Sodium Vapour Lamp

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Sodium Vapour Lamp consists of a discharge tube produced from a heat resistant glass, containing a small quantity of metallic sodium, neon gas and two electrodes, Neon gas is added to begin the discharge and to create adequate heat to vaporize the sodium. Due to the fact of law pressure inside the tube, a sufficiently lengthy tube essential to obtain much more light. To minimize the overall dimension of the lamp, this tube is generally bent into U-shape.

The light produced 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 essential to sustain this temperature. For this objective the U-tube is enclosed in a double walled flask to analysis prevent shed of heat. The double walled flask is interchangeable and can be fitted on to another U-tube. While replacing the inner U-tube one particular must be follow us on twitter really careful since if it is broken and sodium comes in make contact with with moisture, it may possibly outcome in fire.

All electric discharge lamps demand a larger voltage at the time of starting and low voltage for the duration of operation. Usually, 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 adequate to start the discharge. When the lamp is totally operative after ten - 15 minutes, the voltage across it falls to about 150 volts. Since of the high reactance of circuit, the power factor chicken coopes critique is low and therefore a p.f improvement capacitor is connected.

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