Vital or Hot Bus - Defence Aeroskills Training Academy Quiz
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Questions and Answers

What is the term used to refer to the number of cycles of AC that occur every second?

  • Ampere
  • Volt
  • Hertz (correct)
  • Kilowatt

    • In aircraft, what is the standard frequency for AC power supply?

  • 400 Hz (correct)
  • 1000 Hz
  • 50 Hz
  • 60 Hz

    • What type of AC waveform is represented by a single sine wave?

  • Single-phase (correct)
  • Three-phase
  • Multiphase
  • Polyphase

    • Which term refers to the electrical bus that is non-essential for flight?

    <p>Non-essential bus</p> Signup and view all the answers

    How does the frequency of AC power impact aircraft equipment?

    <p>Increases output power</p> Signup and view all the answers

    What is the primary function of an inverter in an aircraft electrical system?

    <p>Convert DC voltage into AC voltage</p> Signup and view all the answers

    In the event of all AC generators failing, how are essential aircraft electrical systems powered?

    <p>By an inverter</p> Signup and view all the answers

    What is the main difference between rotary and static inverters in aircraft electrical systems?

    <p>Static inverters are solid state electronic devices</p> Signup and view all the answers

    Why is supplying aircraft with external AC power essential on the ground?

    <p>To avoid running the engines for AC generation</p> Signup and view all the answers

    What does a TRU do in an aircraft electrical system?

    <p>Converts AC into DC</p> Signup and view all the answers

    What determines the output frequency of an aircraft's AC generator?

    <p>Engine speed</p> Signup and view all the answers

    Which component ensures that the generator's output frequency is maintained close to 400 Hz?

    <p>Constant Speed Drive Unit (CSDU)</p> Signup and view all the answers

    What function does the Generator Control Unit (GCU) perform?

    <p>All of the above</p> Signup and view all the answers

    What is the main purpose of Transformer Rectifier Units (TRUs) in an aircraft's power supply system?

    <p>Convert AC to DC</p> Signup and view all the answers

    In an aircraft's AC system operation, what ensures that the generator's frequency output remains stable even if the engine speed varies?

    <p>Constant Speed Drive Unit (CSDU)</p> Signup and view all the answers

    What is the main advantage of using Alternating Current (AC) over Direct Current (DC) in aircraft power supply systems?

    <p>AC generators do not require a commutator and brushes like DC generators, reducing complexity and eliminating arcing of brushes.</p> Signup and view all the answers

    In an aircraft, what design feature of AC generators makes them ideal for high altitude flight?

    <p>Elimination of arcing of brushes by not requiring a commutator in the generator design.</p> Signup and view all the answers

    What feature of AC allows it to achieve higher electrical efficiency in comparison to DC in aircraft systems?

    <p>Transmission with lower electrical losses due to its nature compared to DC.</p> Signup and view all the answers

    What component allows AC power in aircraft to be adjusted as required for different equipment?

    <p>Transformers that can step up or down the AC voltage.</p> Signup and view all the answers

    Why are AC generators preferred over DC generators in aviation applications?

    <p>AC generators eliminate arcing of brushes by not requiring a commutator, reducing complexity.</p> Signup and view all the answers

    What is the fundamental operation for an AC tied bus system?

    <p>Starting number 2 engine and synchronising it with number 1 generator.</p> Signup and view all the answers

    What are the components of a tied bus system?

    <p>Generator Circuit Breakers (GCBs), Bus Tie Breakers (BTBs), Frequency control adjustment, Voltmeter.</p> Signup and view all the answers

    How is the synchronization of number 2 generator to number 1 generator achieved in an AC tied bus system?

    <p>By fine adjusting the frequency and voltage of number 2 generator.</p> Signup and view all the answers

    What happens after number 2 generator is synchronized to number 1 generator in an AC tied bus system?

    <p>Number 2 generator is connected to the AC distribution system by closing number 2 GCB.</p> Signup and view all the answers

    Which system uses GCBs and BTBs with the same construction as the ones used in a split bus system?

    <p>AC tied bus system.</p> Signup and view all the answers

    What is the main purpose of a current limiter in a generator system?

    <p>To reduce the generator output voltage when a safe load is exceeded</p> Signup and view all the answers

    What will happen if an aircraft generator's armature burns out due to excessive current flow?

    <p>The batteries will overcharge</p> Signup and view all the answers

    When would a Transformer Rectifier Unit (TRU) be used as a secondary DC supply in an aircraft?

    <p>When the AC generating system fails</p> Signup and view all the answers

    What is the primary function of an RCR in an aircraft electrical system?

    <p>To prevent overcharging of the batteries</p> Signup and view all the answers

    How does a Transformer Rectifier Unit (TRU) contribute to an aircraft's power supply?

    <p>By converting power from AC to DC</p> Signup and view all the answers

    If a DC generator operating within limits supplies the essential bus with a regulated 28 VDC, what action does the RCR take if the generator fails?

    <p>Disconnects the generator from the essential bus</p> Signup and view all the answers

    Which bus in an aircraft would typically power some lighting systems and mission control when a generator fails?

    <p>Non-essential bus</p> Signup and view all the answers

    In an aircraft, what role does the essential bus play in the DC distribution system?

    <p>Re-distributes power to all loads</p> Signup and view all the answers

    If an AC waveform is represented by a single sine wave, what type of waveform does it indicate?

    <p>Sinusoidal wave</p> Signup and view all the answers

    When an aircraft's AC power frequency increases, how does it impact the operation of equipment connected to it?

    <p>Alters performance characteristics</p> Signup and view all the answers

    What action does the RCR take if a DC generator fails and its output voltage remains above the battery's voltage?

    <p>Disconnects the generator from the essential bus</p> Signup and view all the answers

    Which term describes an electrical bus that is necessary for aircraft operation?

    <p>Essential bus</p> Signup and view all the answers

    What component disconnects a DC generator from the essential bus when it fails?

    <p>RCR</p> Signup and view all the answers

    If an AC system operates with a sawtooth waveform, what does this indicate about its output?

    <p>It is pulsating and irregular</p> Signup and view all the answers

    What type of electrical wave has a triangular shape and is commonly used in certain AC applications?

    <p>Triangular wave</p> Signup and view all the answers

    Study Notes

    Tied Bus Distribution System

    • A tied bus AC distribution system includes GCBs, BTBs, CSDUs, frequency control adjustment, GCUs, voltmeter, and frequency meter.
    • The system operates by starting and synchronizing generators, then bringing them online by closing GCBs.

    Generator Circuit Breaker (GCB) and Bus Tie Breaker (BTB)

    • GCBs and BTBs used in a tied bus system are the same construction as those used in a split bus system.

    AC System Operation

    • AC waveform is a single-phase sine wave that periodically rises and falls on a regular time basis.
    • Frequency is the number of cycles of AC that occur every second, and aircraft AC equipment requires a constant frequency of 400 Hz.

    Transformer Rectifier Units (TRUs)

    • TRUs convert AC generator output into 28 VDC required for the aircraft's DC loads.
    • TRUs can be used as the primary DC supply or as a secondary DC supply if a DC generator fails.

    Inverters

    • Inverters change DC voltage into AC voltage, and can be used as a primary AC supply in aircraft with DC generators.
    • Inverters can also be used as a backup power supply if all AC generators fail.

    External Power Supply

    • External power supply is essential for engine starting and servicing, and is usually provided by a constant frequency AC generator.
    • Larger aircraft require only AC external power, while smaller aircraft typically use DC external power only.

    Constant Speed Drive Unit (CSDU)

    • CSDU ensures the output frequency of the generator is maintained close to 400 Hz, despite engine speed variations.

    Generator Control Unit (GCU)

    • GCU performs functions such as voltage regulation, current limiting, system protection, and crew alerting.

    Advantages of Alternating Current

    • AC has advantages over DC, including simpler generator design, higher electrical efficiency, and the ability to be stepped up or down by transformers.

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    Description

    Test your knowledge on the Vital or Hot Bus concept with this quiz from Defence Aeroskills Training Academy. Explore key information related to the topic. Official Use Only.

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