Introduction of high pressure gas discharge lamps


The high-pressure sodium lamp emits golden white light […]

The high-pressure sodium lamp emits golden white light when used, and has the advantages of high luminous efficiency, low power consumption, long life, strong fog-passing 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.
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 sodium amalgam in the tube is evaporated by heat into mercury vapor and sodium vapor. The electricity emitted by the cathode moves into the anode, and the impact discharge material has An atom, which obtains energy to generate ionization excitation, and then returns from an excited state to a stable state; or from an ionized state to an excited state, and then returns to the infinite cycle of the base level, and excess energy is released in the form of optical radiation, thereby generating 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 to the light or the circuit. Zero, the parts were burned by overcurrent.
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. Resistors, capacitors, and electrical susceptors all have a finite current effect. Resistive ballasts are small in size and cheap in price. It is difficult to start up with high-pressure sodium lamps. When working, the resistors generate high heat. It requires a large heat dissipation space and consumes a lot of power, which will make the total lighting efficiency of the circuit. decline. It is generally used in DC circuits, and the use of lights in a hundred AC circuits has a noticeable flicker. Although the capacitive ballast does not consume much power like the resistive ballast, the temperature rise is low. When the power frequency is low, when the capacitor is charged, the pulse peak current will be generated, causing great damage to the electrode and the light flashes. Affects the life of the lamp; working in a high-frequency circuit, the voltage fluctuation can reach an ideal state, becoming an ideal ballast. Inductive ballast has low loss, stable impedance, small deviation of resistin and long service life. The stability of the bulb is better than that of the resistive ballast. The ballasts currently used with the high-pressure sodium lamp are inductive ballasts. . Its shortcomings are heavier than benzene and the price is high. In addition, electronic ballasts have begun to appear, and they are currently expensive, and the reliability cannot be matched with high-pressure sodium lamps. In general, they are rarely used except for special occasions. Therefore, the high pressure sodium lamp must be used in series with the ballast corresponding to the lamp size. The lighting circuit of the high-pressure sodium lamp is a non-linear circuit with a low power factor, so the compensation capacitor is considered on the network to increase the power factor of the network.

Introduction of high pressure gas discharge lamps