How LED High Bay Lights Withstand High Temperature Industrial Environment

LED high bay lights are widely used in industrial environment due to their high power, high efficiency, and low energy consumption. Environment of iron and steel manufacturing, pulp and paper mils, and so many industrial plants are harsh and heavy. Harsh industrial environments such as high temperature, heavy dust, and vibrations, are serious risks of stable lighting performance. However, there are LED high bay lights that claimed to work well in high temperature industrial environment. Some of them can withstand up to 70 °C ambient temperature. As we all know, extreme temperature will cause lumen depreciation and reduced light output. How those LED high bay lights withstand high temperature in industrial environment?

Effects of high temperature on lighting

In short, high temperature will damage lighting performance. As known, LEDs generate less heat than conventional light sources during operation. But higher ambient temperature results higher junction temperature. Furthermore, LED fixtures are made of more than just LEDs. Drivers and other electronics components are significantly sensitive to high temperature. A long term high junction temperature leads to degradation of electronic elements, accelerating lumen depreciation and causing possible failure. As a result, lifespans and lighting performance of LED fixtures are shortened. High temperature also increases the risk of fire, threatening the lives.

General temperature classifications of fixtures are 25 °C, 40 °C, 55 °C, and 65 °C. LED fixtures function well in 25 °C ambient temperature, but LED currents drop sharply when ambient temperature over 55 °C. In poor dissipation condition, junction temperature is higher than ambient temperature. The excess high temperature reduces the lighting output. Temperature of the mounted locations often exceeds the floor level. Therefore, to ensure stable lighting performance and safety, rated temperature of the fixture must be higher than the ambient temperature.

Ways to withstand high temperature industrial environment

Since high temperature can cause the decay of lighting performance and there are requirements for LED high bay lights that are able to withstand high temperature in industrial environment, it is critical to optimum lighting performance in high temperature industrial environment. But we should note that is the junction temperature but not the ambient temperature actually affects the LED fixtures. Therefore, temperature control of fixtures themselves is the leading issue for maintaining lighting performance in high temperature industrial environment. Heat dissipates through conduction, convection and radiation. To achieve optimized temperature control, one of the key points is to accelerate heat dissipation, while the other is to ensure the heat resistance of the fixture components.

• Heat sink

Heat sink is one of the most effective ways to help high bay lights dissipate heat. Heat sink is a structure to conduct the heat away from LEDs to the air, reducing the heat accumulation on junctions and LEDs. To improve heat dissipation efficiency, heat sink is constructed in large surface areas. Fins and channels are the common structures to enlarge surface areas and provide sufficient air flow. Except for the structures, material with greater thermal conductivity is also beneficial for heat dissipation. Aluminum is a typical heat sink material that is used for industrial environment. The size of the heat sink is determined by the generated heat ambient temperature. Larger heat sink is need in higher temperature environment. Robust heat sink reduces lumen depreciation and then extends working life in high temperature industrial environment. That is the reason for why most high bay lights shaped like UFO.

• Special housing

Housing system is essential for heat resistance and thermal control of high bay lights. It plays an important role in protecting LEDs from high ambient temperature and allowing higher thermal conductivity. Aluminum is selected as the common housing material due to its excellent performance in heat dissipation and easier manufactured process. There are various manufactured processes for aluminum housing. Extrusion, forging, casting, and stamping are the common and cost-effective aluminum manufacturing methods. Higher aluminum purity refers to better thermal conductivity but also higher cost. Surface finish of the housing is a practical way to resist corrosion and increase emissivity. A housing painted with acrylic power cost finishes has greater thermal radiation than unpainted one. Most housing of high bay lights are manufactured with vertical cooling ribs. These vertical ribs work well in preventing dust deposits, reducing  obstacles of thermal radiation from LEDs to the air.

• Isolate the driver

LED drivers, also called LED power supply, supply and regulate the power to LEDs. Drivers are sensitive to high temperature. Excessive operating temperature will influence the reliability and shorten the lifespan of driver. Failures of fixtures are often caused because of the poor performance of driver. Moreover, drivers generate heat when it is supplying power to LEDs. Drivers cause strong thermal stress to LEDs and result lumen output reduction. Actions should be taken to pull the heat away from drivers as well as LEDs to ambient. Aluminum enclosures are used to improve heat dissipation and facilitate thermal load to the drivers. Isolating driver from luminaires reduces heat accumulation and accelerates heat dissipation, which is ideal for high temperature applications. Separating the drivers also contributes to relieve heat stress on LEDs.

HB45 Sun-chariot are typically designed for high temperature industrial environment up to 70 °C. Cold forging heat sink provides excellent thermal conductivity and larger heat dissipation area for optimum heat dissipation. Back cover plate and vertical cooling ribs prevent dust deposits. HB45 is safe to operate in high temperature industrial environment without compensating powerful lumen output.