Voltage and Frequency Regulation

Card Set Information

Author:
antoan
ID:
197169
Filename:
Voltage and Frequency Regulation
Updated:
2013-02-08 16:24:26
Tags:
EM study guide
Folders:

Description:
Chapter 8 EM rating manual
Show Answers:

Home > Flashcards > Print Preview

The flashcards below were created by user antoan on FreezingBlue Flashcards. What would you like to do?


  1. Refer to table 8-1 in your textbook. What type of electrical power has the most stringent voltage and frequency requirements?
    Type II 
  2. Type III power is normally produced by what means?
    Motor generator sets
  3. The automatic voltage regulator maintains the generator’s output voltage by regulating the dc through what part of the static exciter?
  4. The control winding
    (i think)
  5. What factor determines the magnitude of the generated voltage of an ac generator?
    Strength of the field flux
  6. Which of the following methods is normally used to provide voltage control in a dc generator?
    The strength of the generator shunt field is varied
  7. In the direct-acting rheostatic voltage regulator, what part exerts a mechanical force directly on a special type of regulating resistance?
    Regulator coil 
  8. In what configuration, if any, is the voltage regulator connected to the shunt field of the exciter?
    In series
  9. The silver buttons in a Silverstat voltage regulator are connected to taps on what component(s)?
    Regulating resistance plates
  10. The range covered by each voltage-adjusting rheostat of the regulator can be set so the rheostat’s midposition is in the normal operating position to obtain the rated generator voltage. What component should you adjust to set the range?
    Resistors connected in series with the regulator coil
  11. In what configuration is the primary of the damping transformer connected in a regulator that controls a large ac generator?
    Across the output of the exciter
  12. In what way does a direct-acting voltage regulator respond to a decrease in generator load?
  13. The regulator armature is pulled toward the regulator coil, more silver buttons are spread apart, and the regulating resistance increases
  14. You are switching a direct-acting voltage regulator system from manual to automatic control. It is necessary for you to leave the control switch in the TEST position momentarily to allow which of the following actions to occur?
    The damping transformer transient current to die down
  15. The moving arm of a direct-acting regulator will behave in what way if the damping transformer connections are reversed?
  16. The voltage regulator transfer switch for two generators (A and B) is in the GEN B position. The voltages of the generators are controlled in what way?
    Generator A is controlled by its own regulator, and generator B is controlled by the standby generator
  17. The stabilizer functions to prevent hunting in the voltage regulator circuit. It does this by what means?
    It aids any change in the amplidyne control field current

    ( i think)
  18. When the number of saturated reactor coil turns in the voltage adjusting unit is decreased, the inductance of the saturated reactor reacts in what way?
    It decreases, and the voltage held by the regulator is lowered
  19. What unit provides the regulator with a signal proportional to the ac generator voltage?
    The potential unit
  20. If the generator voltage is near normal in the automatic control circuit, buck circuit current from F2 to F1 in the amplidyne control field has what magnitude?
    Nearly equal to the boost circuit current
  21. By what means does the automatic control circuit oppose an increase in ac generator voltage?
    The saturated reactor current increases, causing an increase in the amplidyne control field current

    (i think)
  22. A decrease in generator frequency affects the reactance of the saturated reactor and the frequency compensation circuit in what way?
    The reactance of the saturated reactor decreases, and the frequency compensation network behaves like an inductance
  23. At unity power factor, the compensating voltage across the compensating potentiometer rheostat is in phase with what voltage?
    Voltage across the teaser leg of the T-connected potential transformer secondary
  24. Two generators are placed in parallel operation in a rotary voltage regulator system. By what means are the load distribution and power factor adjusted?
    The voltage-adjusting unit and prime mover governors

    ( i think)
  25. You should check the amplidynes’ short-circuiting brushes periodically for what reason?
    Improper brush contact may result in an excessively high amplidyne voltage output
  26. Switches S1 and S2 contain a large number of series-connected contacts for what reason?
    To eliminate arcing when turned to the OFF position
  27. The output of the static exciter is controlled by the current through what circuit component(s)?
    Transformer control windings 
  28. The automatic voltage regulator maintains the generator’s output voltage by regulating the dc through what part of the static exciter?
    The secondary winding

    (i think)
  29. The reactance value of L6 in the voltage regular depends on what other value?
    The output of CR 
  30. Each magnetic amplifier is operated in the center portion of its magnetic core saturation curve by adjusting what components?
    R14 and R15
  31. The initial field current for starting the ac generator is provided by which of the following components?
    1. The static exciter 2. The output rectifiers 3. A 50 kW, dc generator 4. Each of the above

    • (i think)
  32. The steady state and transient frequency requirements for type II power can be met with electro-hydraulic governors. However, a motor generator or static converter will still be required for what type of voltage control?
    III
  33. The purpose of the SPR-400 line voltage regulator is to ensure precision control of variations in which of the following factors?
    1. Line voltage 2. Load changes 3. Power factor 4. All of the above
  34. If there is a decrease of the dc in the control winding, what is the effect of the (a) voltage of the opposing winding and (b) output of the autotransformer?
    (a) Increases (b) decreases
  35. Refer to figure 8-20 in your textbook. The purpose of potentiometer R21 is to compensate for what factor?
    The resistance in the cables from the regulator to the load
  36. You should frequently inspect the SPR-400 line voltage regulator for which of the following possible causes of improper operation?
    1. Dust 2. Dirt 3. Moisture 4. All of the above
  37. What means is used to control the output of the static exciter?
    The output of the power section of the regulator acts on windings within the static exciter
  38. What means are used to control the SCRs in the power circuit?
    By using an amplified error signal that is developed in the reference bridge and fed through a unijunction transistor circuit
  39. What means is used to provide the no-load field excitation to the motor-generator set?
    The rectified output of the secondary windings of the SCPT
  40. Variations in generator output frequency is compensated for the
    drive motor current being increased or decreased
  41. By what means does the voltage act to regulate converter output voltage?
    By controlling the firing time of the main SCR in each inverter
  42. In mode 1 operation, what drives the ac end of the motor generator?
    The ship’s service power supply
  43. The K1 relay is energized for which of the following examples of phase angle (θ), voltage difference (∆V), and frequency difference (∆F)?
    θ= + 5°, ∆V = 5%, ∆F = 2.0 Hz 

    (i think)
  44. The synchronizing monitor is connected to a circuit consisting of two generators and the K1 relay is energized. In what way does this configuration affect the parallel operation of the generators?
  45. The reference bias voltage for Q1 in the synchronizing monitor appears across what component?
  46. The phase difference circuit turns Q1 off as a result of what action?
  47. The voltage difference circuit turns off as a result of what action?
    Base-to-emitter short caused by the conduction of Q5
  48. Refer to figure 8-34 in your textbook. Which of the following components in the frequency difference monitoring circuit are connected so that a beat frequency voltage is produced between the oncoming generator and the bus?
    Secondaries of T2 and T3
  49. When occurring simultaneously with the indicated bus voltage, what generator voltage will produce the maximum current flow in CR10 in the phase difference monitoring circuit of the synchronizing monitor?
    A
  50. Refer to figure 8-35 in your textbook. This figure shows the results of various steps in the generation of a signal that is used to fire SCR1 in the frequency difference monitoring circuit. What is the purpose of the step that produces the waveform shown in diagram E?
    To assure that the clipped signal goes to zero when the original beat frequency voltage goes to zero
  51. A unijunction transistor has 0 volts on base 1 and 12 volts on base 2. If the transistor fires when the base 1-to-emitter voltage reaches 8 volts, the transistor has what etavalue (intrinsic standoff ratio)?
  52. Study Hint: Assume that the difference in frequency between the oncoming generator voltage and the bus voltage is 0.2 Hz. 8-51.

    What is/are the time constant period(s) for one cycle of the beat frequency voltage?
    5.0
  53. What is the function of the frequency differential circuit?
  54. By which of the following means is Q2 controlled?
  55. In the voltage difference monitoring circuit, the K1 relay will not close if the voltage difference in the generators is more than what specified percentage?
    5%
  56. The difference in the magnitude of the sensing signals from the oncoming generator and the bus is detected in what bridge circuit component?
  57. What is the purpose of R19? 
    To prevent large voltage variations 
  58. High-power transistors that are noticeably hot while operating have been damaged beyond use.
  59. When using a signal generator as a transistor tester, what is the first connection you should make?
    Connect the power line to an isolation transformer
  60. What action should you take to prevent damage to a transistor?
    Use isolation transformers to protect transistors from test equipment
  61. Multimeters that are used for voltage measurements in transistor circuits should have what minimum high ohms/volt sensitivity?
    20,000 ohms/volt
  62. Ohmmeters will damage transistors if the meters have a range that is greater than what maximum amperage?
    1.00 mA

What would you like to do?

Home > Flashcards > Print Preview