High Pressure Sodium Vapour Lamps Quiz

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.