step6quiz1tech

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scottmert
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19534
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step6quiz1tech
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2011-02-28 16:27:15
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Step6 Quiz1 Tech
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Step6 Quiz 1 Tech
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  1. Routine maintenance when performed 3-7 years is a cost effective way to determine equipment status.
    False
  2. What is an important tool for detecting over heating and arcing?
    DGA
  3. Describe Thermal Runaway:
    Excessive contact wear and carbon buildup increases contact resistance, causing more coking and more heating.
  4. Every ____ degrees C increase in tempurature _________ the rate of decay of winding insulation.
    7 Seven----Doubles
  5. The _______ causes more unplanned transformer outages and is considered the highest maintenance area on the transformer.
    L T C ---Load tap changer
  6. A temperature differential alarm could indicate a major temperature differential problem, such as off step, broken springs, severe arcing, etc.
    TRUE
  7. Under normal load, it is normal for the LTC to operate warmer than the main tank due to switching operations.
    FALSE
  8. What is an overcurrent within normal current paths?
    An Overload.
  9. To protect equipment from momentary overloads, the overcurrent device is designed to open the circuit quickly.
    FALSE
  10. A ______ is a one-shot device designed to open when a dangerously large current flows, for instance when a _______ ________ occurs.
    FUSE

    Short circuit
  11. A current limiting fuse will open how quickly when subject to a high level fault?
    1/2 cycle.
  12. Fuses and breakers can be used to open and close circuits manually or automatically.
    FALSE
  13. Explain a fuse's time current curve:
    The higher the fault current, the faster the fuse will open.
  14. What two current parameters define the current limiting range of an OCPD?
    THRESHOLD CURRENT and MAX INTERRUPT RATING
  15. If set too low, for arc fault protection, the instantaneous setting on circuit can cause ________ tripping as loads attempt to ________.
    NUISANCE

    START
  16. On time-current curves, the vertical axis represents:
    TIME IN SECONDS.
  17. Total Time to Clear (Tc) time equals:
    (Tm) melting time + (Ta) arcing time.
  18. On molded case panel breakers, the open under overload is sensed by a _______ Element, while on power circuit breakers a ________ _______ is generally used.
    THERMAL

    MAGNETIC COIL
  19. The time between when a breaker senses overload and the contacts begin to move apart is know as the:
    UNLATCHING TIME.
  20. Once a breaker unlatches what happens?
    The circuit opens.
  21. Dual element fuses are also known as ______ ______ fuses, and are designed to prevent in-rush currents or temporary overloads from opening the circuit, but will melt under continuous overloads or short circuits.
    Time Delay
  22. Number 1-9 in proper order, the sequence of events of an SMD power Fuse.
    • 5
    • 7
    • 9
    • 1
    • 3
    • 6
    • 8
    • 2
    • 4
  23. Maximum load current at the fuse location is typically the total _________ __________ ___________ measured in ______.
    Connected tranformer capacity

    (measured in) K V A
  24. Two fuse characteristic curves are:
    Minimum Melting Time and

    Maximum Clearing Time
  25. When a down-stream interrupting device interrupts a fault, the sectionalizer counter will:
    a) Reset count -wrong

    b) Not count - correct

    c) Count once - wrong
  26. Sectionalizers work with upstream, ___________ side protective devices such as reclosers and reclosing breakers.
    Source
  27. Sectionalizers do not open ________ current, but counts it and opens during the ____ ________ interval of the upstream device
    Fault

    open voltage
  28. ANSI Device numbers for instantaneous and time overcurrent relays:
    50

    51
  29. The instantaneous overcurrent trip is used in a _______ _________ scheme to allow the PCB to open prior to the melting time of the fuse.
    Fuse Saving
  30. PCB reclosing function is provided by the _____________ Relay, device number ______.
    Reclosure

    79
  31. The purpose of the time delay of reclosing is to allow ___________________________ and _______________________________.
    PCB closing spring to recharge

    The ionization gases to dissipate to prevent re-arcing of the gases.
  32. The acceptable voltage tolerance to our customers is _________ %.
    + or - 5 %
  33. Three influences on distribution feeder impedance /voltage are:
    Capacitance

    Inductance

    Resistance
  34. Voltage and turns ratio are __________ proportional.
    Directly
  35. A traditional transformer becomes an ________ -Transformer when their windings are connected to either aid or oppose one and anouther.
    AUTO
  36. The low voltage windings are known as the ________ windings, and contain taps.
    The high voltage winding is known as the regulated or _________ winding.
    Series

    Shunt
  37. The bridging _________ limits the circulating current caused by the contacts being at different positions.
    Reactor
  38. The ____ _____ ________ allows the regulator to maintain a constant voltage at a remote load center.
    Line

    Drop

    Compensator
  39. 32-step regulation provides an overall full _____ % voltage regutation.
    20 %

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