SODIUM VAPOUR LAMP

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SODIUM VAPOUR LAMP:

Sodium Vapour lamp 1s a type of cold cathode gas discharge lamp.

Construction

This type ot lamp consists of two U shapped hard glass evaluated tubes

as shown in ligure. Inner glass tube is filled with sodium cristals and small

quantity of neon gas. The Oxide coated tugusten filament is fitted at both ends.

This lamp is affected greatly by change in temperature, it is placed in another

evacuated glass tube and bayonet cap is provided for the fixing lamp in theholder to give supply.

.

Working

Sodium vapour lamp is a cold cathode low pressure discharge lamp gives

high luminous out put. To start this lamp high voltage about 380 volt to 450

volt is required which is given by spencial tyype of transformer known as

reactance transformer. This transformer gives higher voltage at starting and

hoke after glowing of lamp stabilized voltage at 110 V. To adjust poor voltage

d a regulation and to improve power factor, a capacitor is connected across the

and supply. This lamp gives radish light due to discharge of neon gas. When sodium

rode crystals turn to vapour, the lamp gives bright yellow-pink tight with high

and uminous intensity. This lamp is used with following essential aspects.

(1) It should be used only in horizontal position.

(2) It should be used only on A.C. supply.

3) It takes 5 to 10 minutes to give full luminous output.

Applications

(1) It is normally used in street lighting, sea shore lighting. sheep ya

etc.

(2) Available ratings are 60, 80, 125, 250 watts.

(d) Compact Fluorescent Lamp (C.F.L. Lamp)

It is a modified form of fluorescent tube having all the positive features

an ordinary bulb and tube light. It is also known as C.L.F. lamps. Figu

shows the different shapes and sizes. These are also available in diferer

ranges. CFL lamps posses following specialities.

(1 It consumes approximately 80% less electricity than other lamps

(2) It' s working lite is about 5 to 6 times greater than other latnps.

(3) These are available in varieties of wattage, 3 W, 5 W. 7 W, 9 W. 11

W, 15 W, 20 W, 23 W, 40 W etc.

(4 Comparison of filament lamp with CFL for same luminous out put