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Mercury Discharge Lamps

Mercury Discharge Lamp Applications

High pressure mercury lamps provide a cool, white light, with adequate coour rendering qualities for use in utility projects such as street lighting, forecourt and amenity lighting.

Mercury Discharge Construction

Glassware

  • Outer jacket is soft glass (up to 80w), hard glass (125w and over) both types are internally coated with phosphor
  • Discharge tube is quartz

Cap type - E27 (up to 125w), E40 (250w and over).

Phosphor Mix - Yttrium vanadate is used for the internal coating which converts the UV into visible light, colour appearance 3500oK.

Gas Filling - Space between outer jacket and discharge tube is filled with inert gas at low pressure.

Starting and Operation

Starting Method - An initial discharge is started between a primary and an auxiliary electrode. The resulting electrons are drawn down the arc tube to the other main electrode and the mercury arc is established.

Operation - Once the main arc is struck the heat produced further vaporises the merucy and the full mercury discharge reaches stability after approx 4 mins.

Restrike - Allow to cool - 4 minutes

Operating Position - Elliptical and reflector - universal -20oC minimum starting temperature

Physical Characteristics

Colour - white

Correlated Colour Temperature = 3500oK

Colour Rendering Index (Ra) / Group = 55/3

Chromaticity co-ordinates - x = 0.410y = 0.390

Efficacy - up to 60 lm/w

 

Source : Crompton Lamps