High Power LED Projectors
A high-power LED floodlight is a weatherproof lighting system, usually designed to illuminate a scene or object with a much greater brightness than its surroundings. The high-brightness luminaire offers an intense light output with an easily changeable and controllable beam pattern to illuminate a selected area or object to ensure safety and visual comfort. Projectors can be categorized into two broad types, area and direction, as a result of controlling the distribution and intensity of the beam to facilitate shaping the luminaire output. High power LED floodlights are used in lighting applications that require light intensity distributions to illuminate large open spaces such as parking lots, outdoor stadiums, indoor arenas and warehouses. Directional floodlights are used for architectural wall and facade lighting to visually highlight a particular architectural or structural feature.
HID Lighting Disadvantages
Metal halide (MH), mercury vapor (HgV), high pressure sodium (HPS) and low pressure sodium (LPS) lighting systems were used frequently in industrial and outdoor lighting applications requiring high intensity lighting. While high-voltage (e.g. 1000 watts or more) HID projectors produced a significant amount of light, their disadvantage was that they limited their application to outdoor lighting. For example, HPS lamps have a wider light spectrum but lower efficiency (amount of light produced versus the amount of light given). Although metal halide lamp is widely used in sports and other large area lighting applications, it still has several disadvantages. HID lamps require a long warm-up/start-up time of several minutes before providing usable light. A metal halide lamp produces light by passing a quartz or ceramic arc tube through a mixture of gaseous vaporized mercury and metal halide. The cold metal halide lamp cannot produce its full light capacity immediately and it takes about 5 minutes for the electric arc between the electrodes to radiate the visible light to full brightness. A warm reboot is more of a concern than a prolonged startup. Since the high pressure inside the arc tube can reach 440 psi (30 bar), it can take up to 20 minutes to restart the arc if power is lost. In addition to having a limited life of approximately 3,000 hours for high watt applications and poor lumen maintenance, metal halide lamps contain significant amounts of mercury and are prone to an explosion risk.
High Power LED Projector Lighting
Many of these shortcomings in HID projectors have resulted in the need for a better lighting system for applications that require high power lighting. The increased efficiency, long life and other advantages of LEDs (light emitting diodes) have enabled them to replace many industrial and outdoor lighting applications that were previously the uses of HID lights. Compared to traditional light sources High power LED floodlights have the following features that make them suitable for many lighting applications.
It plays a big role in economics, industrial and commercial lighting applications. Energy consumption, resource savings, maintenance and long-term sustainability are all important factors to consider for any lighting installation. A high-output lighting system consumes a significant amount of electrical energy to produce light for high-intensity large-area lighting. While the luminous efficiency of HID projectors (Watts per lumen, lm/W) is comparable to their LED counterparts - HPS lamps have an efficacy of 75 to 130 lm/W, LPS lamps have a high efficiency of 130 to 185 lm/W and MH lamps have between 70 and 115 lm/W has an efficiency average. High-power LED luminaires, on the other hand, use more efficient and durable semiconductors and can have an L70 life of up to 50,000 hours. L70 life is defined by the Illuminating Engineering Society Standard LM-80-08 and defines the expected number of operating hours until light output drops to 70% of baseline levels. MH lamps (and most HID lamps) feature lamp lumen depreciation (LLD). They have an initial light output at rated power (luminous efficiency), but then lumen wear occurs most rapidly in the first 100-200 operating hours (eg 20% attrition). During its working life, the lamp usually gradually loses its lumen output from the LLD. For example, a typical 1500W MH projector may lose approximately 50% of its initial light output over its cumulative operating life of 3000 hours. This means that LED lights have a much longer lifespan than MH lamps. Today's white LEDs have an average luminous efficacy between 120 and 150 lm/W. In addition, it is practically possible to increase the luminous efficiency of high-power LEDs up to 200 lm/W with further improvements in base material and design. The economic benefits of LED lighting are obvious given its increased efficiency, extended lifetime, negligible maintenance investment and significantly reduced lamp cost leading to shorter payback time.
Better Light Quality
Solid state lighting is well suited for high color rendering lighting and results in a high color rendering index (CRI) value in the 70-95 range. CRI is a measurement of the color reproduction quality of artificial lighting products. Higher CRI means better quality because artificial light is more natural and more likely to detect color separation (i.e. detect subtle difference in hue). Metal halide bulbs typically have a CRI of about 65, which is insufficient to produce a colored surface. In some lighting applications, such as sports lighting, high CRI is highly desirable for televised sporting events. The excellent color rendering capability of LED lighting allows spectators to see the event on the field in bright and vibrant colours, allowing objects to be distinguished even by subtle hue differences. LED lighting is inherently versatile. Unlike HID bulbs, which emit light in all directions, LEDs produce directional light with an optical efficiency of 80% to 90%. Typical intensity losses for metal halide lamps range from 40% to 60% of the light produced. High optical loss will tend to cause unwanted light pollution in the field such as glare, scattered light, uplight and halo light. LED lighting, on the other hand, produces a beam pattern that can be more easily changed and controlled to meet the light quantity and uniformity characteristics and is therefore useful and desirable in the lighting industry.
Beyond Operating Cost and Light Quality
LEDs are redefining high power lighting technology. In addition to the aforementioned benefits such as longer lifespan, lower operating costs and better light quality, LED lighting offers many other advantages over conventional light sources. LED is a light source equipped with instant-on technology that will eliminate the initial waiting time for HID lamps to start and restart after shutdown. The solid-state nature of the LED provides greater resistance to mechanical shocks or vibrations, thus significantly increasing its durability. LED lights are fully dimmable with no color change. By the process of changing the brightness or brightness of an LED lamp, certain ir light level can be obtained. Also, they are metal halide light bulbs that produce significant amounts of short-wave ultraviolet light (UV) that can be dangerous to humans. In contrast, an LED luminaire emits almost no ultraviolet light or infrared radiation. LEDs do not contain mercury or any other hazardous substances and are therefore environmentally friendly.
Optical assembly design compels every projector luminaire designer to meet customer's demands and meet the parameters of different optical solutions. The primary optic is included in the LED package and the secondary optics are part of the projector fixture and are designed to shape the radiation pattern or beam pattern, maximizing efficiency and application range. Secondary optics provide unique optical combination possibilities to vary the LED output beam of the projectors so that the output beam meets the desired photometric specification efficiently. LED secondary optics include reflectors, lenses, total internal reflection (TIR) lenses, and diffusers. The lens has excellent light-gathering ability to control the dispersion of light rays at a small angle. The reflector has the advantage of reorienting the illuminance and converging the rays at a wide angle. A TIR lens is a lens and reflector combination that uses the principle of total reflection optics to collect and process light. For high voltage applications, PMMA (acrylic) or PC (polycarbonate) lens is recommended due to its high mechanical strength, excellent optical properties, good thermal stability, high thermal conductivity and low moisture and water absorption capacity. In high power projector lighting, lenses and TIR lenses are often used for better uniformity and higher optical efficiency (at least 90% for most applications). However, in some applications it makes sense to use a reflector design to achieve a designed beam pattern and minimize spill light and glare (eg sports lighting).
High power LED floodlight optics are available in different light distributions (asymmetrical, symmetrical and antisymmetrical) with different light distributions to suit floodlighting, spot lighting, road and area lighting applications.
Spot - Spot distribution can be applied to installations where precise lighting and light control is required for small, confined spaces over long distances. Typical applications include accent lighting, tall façade lighting and flagpoles.
Narrow - The narrow beam provides a concentrated distribution for applications where a tight symmetrical distribution is highly desired. Typically used to highlight the landscape, monuments, shop windows and building facades.
Medium - Designed for high-intensity floodlight or area lighting applications that require a larger uniform pattern in a defined coverage area.
Wide - Wide-beam floodlight is designed for general floodlighting applications where wide, even illumination over a large area is required. Typical applications include pole-mounted high-power floodlighting and large area lighting, and floor-mounted signage and façade lighting.
Horizontal - Projects a wide horizontal beam with a narrow vertical concentration. This distribution model is ideal for applications that require vertical cutting.
Vertical - Ideal for applications that require beam spread, horizontal cutting but deep distribution vertically.
The wiring of high power LED floodlights includes one or more LED drivers designed to operate LEDs under wide temperature and electrical ranges to ensure reliability for the most demanding applications. The driver is designed to accept a universal input voltage. The system power factor is usually greater than 0.9 at full load. Total harmonic distortion or THD should not exceed 20% (less than 10% THD is exceptionally good). The drive is thermally protected from excessive temperature. Output overvoltage and overcurrent circuitry protect against transient peak currents, transient voltage spikes and dips that can occur in electrical systems, which would otherwise cause burnout or premature LED failure. The drive components are housed in a waterproof, flameproof plastic enclosure with protection level IP66/67.
The implementation of controls in lighting systems with high-power LED projectors provides many benefits such as energy savings, reduction of light pollution, extension of luminaire life and compliance with energy codes. LED drivers are usually equipped with dimming circuitry for 0/1-10V dimming, DALI digital dimming or PWM dimming to allow adjustment of lighting levels. LED floodlights can also be controlled by motion sensors and are configured to light from low power to high or turn on/off when motion is detected. A photocell can be installed to provide dusk-to-dawn lighting. Abrasive management system or addressable smart controls offer the greatest flexibility and provide versatile communication channels for networked control.