The research of the heating of LEDs of a compact luminaire for a local lighting system

The compact LED luminaire is one of the main elements of the dynamic local lighting system for poultry cages, which allows changing the level of illumination on the normalized surface and the color temperature of optical radiation. An important task in the design of LED luminaires is to determine the operating temperature of the light-emitting crystal. The degree of reduction of the luminous flux during operation, the service life and reliability of the luminaire depend on this parameter. In the developed luminaire, two SAMSUNG LM561B Plus LEDs with a correlated color temperature of 2700 K and 5700 K, operating at a current of 100 mA, are used to create illumination up to 25 lux on the bottom of the feeder. The purpose of the research was to determine the heating temperature of the LEDs of a compact luminaire of a local lighting system on three different types of printed circuit boards for LEDs. In the work, an indirect method for determining the temperature of a light-emitting crystal, based on the temperature change in the forward voltage drop across the LED, is applied. The research was carried out on a laboratory installation consisting of the luminaire with the investigated printed circuit board for LEDs, a suspension, a high-precision parametric current stabilizer, a power supply, a personal computer with an analog-to-digital converter board LA70M4 and specialized software. The heating temperature of the light-emitting crystal on the three types of printed circuit boards under study was: 57,4 °C, 50,4 °C and 41,7 °C, which ensures a favorable temperature mode for the LEDs and contributes to their long service life. With an operating current of 100 mA, it is advisable to use a printed circuit board with a light-emitting crystal temperature of 57,4 °C, which has a lower manufacturing cost. The approximate service life of LEDs in this temperature mode of operation will be about 90 thousand hours.