1. The current status of LED North American standards
LED energy saving lamp as a new product, the current North American product safety standard is not specifically for the technical requirements of such products. The test of LED products has become a topic in the industry. In view of the current industry situation, the US UL laboratory is organizing the preparation of LED energy saving lamp safety certification standard UL8750, which is still a draft and has not been officially adopted as the certification standard. Therefore, the authentication test of LED energy saving lamp has not been solved completely for the time.
The basic principle of the LED energy saving lamp is to convert the AC power into DC through the switch mode power supply module to power the light emitting diode. According to the basic principle and structure characteristics of LED energy-saving lamps, the MET laboratory proposed a testing scheme of transitional stage: the traditional energy-saving lamp America UL1993 certification standards (corresponding to the Canadian standard CAN/CSA-C22.2No.0, CAN/CSA-C22.2No.74), and a power supply module standard UL1310 or UL1012 (corresponding to the Canadian standard CAN/CSA-C22.2No.107) test certification of LED energy-saving lamp.
Two. Technical points in testing
According to UL1993, UL1310 and UL1012 standards, the key problems in the LED energy-saving lamp certification test are discussed.
1 materials
The LED energy saving lamp can be made into various shapes. Taking the fluorescent lamp type LED energy saving lamp as an example, its shape is like the ordinary daylight tube, and the power module and the light-emitting diode are packaged in the transparent tube shell of the fluorescent tube. The transparent polymer shell has the function of fire protection and anti electrocution in the product. According to the standard, the shell material of the energy saving lamp must be above V-1 grade, so the transparent polymer shell must use the material above the V-1 grade.
The point to note is that the thickness of the product shell must be greater than or equal to the thickness required by the V-1 grade of the raw material to meet the required V-1 level, and the fire rating and thickness requirements can be found on the UL yellow card of the raw material. In actual detection, it is found that in order to ensure the brightness of LED lamps, manufacturers often make transparent polymer shells very thin, which requires inspection engineers to pay attention to ensure that materials meet the required thickness of fire protection level. Because different raw materials have different thickness requirements for the same level of fire protection, some raw materials can meet the requirements of higher fire protection level under a smaller thickness. It is suggested that manufacturers choose the right raw materials to make product shells.
2. drop test
According to the product standard requirements, the product should simulate the drop test that may happen in the actual use process, and the product should fall from 0.91 meters high to the hard board, and the product shell can not break up and expose the dangerous parts inside. When the manufacturer chooses the material to be the shell of the product, it must consider this strength requirement.
3. resistance to electricity
The transparent shell encircled the power module, and the transparent shell material must meet the power requirement. According to the standard requirements, based on the condition of 120 volts in North America, the internal high voltage electrified parts and the outer shell are tested on the metal foil to withstand the AC voltage test of 1240 volts. In general, the thickness of the shell of the product reaches about 0.8 millimeters, and it can meet the test requirements of the electrical strength.
4. power supply module
The power module is an important part of the LED energy saving lamp, and the power module mainly adopts the switch power technology. According to the different types of power supply module, different standards can be considered for testing and certification. If the power module is a classII power supply, this can be tested with UL1310 for authentication. ClassII power is the use of isolation transformer, output voltage less than 60 VOLTS DC, current less than 150/Vmax ampere power. For non classII power supply, UL1012 is used to test the authentication. The technical requirements of these two standards are very similar and can be referred to each other. Most of the internal power modules of LED lamps are non isolated connected power supply, and the output DC voltage is also greater than 60 volts. Therefore, it is not suitable for UL1310 standard, but suitable for UL1012.
5. insulation requirements
Due to the limited internal space of the LED energy saving lamp, the insulation requirement between the dangerous charged parts and the metal parts should be paid attention to in the design of the structure. Insulation can be space distance and creepage distance, and it can also be an insulating piece. According to the standard, the space distance between the dangerous charged parts and the palpable metal parts should reach 3.2 millimeters, and the creepage distance should reach 6.4 millimeters. If the distance is not enough, the insulation piece can be added as additional insulation. The thickness of the insulation piece is greater than 0.71 millimeters. If the thickness is less than 0.71 mm, the product must be able to withstand the 5000V high voltage test.
6. temperature rise test
The temperature rise test is a necessary item for the product safety test, and the standard has a certain temperature rise limit for different components. At the stage of product design, the manufacturer should pay great attention to the heat dissipation of the product, especially for some parts (such as insulation, etc.).
If the components work in a high temperature condition for a long time, they are easily damaged, resulting in the danger of ignition or electric shock. The power module inside the lamp is in a closed and narrow space, and the heat dissipation is limited. Therefore, when choosing components, manufacturers should pay attention to selecting the specifications of the appropriate components, ensuring that the components work at a certain margin, so that the components are overheated under the condition of long term close to full load.
7. structure
The power module of LED energy saving lamp is installed inside the shell, with limited space. Some manufacturers are able to save the space to weld the pin type components on the PCB, which is not acceptable. These surface welded pin elements are likely to be made of