The thermal design of explosion-proof lamps is an important design work to ensure the normal working life of the light source and the normal and safe operation of the lamps. From the perspective of installation, use, maintenance and transportation of lamps, the smaller the volume, the better, and the more compact the parts are, the better. The lighter the weight, the better. However, from the perspective of heat dissipation and optics of lamps, explosion-proof lamps need to have a certain size.
Since explosion-proof lamps are closed lamps, it is difficult to dissipate heat from the light source, and the temperature rise of each component of the lamp increases, which not only affects the life of the light source and insulating materials, but also brings problems to explosion-proof electrical safety.
Therefore, more comprehensive requirements must be put forward for heating conditions, so that explosion-proof lamps can ensure safe, efficient, normal and stable working conditions for a long time.
(1) The lamps and lanterns shall not become inoperable and unsafe common phenomena after the durability test.
① The light source is continuously damaged during the test, which may be due to the high temperature of the lamp cavity, which affects the life of the light source.
②The electrical components cannot provide electrical parameters that meet the requirements, so that the light source cannot work normally.
③ Signs of damage that may be unsafe include cracking, charring and deformation.
(2) Test conditions
① The explosion-proof lamps are placed in an environment that is 10°C higher than the rated maximum ambient temperature according to the normal working position.
②Test time: For lamps that work without abnormal conditions, the test should be 10 days; for lamps that work under abnormal conditions, the test time is 7 days. The first 6 days are normal work and the 7th day is abnormal work.
③ Abnormal operation refers to working under the most severe conditions for heat, such as possible changes in the installation position, possible failure of the electrical circuit (short circuit of the starter contacts, etc.).
④Test voltage: For tungsten filament lamps, it should be 1.05 times the voltage when the light source reaches the rated power, and for tubular fluorescent lamps and other gas discharge lamps, it should be 1.1 times the rated voltage.
Explosion-proof lamps that are not damaged after the durability test and whose other properties meet the relevant requirements can be considered to be able to work stably for a long time.
2. Thermal performance
Explosion-proof luminaires cannot be rendered unsafe by overheating under normal or abnormal operating conditions.
(1) Explosion-proof lamps are placed in the anti-ventilation hood, excluding the influence of atmospheric convection on the test, and can use 1.1 times the rated voltage. The lamps must be inclined upwards, upwards of 45°, horizontal, downwards of 45°, and downwards in five positions respectively. To measure the temperature, if it is stipulated that the lamp is only used in a certain position, the temperature can be measured only according to the specified position. The maximum allowable surface temperature of explosion-proof lamps shall not be higher than the allowable temperature of the temperature group marked by it.
Under normal working conditions, all temperatures of lamps and lanterns shall not exceed the required corresponding values by more than 5°C.