The various types of electric light sources used in lighting engineering can be divided into two categories according to their working principles: one is thermal radiation light sources, such as incandescent lamps, halogen lamps, etc; Another type is gas discharge light sources, such as fluorescent lamps, high-pressure mercury lamps, high-pressure sodium lamps, etc.
(1) Incandescent lamps: Incandescent lamps have the characteristics of simple construction, easy use, instant ignition, no flicker phenomenon, good color rendering performance, and low price. However, they have low luminous efficiency, short lifespan, and low seismic performance.
(2) Halogen lamp: The spectral energy distribution of halogen lamps is similar to that of incandescent lamps and is also continuous. Tungsten halogen lamps have the characteristics of small size, high power, instant ignition, adjustable brightness, no flicker effect, good color rendering, and high luminous efficiency.
(3) Fluorescent lamps: Fluorescent lamps have the characteristics of high luminous efficiency, long lifespan, low surface temperature, good color rendering, and uniform light distribution. The main disadvantages of fluorescent lamps are difficulty in starting at low temperatures, significantly reduced light efficiency, and low power factor of fluorescent lamps.
(4) High pressure mercury lamp: High pressure mercury lamps have the characteristics of high light efficiency, shock resistance, heat resistance, and long service life. But the disadvantage is that it cannot ignite instantly, has a long start-up time, and has poor color rendering. The voltage offset has a small impact on the light output, but the voltage fluctuation is too large. If the voltage suddenly drop-s by more than 50%, it can cause the light to automatically turn off, and it will take 5-10 seconds to restart. Therefore, the voltage change should not exceed 5%.
(5) High pressure sodium lamp: High luminous efficiency, about twice that of fluorescent high-pressure mercury lamps, and long lifespan, but poor color rendering, with an average color rendering index of 21. The variation of power supply voltage has a significant impact on the photoelectric parameters of high-pressure sodium lamps. When the voltage drop-s below 5%, it can cause the lamp to turn off on its own, and it takes about 10-15 seconds to restart. The change in ambient temperature has no significant impact on high-pressure sodium lamps, which can operate within the range of -40 ° C to 100 ° C. High pressure sodium lamps also have low ultraviolet radiation, good fog transmission performance, shock resistance, and are suitable for large space lighting with high illumination requirements.
(6) Metal halide lamps: Compared with high-pressure mercury lamps, they have higher luminous efficiency (70-100 lm/W), good color rendering, an average color rendering index of 60-90, weaker ultraviolet radiation, but lower lifespan than high-pressure mercury lamps.
This type of lamp requires a ballast when in use, and 1000W sodium, thallium, and indium lamps also require a trigger to start. Changes in power supply voltage not only affect light efficiency, tube voltage, and light color, but also cause the lights to turn off when the voltage changes too much. Therefore, the power supply voltage should not exceed ± 5%.
(7) Xenon lamp: Its light color is very good. Its power is relatively high, the light color is close to sunlight, and it has the characteristics of low temperature resistance, high temperature resistance, shock resistance, stable operation, and high power. Xenon lamps emit strong ultraviolet radiation and generally do not require ballasts. However, in order to improve the stability of the arc and the starting performance, ballasts are still used for low-power tubular xenon lamps. Xenon lamps need to be started by triggers, and the triggering time should not exceed 10 seconds each time. The working temperature of the lamp is high, so the lamp holder and the lead wire of the lamp head should be resistant to high temperatures.