High Pressure Sodium Vapour Lamps Quiz
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Questions and Answers

Which type of lamp is no longer commonly used due to its obsolescence?

  • Compact Fluorescent
  • Mercury Liner Fluorescent (correct)
  • Metal Halide
  • Standard Incandescent
  • What is the defining feature of High Intensity Discharge (HID) lamps?

  • They consist of an arc tube enclosing two electrodes. (correct)
  • They are energy efficient due to their low-pressure composition.
  • They emit light through incandescence.
  • They do not require a ballast for operation.
  • Which type of lamp requires a ballast to strike and hold the arc inside it?

  • Compact Fluorescent
  • Standard Incandescent
  • Metal Halide (correct)
  • Low pressure Solid state /LED
  • What is the purpose of the run-up time in an HID lamp?

    <p>To measure the time needed for the lamp to reach full light output</p> Signup and view all the answers

    Why are High Pressure Sodium Vapour Lamps also referred to as HID lamps?

    <p>High Intensity Discharge (HID) lamps are an alternate name for them</p> Signup and view all the answers

    Study Notes

    Applications of Lamps

    • Utilized primarily in street lighting and high-bay installations (high-roofed areas).
    • Dimming capability available with appropriate ballast.

    High Pressure Sodium Vapor Lamps

    • Superior luminous efficacy ranging from 70 to 130 lumens per watt (lm/W).
    • Low Color Rendering Index (CRI).
    • Lifespan approximately 20,000 hours.
    • Requires a ballast for operation, commonly an electromagnetic ballast.
    • Power factor correction capacitor is utilized.
    • Correlated Color Temperature (CCT) at 1950K.
    • Available wattages: 70W to 400W.
    • Offered in tubular and elliptical shapes.

    Operation of High Pressure Sodium Vapor Lamps

    • Discharge tube made from Poly Crystalline Alumina, a durable ceramic.
    • External ignitor used to provide initial starting voltage.
    • Contains sodium, excess mercury, and xenon for efficient ignition and reduced heat conduction.
    • Main discharge primarily occurs in the visible range, minimal ultraviolet (UV) emission.

    High Pressure Mercury Vapor Lamps

    • The original High-Intensity Discharge (HID) lamp technology.
    • Efficacy ranges from 35 to 65 lm/W.
    • Lifespan of around 12,000 hours.
    • Like sodium lamps, requires a ballast for operation with a power factor correction capacitor.
    • Available CCTs are 4000K and 6500K.
    • Wattages available range from 80W to 400W.

    Operation of Mercury Vapor Lamps

    • Discharge occurs in a quartz tube containing a small amount of mercury and inert gas to facilitate starting.
    • Contains a fluorescent coating that converts UV radiation to visible light.
    • Run-up time to achieve 80% light output is approximately four minutes.
    • Three critical operational phases are Ignition, Run Up, and Stabilization:
      • Ignition: Initiated by a starting electrode and a high voltage gradient causes a glow discharge.
      • Run Up: Lamp does not reach optimal light output until all mercury is vaporized.
      • Stabilization: Achieved once full brightness is reached after the run-up phase.

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    Description

    Test your knowledge on high pressure sodium vapour lamps used in street lights and highbays. Learn about their luminous efficacy, color rendering index, life span, and the need for a ballast for operation. Explore the characteristics and applications of these lamps.

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