voltage?
    150� and 330�
  76. What precaution should you take when substituting a synchro tester in a circuit for a transmitter?
    Use only one receiver so as not to overload the tester.