Sodium vapour lamp

Sodium vapour lamp construction , working of sodium vapour lamp, advantages and disadvantages of sodium vapour lamp, explanation of sodium vapour lamp, what is sodium vapour lamp, application of sodium vapour lamp . All information covers in this ppt.

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2. Sodium vapour lamp Explanation Full detail by Amardeep jha

3. Working Principle of Sodium vapour lamp Electron are emitted from cathode by subjecting the surface of cathode to very high electric stress so that the electrons are forcibly ejected from the orbits of atom against nuclear centripetal force.

4. Sodium vapour lamp construction :- It consist of inner tube of U - shape is fitted with neon gas and globules of sodium . For good performance , 300 degree centigrade temperature is to be maintained . To protect discharge tube it is contained in evacuated double walled glass jacket. This prevent heat loss . At starting , electric discharge is to be established through neon gas till sodium gas vapourized so at start of 10-15 min . discharge through lamp will be pink then as sodium vapourizes , it will turn into yellow . For this voltage of about 410 is required white normal voltage is about 165. Supply is given through the leak transformer which has a high leakage reactance. As soon a discharge through the tube start, heavy voltage drop take place in the transformer so that required operating voltage is automatically impressed across the cathode . Power factor of these lamps is 0.3 lagging and therefore condenser can be used for power factor connection.

5. Sodium vapour lamp :- Advantages: Most energy efficient among all artificial light sources. Very long life span up to 50000 hours. Color temperature is always warm . They are ideal for using at airports, seaports, streets, railway marshalling yard and crossings etc Disadvantages: Only monochromatic color. Bad color rendering index Unusable for color recognition places. Sodium is hazardous and can catch fire in contact of air

6. Some Important things :- Precaution : Care should be taken in handling these lamps for example, if inner tube is broken and sodium comes in contact with moisture , Fire will result . Life : Life of a sodium vapour lamp is avergly 2500 hours , Application : Due to yellow light its uses is limited in street lighting, flood lighting of docks, quarries etc. Size available : 45, 60, 85, 140 W.

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