Sodium Vapour Lamp

出典: くみこみックス

Sodium Vapour Lamp consists of a discharge tube created from a heat resistant glass, containing a modest quantity of metallic sodium, neon gas and two electrodes, Neon gas is added to start the discharge and to create enough heat to vaporize the sodium. Since of law pressure inside the tube, a sufficiently long tube essential to obtain much more light. To reduce the overall dimension of the lamp, this tube is normally bent into U-shape.

The light made by this lamp is yellowish which is created at its optimum pressure of about .004mm of mercury. This pressure visit free chicken coops is obtained at a temperature of about 280 C and so it becomes necessary to sustain this temperature. For this objective the U-tube is enclosed in a double walled flask to avoid shed of heat. The double walled flask is interchangeable and can be fitted on to yet another U-tube. Although replacing the inner U-tube one should be extremely careful due to the fact if it is broken and sodium comes in contact with moisture, it might result in fire.

All electric discharge lamps need a higher voltage at the time of beginning and low voltage for the duration of operation. Generally, sodium vapour lamps are operated by a high leakage reactance transformer. At beginning a high voltage of about 450 volts is applied across the lamp which is enough to start off the discharge. When the lamp is completely operative the guide to backyard chicken coop open site in new window following 10 - 15 minutes, the voltage across it falls to about 150 volts. Since of the high reactance of circuit, the power issue is low and hence a p.f improvement capacitor is connected.

The efficiency of a low pressure sodium vapour lamp is really high (about 40 - 50 lumens/watt) and it produces a light of distinct wavelength obtaining yellow color. Sodium lamps are mostly employed for street, high way and airfield lighting where color distinction is not so needed.