Systems 1 DC Circuits

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  1. Resistance in relation to Temp, Length, and cross sectional area of the conductor.
    • Proportional to Temp and Length
    • Inversely proportional to Cross sectional area
  2. State Ohms law
    V = IR

    Voltage = Amps x Resistance.
  3. State both equations for Power
    P = VI

    P = IR
  4. State Kirchoffs Law
    I1  =   I2   +    I3
  5. Primary and Secondary cells are also known as what?
    Primary - non Rechargeable

    Secondary - Rechargeable
  6. In an Primary (Dry) Cell, what are the positive core, Negative case, and electrolyte made of?
    Positive - Carbon

    Negative - Zinc

    Electrolyte - Ammonia Chloride paste
  7. In an Secondary Cell, what are the positive core, Negative case, and electrolyte made of?
    Positive plates of Lead Peroxide

    Negative plates of Lead

    Dilute Sulphuric Acid
  8. How many volts will a Lead Acid Cell produce?
    2.1 volts max
  9. How long is the standard discharge period when testing the capacity of batteries?
    10 hours
  10. How long should a voltmeter show the rated voltage of the battery when a test load is put in parallel if the battery is healthy?
    Should show rated voltage for 15sec
  11. What should the SG range be in a fully charged lead acid battery?

    What will SG be when fully discharged?
    Charged 1.25 - 1.30

    Discharged 1.17
  12. In an Alkaline NiCad Battery what are the positive and negative plates, and the Electrolyte made of?
    Positive - Nickel Hydroxide

    Negative - Cadmium Hydroxide

    electrolyte - Distilled water and potassium Hydroxide
  13. Advantages of NiCad over Lead Acid
    Smaller, Lighter, more Robust

    Last Longer (more charge-discharge cycles)

    Better performance at low temps

    voltage remains constant through whole discharge cycle

    Can be left fully discharged
  14. How many volts per cell do Nicads produce?
  15. Disadvantages of Lead Acid Batteries
    Give off Oxygen and Hydrogen while being charged

    Cant be left in a discharged state or lead sulphate coats the plates and stops charge being accepted
  16. disadvantages of Nicad batteries
    Low thermal capacity so prone to thermal runaway when being charged
  17. When connecting batteries in Series, what happens to the rated capacity, and to the voltage
    Rated Capacity remains the same

    voltages are summed
  18. When connecting batteries in Parallel, what happens to the rated capacity, and to the voltage
    Rated Capacity is summed

    Voltage remains same as for a single battery
  19. How is the ground power relay powered from the 3 pin receptacle?
    From the shorter of 3 pins so it cuts power before the other 2 longer pins come out and cause possible arcing
  20. Name the 3 typical requirements of an aircraft electrical system
    1) Supply to all equipment must be maintained unless total demand exceeds available supply

    2) Systems faults should have the least possible effect on overall system functioning

    3) A fault on one piece of equipment should not affect the power supply to the others
  21. What are Vital consumers?
    Services required in an emergency when all main power sources are lost. Emergency lighting, fire detection etc. Connected Directly to battery supply
  22. What are essential consumers?
    Necessary for safe flight in an emergency situation. Connected to bus bar than can be supplied by Gen or Batt
  23. what are Non-Essential consumers?
    Can be safely disconnected during in-flight emergency for purposes of load shedding. Supplied from the Gen bus
  24. At what voltage will over-volt protections typically kick in with a 12v system?
  25. How many degrees of motion does a rotary actuator typically move through?

    fuel cocks, hydraulic rotary valves, butterfly valves etc
  26. What is the active component of a circuit breaker, and what is a difference between "trip-free" and "non trip-free"
    Bimetallic strip

    Trip-free cant be held in to make the circuit
  27. Static wicks are made of what
    Carbon or Copper
  28. What is the bonding component in conducting tyres
    Carbon - normally only nosewheel
  29. What re-fueling flow rate could produce static electricity
    5000l/min or more.

    In over wing refueling nozzle must touch airframe as fuel exciting can cause spark.
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Systems 1 DC Circuits
2013-07-16 01:38:09
DC Circuits

DC Circuits
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