Sodium lamps: general information


General information about sodium lamps

The discharge in sodium vapors depending on their pressure during the work of the lamp can radiate or monokhromaticheyosky, i.e. one-color, yellow light, or light, soderyozhashchy beams of different flowers and creating quite udovyoletvoritelny color rendition. Distinguish sodium lamps of low and high pressure.

Схема устройства натриевой лампы

Scheme of the device of the sodium lamp.

Sodium lamps low davleyoniya

Design of the natriyeyovy lamp: by both ends of the U-shaped tube made of the special borosilicate glass steady against influence of vapors of sodium oxidized electrodes are sealed.

The tube is filled with sootvetstyovuyushchy quantity металлическо­го sodium and inert gases — neyoony and argon. The digit tube is located in the protective shirt from transparent glass, obespechivayuyoshchy thermal insulation of the digit tube from fresh air and the podyoderzhaniye of the optimum temperatuyora at which heat losses are insignificant. In the protective rubashyoka it has to be created high ва­куум as lamp efficiency depends on the size and the podyoderzhaniye during work of the lamp of the vacuum. On the end of the outside tube the socle, usually shtifyotovy, for accession to network is strengthened.

Схемы подключения натриевых ламп высокого давления

Schemes of connection of sodium lamps of high pressure.

At first at ignition of the sodium lamp there is the discharge in neon, and the lamp begins to shine red light. Under the influence of discharge in neon the digit tube heats up and sodium begins to melt (the temperayotura of melting of sodium of 98 °C). The part of the melted sodium evaporates, and in process of increase in pressure of payor of sodium in the digit tube the lamp begins светить­ся with yellow light. Process of the razgoraniye of the lamp prodolyozhatsya 10 — 15 min.

Sodium lamps belong to the most ekonomichyony of the existing light sources. The number of factors exerts impact on the efficiency of the lamp: temperature of the digit tube, heat-insulating properties of the zashchityony shirt, pressure of gases-fillers, etc. For obtaining the largest efficiency of the lamp temperature of the razyoryadny tube has to be maintained in limits of 270 — 280 °C. At the same time the vapor pressure of sodium makes 4*10-3 mm Hg. Increase and fall of temperature against optimum leads to decrease in efficiency of the lamyopa.

For preservation of temperature of the digit tube at optimum level it is necessary to izoyolirovat better the digit tube from the surrounding atmosphere. The removable zashchityony tubes applied in domestic lamps do not provide sufficient heat insulation therefore the lamp made by our industry like DNA-140, 140 W, has light return of 80 — 85 lm/W. Sodium lamyopa at which the protective tube represents the single whole with the digit tube are now developed. Such konyostruktion of the lamp provides good heat insulation and together with improvement of the digit tube puyoty devices of dents on it gives the chance to lift light return of lamps to 110 — 130 lm/W.

Pressure of neon or argon has to be no more than 10 mm Hg., as with their more high pressure moving of vapors of sodium to one of the parties of the tube can be observed. It leads to decrease in efficiency of the lamp. For prevention of movement of sodium dents are provided in the lamp on the tube.
Service life of the lamp is defined by quality of glass, pressure of the filling gases, the design and mateyoriala of electrodes, etc. Under the influence of hot the nayotriya, especially its vapors, glass is exposed to the severe erosion.

Сравнительная шкала температур ламп

Comparative temperature scale of lamps.

Sodium — strong chemical reducer therefore, connecting to the making glass basis, silicon acid, it recovers it to silicon, and glass blackens. Besides, glass absorbs argon. Eventually in the digit tube there is one neon, and the lamp ceases to be lit. The average term of service of the lamp makes from 2 to 5 thousand h.

The lamp joins in network by means of the avtotransforyomator with big dispersion which provides high tension of no-load operation, necessary for ignition of the lamp, and stabilization of discharge.

The main lack of sodium lamps of low pressure — homochromatism of radiation that does not allow
to use them for the purposes of the general oveshcheniye under production conditions, because of considerable distortion of color of objects. Very effectively primeyoneny sodium lamps for lighting, transport access roads, highways and in some cases outside aryokhitekturny lighting in the cities. The domestic industry releases sodium lamps in ograniyochenny quantity.

Sodium lamps high davleyoniya

On appearance they napominayot lamps like DRL. In the steklyanyony flask having the elliptic or tsilindricheyosky form the digit tube with two electrodes and conclusions attached to the rezboyovy socle is placed. Unlike sodium lamps of low pressure these lamps radiate pleasant golden бе­лый light. Glass cannot be used for the izgoyotovleniye of the tube of sodium lamps of high pressure owing to very strong effect of vapors on it the nayotriya. As material polycrystalline oxide of aluminum is applied to production of the razryadyony tube (polikor).

Схема сравнения натриевых ламп

Scheme of comparison of sodium lamps.

Very pure powder of oxide the alyuyominiya is formed in the form of the tube and sinters at the vysoyoky temperature. The tube from polybark misses up to 90% of visible radiation and is very steady against influence of vapors of sodium. For the 400 W lamp the tube has the inside diameter of 7,5 mm and length of 80 mm. Inputs in the digit tube are carried out from the moyolibden. Electrodes on the ends of these tubes predstavyolyat themselves the molybdenic core with wound on it спи­ралью from tungsten.

Along with sodium are entered argon for simplification of ignition into the digit tube and mercury for increase in light return of the lamp. In the worker of the sostoyayoniya the vapor pressure of mercury makes from 2 to 20 ат. In neyokotory samples of lamps xenon was entered into the tube with the pressure of 20 mm Hg., what increases its light return.

Unlike sodium lamps of low pressure in lamps of high pressure the maximum of light return takes place at the vapor pressure of sodium of 200 mm Hg. Light return makes from 90 to 110 lm/W, and service life of 3 — 6 thousand h.

For obtaining high light parameters of nayotriyevy lamps it is necessary to podderzhiyovat the thermal mode very carefully. Therefore air from the outside kolyoba is removed, and the fine vacuum is created there. The lamp joins in network with the consecutive inductive balyolast. Mains voltage of the power supply is 240 century. Tension of ignition of 1 800 century the Puskoreguliruyushchy device obespeyochivat peak of voltage of 2,5 kV at the working current about 3 and. Time of the razgoraniye of the lamp does not exceed 2 — 3 min. Cooling time for repeated ignition — 3 min.

Do not exert impact of fluctuation of ambient temperature on light and electric parameters of the lamp of the praktiyocheska. Lamps can be operated in vertical and horizontal provisions.

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