Sodium Vapour Lamp

Sodium Vapour Lamp consists of a discharge tube made from a heat resistant glass, containing a little amount of in english metallic sodium, neon gas and two human resources manager electrodes, Neon gas is added to commence the discharge and to develop adequate heat to vaporize the sodium. Simply because of law pressure inside the tube, a sufficiently long tube required to acquire far more light. To reduce the overall dimension of the lamp, this tube is generally bent into U-shape.

The light made by this lamp is yellowish which is made at its optimum pressure of about .004mm of mercury. This pressure is obtained at a temperature of about 280 C and so it becomes required to sustain this temperature. For this objective the U-tube is enclosed in a double walled flask to avoid lose of heat. The double walled flask is interchangeable and can be fitted on to an additional U-tube. Whilst replacing the inner U-tube one particular should be very careful since if it is broken and sodium comes in contact with moisture, it may outcome in fire.

All electric discharge lamps demand a greater voltage at the time of beginning and low voltage throughout relevant webpage operation. Typically, 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 sufficient to start off the discharge. When the lamp is completely operative right after ten - 15 minutes, the voltage across it falls to about 150 volts. Due to the fact of the high reactance of circuit, the power element is low and therefore a p.f improvement capacitor is connected.

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