Low pressure sodium lamp is an electric light source that uses low pressure sodium vapor to discharge light, and its glass shell is coated with infrared rayReflective film, Yesluminous attenuationSmaller andluminous efficiencyHighest electric light source.The low-pressure sodium lamp emits a monochromatic yellow light, which is used in places where there is no requirement for light color, but its "fog permeability" is very excellent, especially suitable for highway, traffic roads, municipal roads, parks, and courtyard lighting, which can make people see clearlychromatic aberrationA relatively small object.Low pressure sodium lamp is also a substituteHigh pressure mercury lampbrownoutAs a kind of high-efficiency lamp, its application places are also expanding.
Low pressure sodium lamp has high visual luminous efficiency, but due toSpectral distributionToo narrow,Chromogenic propertyrange, so it is not suitable forCommercial lightingField, mainly suitable forroad lighting , especially in Europe, such as the United Kingdom, the Netherlands, France and Germany.In terms of the overall performance of the light source, the best configuration light source for solar energy is the low-pressure sodium lamp andLEDThere are also quite a few cases of lamps in China. Long life, high energy saving and green environmental protection are the characteristics of such energy-saving light sources.
Product selection
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WhenGas discharge lampWhen the instantaneous fluctuation of the power supply voltage drops greatly, the lamp will automatically extinguish, which is especially important for some light sources that cannot be restarted immediately after extinction.Certainsafety factor, make the power grid instantaneousVoltage variationNot lower than a certain allowable value.Gas discharge lamps are mostly usedmagnetic ballast , power factor is less than 1.2) When gas discharge lamps are used for lighting in large areasEquipment utilizationCompensation shall be considered to improve the power factor. Generally, centralized compensation method is convenient.When selecting conductor section and lighting transformer capacity, it is not only necessary to calculate the consumption of light sourceelectric powerAnd should be includedBallastLoss power.Select according to the characteristics of light source: such asHigh pressure gas discharge lampThe startup time and restart time of are both long, so it is not suitable for important places (such as main control room of power plant, banquet hall, etc.).Emergency lighting is also not suitable.
advantage
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No color difference
The near monochromatic radiation emitted by the low pressure sodium lamp does not produce chromatic aberration in human eyes, so the visual resolution is better than that of continuous or multi line spectral radiation, which improves the contrast.From the perspective of traffic safety, this factor is very meaningful for places requiring high visibility.For example, good visibility is required for motorways, road intersections, viaducts, road entrances and tunnels, etc.In these places, the color rendering of the light source is relatively less important, and it is more appropriate to use low pressure sodium lamp for lighting.Low pressure sodium lamps are also valuable in places where lighting is mainly considered for safety alert purposes.Low pressure sodium lamps can also be used for lighting in these places.For example, residential areas, offices, banks, garages, factory and hospital sites, coal yards and other places that need a limited number of light spots to use their characteristic light colors as traffic guidance.
Low pressure sodium lamp has extremely high luminous efficiency
Luminescence efficiencyPhotoefficiency。It is generated by electric light sourceLuminous fluxAnd itPower consumptionThe unit isLumen/Watt (lm/W) is the most important technical parameter to evaluate the power efficiency of electric light source.Luminous flux refers toray radiationThe quantity is expressed in lumens.Light source unitelectric powerThe greater the luminous flux emitted, the higher the efficiency of electric energy conversion to light energy, that is, the higher the luminous efficiency.
Other advantages
Low pressure sodium lamp has other advantages. For example, the shape of low pressure sodium lamp is long and its brightness is relatively low. Therefore, there is no dazzling problem. In addition, the operating temperature of low pressure sodium lamp is low, and the optical system of the lamp will not be damaged prematurely due to the deterioration of environmental gases.
principle
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Low pressure sodium lamp
Use low pressure sodium vapor (workingVapor pressureNot more than several Pa) dischargevisible lightElectric light source of.Low pressure sodium lamp was invented in 1930.In 1932, Philips of the Netherlands commercialized the low pressure sodium lamp for the first time.After continuous improvement, the low pressure sodium lampluminous efficiencyIt has reached 450lm/W, becoming the light source with the highest luminous efficiency among various electro-optic sources.Low pressure sodium lamp principle: based on low pressure sodium -- rare gasDischarge principleAnd the luminous electric light source.Since sodium is a solid at room temperature, sodium is used onlyGas discharge lampHard to start.Fill the glass tube of the lamp with argonNeon mixtureThat is, after Penning gas, the lamp first presents the characteristic red light of neon when discharging, and generates heat toThe discharge tubeThe sodium begins to evaporate when the temperature rises;NatrogenicIonization potentialandExcitation potentialIt is lower than neon and argon, and the discharge quickly turns into sodium vapor and emitsvisible light。Low voltage sodium discharge radiation is concentrated on the two double D spectral lines of 589.0nm and 589.6nm, which are very close to the highest value (555nm) of the spectral light curve, so itsluminous efficiencyExtremely high.
Low pressure sodium lamp structure
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There are two types: straight tube and U-shaped.The straight tubular low pressure sodium lamp is similar toFluorescent lamp。It has an arc discharge with two end leadsLight-emitting tubeThe tube is filled with sodium and argon neon mixture, and two ends are sealed with an electrode.The discharge tube is sealed in a vacuum outer tube, and two ends of the outer tube are respectively equipped with a double pin lamp cap.U-shaped low pressure sodium lamp adopts a discharge tube with thin and long tube diameter and bends it into a U-shaped shape to reduce the volume of the lamp, and enable the two tube ends of the bend to heat each other to reduce heat loss.The discharge tubeThe glass shell is resistant to sodium vaporSodium resistant glassmake.In order to reduce the heat loss caused by conduction and convection, the discharge tube is placed in the vacuum cylindrical outer glass shell, and the inner wall of the glass shell is coated with a layer that can penetratevisible lightAnd can reflect infrared ray, so as to reduce thethermal radiationLoss, improve the luminous efficiency of low pressure sodium lamp.This transparent reflective infrared coatingIndium oxideMost films.The outer glass shell of the lamp is also provided with a bracket to support the discharge tube.Specifications and features: power is 18W, 26W, 35W, 36W, 55W, 66W, 90W, 135W and other specifications.
Energy saving light source
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Low pressure sodium lamp
Low pressure sodium lamp is a kind of low pressure sodium vaporThe discharge tubeIt is blown with special sodium resistant glass, and can emit 5890A and 5896A sodium spectral lines after ignition, which can be used asPolarimeter、Refractometer、PolarimeterMonochromatic light source in optical instruments such as.A low-voltage sodium lamp in the field of electric light source, comprisinginert gasandMetallic sodiumThe discharge tube is set athigh vacuumThe discharge tube is fixed with the outer glass shell through the support frame, and the two poles of the discharge tube are provided with electrodesThe discharge tubeThe utility model comprises a sodium resistant sheathed glass tube, which is U-shaped;Sodium resistant sheathed glass tube is made ofSilicate glassAnd the sodium barium resistant glass layer of the inner layer.Compared with modern technology, the U-shaped discharge tube has a compact structure, which makes the outer glass shell small and the heat dissipation surface smallertemperature riseThe utility model is fast and has good light convergence, which can make the discharge tube reach the working temperature of 260 ℃ quickly. The utility model can be widely used in roads, tunnels, warehouses, docks and other lighting places in different temperature areas, with high light efficiency and strong light penetration.
The service life of low pressure sodium lampNumber of ignition pointsHowever, it is generally 19000 hours.luminous attenuationIt is smaller than other light sources and can reach 80~85% of the initial luminous flux at the end of life.Due to discharge of low-voltage sodium lampLight-emitting tubeLong, the migration of sodium in the ignition point has a certain impact on the performance and life of the lamp, so the ignition point direction should be specified to prevent sodium migration (generally, the allowable horizontal deflection angle is within ± 20%, and the allowable deflection angle of low-power low-pressure sodium lamp can be larger).Low pressure sodium lamp radiates monochromatic yellow light,Chromogenic propertyGenerally, applicable to those with high illuminance requirements but no requirements for color renderingLighting placeEnergy saving light source: low pressure sodium lamp is a kind ofluminous efficiencyHigh energy saving light source.The development and application of low pressure sodium lamp is of great significance to countries and regions with power shortage.[1]
Operating characteristics
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Temperature rise characteristics
Low pressure sodium lamp works by discharging low pressure sodium vapor.At the beginning after the lamp is started, the discharge only occurs in the rare gas neon, which can be seen from the neon red characteristic radiation emitted during the discharge.Noble gasThe heat generated by the discharge causes the solid sodium in the discharge tube to melt and partially vaporize, so sodium atoms participate in the discharge.Due to the low excitation potential and ionization potential of sodium, the radiation emitted by sodium is far more than that of neon.When the discharge tube is hot enough, the color of light radiation emitted by the lamp will become yellow showing the characteristics of sodium.
Photoelectric characteristic
It can be seen from the experiment that with the change of supply voltage, the changes of lamp current and lamp voltage tend to cancel each other, and the result is that the lumen output of lamp power almost remains unchanged in a wide range to a certain extent.
Restart characteristics after voltage interruption
Unlike high voltage discharge lamps, like fluorescent lamps, hot low pressure sodium lamps in operation will immediately emit full luminous flux or reduced luminous flux corresponding to cooling time after a short interruption of current.This feature makes low pressure sodium lamp suitable for street lighting.If the interruption time is very short, the lamp can immediately send out nearly all luminous flux after being ignited again.For the high pressure discharge lamp, after the current is interrupted, it can be ignited again after the discharge tube is fully cooled.This is a defect of high-pressure discharge lamps used for lighting.[1]
type
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At present, there are two types of low pressure sodium lamps on the market, one is the conventional low pressure sodium lamp, and the other is the economical low pressure sodium lamp.Generally speaking, the difference between the two types of lamps is that economic lamps are more efficient and consume less power.But this does not mean that the light flux of economical low pressure sodium lamp is high.That is to say, in the light fixtures requiring a certain lighting level, the more economical low pressure sodium lamp cannot simply replace the conventional low pressure sodium lamp.Economy lamps have better thermal insulation performance than conventional lamps.In order to produce the same light output, the economy lamp only needs to input lower electrical power, but the total luminous flux of the lamp is lower.Economical low pressure sodium lamps also work well in the working circuit of conventional low pressure sodium lamps. However, when they work in the choke type ballast or self failureFlux leakage transformerIn the circuit, the advantage of low energy consumption is not obvious.[1]
difference
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Low pressure sodium lamp
Low pressure sodium lamp is a kind of low pressure sodium vaporThe discharge tubeThe inner pipe is blown with special sodium resistant glass, and can emit 5890A and 5896A sodium spectral lines after ignition, which can be used asPolarimeter、Refractometer、PolarimeterMonochrome in optical instrumentslightSource.
High pressure sodium lamp
High pressure sodium lampIt emits golden white light when used, and hasluminous efficiencyIt has the advantages of high power consumption, long service life, strong fog penetration and no insect trapping.Widely used in roads, highways, airports, docks, docks, stations, squares, street intersections, industrial and mining enterprises, parks, courtyard lighting and plant cultivation.High color rendering high-pressure sodium lamps are mainly used for lighting in stadiums, exhibition halls, entertainment centers, department stores, hotels and other places.
