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HPS(High Pressure Sodium) Lamp Lamp Circuit Diagram

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Author : Chris
Update time : 2019-08-31 11:30:53
The High Pressure Sodium Lamp

INTRODUCTION


The high-pressure sodium lamp was introduced in the 1960s. It is the highest-efficiency high-intensity discharge lamp and is called the third-generation illumination source. Unlike high-pressure sodium lamps, high-pressure sodium lamps are no longer monochromatic yellow, but spread over a fairly wide range of frequencies. By relaxing the line, the high-pressure sodium lamp emits golden white light, which allows for a color difference.
Because the high-pressure sodium lamp has high luminous efficiency, long life, acceptable color rendering and no attracting insects, it is not easy to discolor the object, which makes the high-pressure sodium lamp widely used in all corners of general lighting, in order to gradually It replaces the relatively high-energy fluorescent high-pressure mercury lamp. Recently developed color-improving and high-color-type high-pressure sodium lamps can replace incandescent lamps and achieve great energy savings.
For the reason of High Pressure Sodium lamp has consistently maintained its enviable position as the most efficient light source. And for the high efficient, it's very popular for people who plant. 
The construction of a typical LPS lamp is illustrated in Figure S1.



WORKING PRINCIPLE

After the start of the high pressure sodium lamp, the initial stage is a low pressure discharge of mercury vapor and helium. At this time, the working voltage of the bulb is very low, and the current is very large; as the discharge process continues, the arc temperature gradually rises, and the mercury and sodium vapor pressures are determined by the temperature of the coldest end of the discharge tube. When the temperature of the cold end of the discharge tube reaches a stable state, The discharge tends to be stable, and the luminous flux, operating voltage, operating current and power of the bulb are also in normal working condition. Under normal working conditions, the entire startup process takes about 10 minutes.

Fluctuations in the power supply voltage will cause changes in the light and electrical parameters of the bulb; if the power supply voltage rises, the operating current of the bulb will increase, the temperature of the cold end of the arc tube will increase, the vapor pressure of mercury and sodium will increase, and the operating voltage and lamp power will increase. As a result, the life of the lamp is greatly reduced; conversely, the power supply voltage is lowered, the light does not work normally, the luminous efficiency is lowered, and the light bulb may not be activated or extinguished by itself. Therefore, when the lamp is used, the fluctuation of the power supply voltage should not be too large, and it is generally required to change within the range of +6% to -8% of the rated value.

When the bulb is started, an arc is generated between the electrodes at both ends of the arc tube. Due to the high temperature of the arc, the liquid sodium-mercury gas in the tube is evaporated into mercury vapor and sodium vapor by heat, and the electrons emitted by the cathode collide with the discharge material during the movement toward the anode. The atom, which is energized to produce ionization or excitation, and then returns to the ground state from the excited state; or from the ionized state to the excited state, and then back to the ground state infinite loop, at which time the excess energy is released in the form of light radiation, Produced light. The high-pressure sodium lamp has a high vapor pressure of the discharge material, that is, the sodium atom density is high, and the collision frequency between the electron and the sodium atom is frequent, so that the resonance radiation spectrum is broadened, and other visible spectrum radiation appears, so the light color of the high-pressure sodium lamp is superior. Low pressure sodium lamp. The high pressure sodium lamp is a high intensity gas discharge bulb. Due to the negative resistance characteristic of the gas discharge bulb, if the bulb is separately connected to the grid, its working state is unstable. As the discharge process continues, it will inevitably lead to an infinite rise in the current in the circuit, and finally up to the lamp or circuit. The parts were burned by overcurrent.

VOLT-AN CHARACTERISTICS

Like other gas-discharge bulbs, high-pressure sodium lamps work in an arc-discharge state. The volt-ampere characteristic curve has a negative slope, that is, the bulb current rises and the bulb voltage drops. Under constant power conditions, in order to ensure stable operation of the lamp, a circuit component with positive resistance characteristics must be connected in series to balance the negative resistance characteristic and stabilize the operating current. This component is called a ballast or current limiter.

STRUCTURAL MATERIALS

Arc tube

The arc tube is a key component of the high pressure sodium lamp. When the arc tube is working, the high-temperature and high-pressure sodium vapor is extremely corrosive, and the general anti-sodium glass and quartz glass are not competent; and it is preferable to use the translucent polycrystalline alumina and the ceramic tube as the arc tube body. It not only has good high temperature resistance and antibacterial sodium vapor corrosion performance, but also good visible light crossing ability. In addition, single crystal alumina ceramic tubes are superior to polycrystalline alumina ceramic tubes in high temperature resistance, sodium vapor corrosion resistance and light transmittance; they are rarely used because of their high price. The arc tube is assembled with the electrode, the polycrystalline alumina ceramic tube, the cap and the solder ring, and the sodium amalgam is added into the sealing furnace to seal; and a small amount of helium is charged to improve the starting characteristics of the bulb. The electrode is spiraled with a high-purity tungsten wire, a core rod is inserted into the spiral hole, the electronic powder is impregnated, and then one end of the electrode core rod and the closed end of the manifold tube are welded together. The polycrystalline alumina ceramic tube (cap) is made by using polycrystalline alumina ceramic powder by mixing powder, spray drying, isostatic pressing, firing, high temperature sintering and cutting. The light and electrical parameters of the high pressure sodium lamp are closely related to the inner diameter and arc length of the arc tube (the distance between the two electrodes).

Wick

The wick is fixed with a metal bracket to the arc tube, the getter ring, etc., and the electrodes at both ends of the arc tube are respectively connected with the two inner guide wires on the core column. The stem is melted by a guide wire, an exhaust pipe and a horn through a high temperature flame. The expansion coefficient of the metal guide wire and the glass sealing portion should be matched to avoid that the expansion coefficients of the two sealing materials are different, causing stress on the glass at the sealing portion to burst or chronic leakage of the bulb.

Glass bulb

The glass bulb is made of high temperature hard glass. The bulb of the glass bulb and the wick is melt-sealed by a high-temperature flame, and then vacuumed or filled with an inert gas, and then the entire bulb is basically molded. Since the arc tube operates at a high temperature, the bare metal is easily oxidized and becomes brittle, and the arc tube must be placed in a vacuum or inert gas housing. This can also reduce the heat loss of the arc tube, increase the temperature of the cold end, and improve the luminous efficiency.
Lamp head
The function of the lamp head is to facilitate the connection of the lamp to the lamp holder and the circuit. The long-life bulb requires that the lamp cap and the bulb should be connected firmly, and there should be no looseness or falling off. Therefore, threaded mechanical fastening technology is generally used to prevent the natural mud from aging and falling off. The material used to make the lamp cap is generally a brass strip which maintains a small contact resistance with the lamp holder and reduces the oxide layer on the metal surface. If the bulb is used in a special environment, it can also be coated with a chrome or nickel layer on the surface of the brass base. Its specifications and models are: E27, E40 two.

Air getter
After vacuuming in the glass bulb, the metal parts can still be oxidized, which affects the stable operation of the bulb; therefore, placing a proper amount of getter in the bulb can increase the vacuum inside the bulb to a high vacuum state. High-pressure sodium lamps generally use a helium getter, which is placed in a metal ring and then fixed in a position where the getter does not affect the light output after evapotranspiration. After the bulb is vacuumed, the metal ring is heated by high frequency induction, so that the niobium titanium alloy in the ring is heated and then evaporated, and the residual harmful gas is absorbed during the evapotranspiration process, and a black mirror surface is formed on the neck of the glass bulb. It must be pointed out that the location of the getter is very important, and the black mirror does not hinder the light output; if some or all of the black mirror is grayish white during use, it indicates that the light bulb has leaked and cannot be used any more. It must be replaced. light bulb.

Mercury is liquid in the normal state and has a silver-white specular gloss. Adding mercury to the arc tube can increase the working voltage of the lamp, reduce the working current, reduce the volume of the ballast, improve the power factor of the grid, increase the arc temperature, and increase the radiated power.

The sodium element is a silvery white metal, also known as metallic sodium. Its physical and chemical properties are soft and light, soluble in mercury vapor. The sodium spectrum is characterized by a resonant radiation line width, a reddish zone, and a high total radiant power; the light color and luminous efficiency of the high pressure sodium lamp are related to the sodium vapor pressure. The industrially produced high-pressure sodium lamps are all added to the bulb using sodium amalgam, which simplifies the production process and greatly improves the consistency of the bulb parameters.

Helium is a rare gas that acts in the bulb to help start and lower the startup voltage. The level of pressure will also affect the light bulb's illumination.

Ballast
In the working circuit of the high-pressure sodium lamp, the ballast used with the bulb has two types: an inductive ballast and an electronic ballast.

Electronic ballast

The inductive ballast is made of an inductive coil and a silicon steel sheet loop, and a small gap is reserved to keep the magnetic field in an unsaturated state, thereby stabilizing the current. As the name suggests, the electronic ballast is a cathode device with electronic components. It is also a product that implements lighting and energy saving. It has the characteristics of low power consumption, small size, light weight, high power factor, instant start of the bulb, etc. Gas discharge lamps (compact energy-saving lamps) are widely used, and in high-power gas discharge lamps, the difficulty is large.
The ballast is an important accessory for high-pressure sodium lamps. Its performance and quality directly affect the life, luminous efficiency and self-extinguishing of high-pressure sodium lamps. High-pressure sodium lamp ballast generally requires low power loss, easy installation and firmness, and good waterproofing.
Inductive ballast
Anti-corrosion and safety performance, can work continuously for more than 12 hours at ambient temperature -40 ~ +45 °C. The ballast power is measured at the rated voltage as compared to the lamp power measured with the specified reference ballast, and the deviation should be within ± 7.5%. It must be reiterated: High-pressure sodium lamps of different specifications must be equipped with ballasts of corresponding specifications. Bulbs and ballasts cannot be used arbitrarily. Especially when low-power bulbs are equipped with high-power ballasts, the operating current of the bulbs is too large and the use is shortened. Lifespan can even burn the bulb. During the entire life of the coal bubble, the voltage-power characteristic of the ballast must vary within the specified bulb voltage and power limits.
electrical system
In the working circuit of the high-pressure sodium lamp, in addition to the bulb, the corresponding working circuit, such as the bulb + ballast or the lamp + ballast + trigger working circuit, must be selected according to the internal trigger high-pressure sodium lamp or the externally-triggered high-pressure sodium lamp. In order to meet the requirements of normal operation of high pressure sodium lamps.

High pressure sodium lamp working circuit system

main feature
When the high-pressure sodium lamp is used, it emits golden white light, which has the advantages of high luminous efficiency, low power consumption, long life, strong fogging ability and no attracting insects. Widely used in roads, highways, airports, terminals, 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 in stadiums, exhibition halls, casinos, department stores and hotels.
The incandescent bulb emits warm light when it is working, and its color rendering is excellent (color rendering index Ra=100). It has been widely used as an illumination source for a long time since its birth. Although the use of high pressure sodium lamps has many advantages, the color rendering is poor (Ra = 30). In order to maintain the long life of the high-pressure sodium lamp, high luminous efficiency and warm tone atmosphere; in the improvement of color rendering, people have worked tirelessly to develop high-color high-pressure sodium lamps (also known as white high-pressure sodium lamps) that meet the above requirements.
White light high pressure sodium lamp
The high color rendering high-pressure sodium lamp is based on the high-pressure sodium lamp, which improves the color rendering by increasing the sodium vapor pressure and increasing the diameter of the arc tube. At the same time, a layer of bismuth foil is wrapped on both ends of the arc tube to improve the temperature of the cold end. In addition, the helium gas pressure in the arc tube is increased to increase the temperature of the arc center portion, and the temperature of the remaining discharge portion is lower. The color rendering property is improved by changing the arc temperature distribution, and the color rendering index is increased to Ra=70. ~ 80, luminous efficiency of up to 80 lm / w or more, can broaden the application field, to replace the incandescent bulb with high color rendering high pressure sodium becomes a reality.

THE KIND
1) Ordinary high-pressure sodium lamp This type of lamp uses the atmosphere as the starting gas, and the vapor pressure of the sodium in the discharge tube ensures the maximum luminous efficiency of the lamp. Its characteristics are high light efficiency and long life, but the light color is poor, and the general color rendering index is only 15-30. Therefore, it can only be used for lighting in roads, factories, etc.

2) The high-pressure sodium lamp that directly replaces the fluorescent high-pressure mercury lamp is produced for the promotion of high-pressure sodium lamp. It can be directly used in fluorescent high-pressure mercury lamp ballasts and lamp devices of similar specifications.

3) The comfortable high-pressure sodium lamp is used to expand the application of high-pressure sodium lamp in indoor and outdoor lighting, and its color temperature and color rendering are improved, so that the high-pressure sodium lamp is suitable for use in residential areas, industrial areas, retail commercial areas and public places.

4) High-efficiency high-pressure sodium lamp is filled with high-pressure helium gas in the lamp tube, which makes the lamp have high luminous efficiency, and also improves the color rendering index. It can be used as an energy-saving light source for indoor lighting, especially suitable for Lighting in factory lighting and sports venues.

5) High color rendering high pressure sodium lamp In order to meet the high color rendering requirements, people have successfully developed a high color rendering high pressure sodium lamp, also known as white light high pressure sodium lamp. The improved lamp has a general color rendering index. Another important feature is that the color temperature rises above and is very close to incandescent lamps. Therefore, it has a warm white hue and high color rendering, which has a great effect on beautifying the city and beautifying the environment. This kind of lamp can be used for commercial lighting and lighting of high-end goods such as gold jewelry, jewelry, precious leather goods, etc., and the energy saving effect is very remarkable.

DIFFERENCE

Low pressure sodium lamp

The low-pressure sodium lamp is a low-pressure sodium vapor discharge tube. The inner tube is blown with special anti-sodium glass. After ignition, it can radiate 5890A and 5896A sodium lines, which can be used as optical instruments such as polarimeter, refractometer and polarimeter. Monochromatic light source.

HPS

When the high-pressure sodium lamp is used, it emits golden white light, which has the advantages of high luminous efficiency, low power consumption, long life, strong fogging ability and no attracting insects. Widely used in roads, highways, airports, terminals, 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 in stadiums, exhibition halls, casinos, department stores and hotels.


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