Technical points on the detection of LED energy-saving lamps in North America

First, the status of LED North American standards

LED energy-saving lamps as a new type of product, the current North American product safety standards do not specifically address the technical requirements of such products, LED product testing has become a topic in the industry. U.S. UL Laboratories is currently organizing the preparation of LED energy-saving lamp safety certification standard UL8750 for the current industry situation. This standard is still a draft and has not been formally adopted as a certification standard. Therefore, the certification test of LED energy-saving lamps has not been completely resolved.

The basic principle of the LED energy-saving lamp is to convert the AC power to DC through the switching power supply module to supply power to the LED. According to the basic principles and structural characteristics of LED energy-saving lamps, the US MET laboratory proposes a transitional testing program at the present stage: the adoption of the traditional certification standard UL 1993 for energy-saving lamps (corresponding to the Canadian standard CAN/CSA-C22.2No.0, CAN/ CSA-C22.2 No. 74), and the power module standard UL1310 or UL1012 (corresponding to the Canadian standard CAN/CSA-C22.2 No. 107) test and certification of LED energy-saving lamps.

Second, the technical point of detection

The following describes the key issues in the certification test of LED energy-saving lamps according to the UL1993, UL1310 and UL1012 standards.

1. Material

LED energy-saving lamps can be made into various shapes. Take the fluorescent tube type LED energy-saving lamps as an example. The shape of the energy-saving lamp is the same as that of an ordinary fluorescent tube. The power module and the light-emitting diodes are enclosed in a tubular fluorescent transparent polymer tube. The transparent polymer shell plays a role in preventing fire and electric shock in the product. According to the standard requirements, energy-saving lamp housing materials must be above the V-1 level, so the transparent polymer housing must use materials above the V-1 level. The point to note is that the product enclosure must meet the required V-1 rating, its thickness must be greater than or equal to the thickness required for the V-1 grade of the raw material, and the fire rating and thickness requirements can be found on the UL yellow card of the raw material. . The actual detection found that manufacturers in order to ensure the brightness of the LED lamp, the transparent polymer shell is often made thin, which requires the inspection engineer to pay attention to ensure that the material to achieve the required level of fire protection. Since different raw materials have different thickness requirements for the same fire rating, certain raw materials can meet higher fire rating requirements at a relatively small thickness, and manufacturers may be advised to choose suitable raw materials for the product enclosure.

Drop test

According to the product standard requirements, the product is to be simulated as a drop test that may occur during actual use. The product should be dropped from a height of 0.91m to a hardwood board, and the product enclosure must not be broken to expose the hazardous live parts inside. Manufacturers must consider this strength requirement when selecting materials for product enclosures.

3. Electrical strength

The transparent housing surrounds the power module and the transparent housing material must meet the electrical strength requirements. According to the standard requirements, based on the conditions of the North American voltage of 120 volts, the internal high-voltage live parts and the housing (to be covered with metal foil for testing) should be able to withstand the AC strength test of 1240 volts. Under normal circumstances, the product shell thickness of about 0.8 mm, you can meet this test requirements for electrical strength.

4. Power module

The power module is an important part of the LED energy-saving lamp. The power module mainly uses the switching power supply technology. According to different types of power supply modules, different standards can be used for testing and certification. If the power module is a class II power supply, this can be tested using the UL1310 certification. The class II power supply refers to an isolated transformer with an output voltage lower than 60 volts DC and current less than 150/V max amps. For non-class II power supplies, UL1012 is used for testing and certification. The technical requirements of these two standards are very similar and can be used as a reference. Most of the LED lamp's internal power supply module uses a non-isolated power supply, the power supply output DC voltage is also greater than 60 volts, it is not applicable UL1310 standard, and applies UL1012.

5. Insulation requirements

Due to the limited interior space of LED energy-saving lamps, attention must be paid to the insulation requirements between hazardous live parts and accessible metal parts during structural design. Insulation can be a space distance and a creepage distance, or it can be an insulation sheet. According to the standard requirements, the space distance between hazardous live parts and accessible metal parts is 3.2 mm, and the creepage distance is 6.4 mm. If the distance is not enough, you can add insulation as an additional insulation, insulation thickness greater than 0.71 mm, if the thickness is less than 0.71 mm, the product must be able to withstand 5000V high voltage test.

6. Temperature rise test

Temperature rise test is a must-do item for product safety testing. The standard has a certain temperature rise limit for different components. In the product design stage, manufacturers must pay great attention to the heat dissipation problem of the product, especially for certain components (such as insulation sheets).

Parts that are exposed to high temperatures for a long period of time are easily damaged and cause fire or electric shock. The power module inside the lamp is in a closed and confined space, and the heat dissipation is limited. Therefore, when manufacturers make component selections, they must pay attention to selecting the specifications of suitable components to ensure that the components work under a certain margin, so as to avoid overheating when the components work under near-full load conditions.

7. Structure

The energy-saving lamps of LED energy-saving lamps are installed in the interior of the enclosure, and the space is limited. Some manufacturers, in order to save space, solder the surface of the pin-type components to the PCB. This is unacceptable. These surface-welded pin-type components are likely to be detached due to imaginary welding and other hazards. Therefore, jack soldering should be used as far as possible for these components. If it is necessary to adopt the surface welding method, additional protection shall be provided to the component by means of glue fixing.

8. Fault testing

Product failure testing is a crucial test item in product certification testing. This test item is short-circuited or open circuit components on the circuit to simulate possible failures during actual use, thereby assessing the product's safety under a single fault condition. In order to meet this safety requirement, it is necessary to consider adding an appropriate fuse to the input of the product during product design to prevent overcurrent due to output short-circuit or internal component failure, which may cause fire hazard.

Third, the factory inspection

North American product certification requires factory inspections. Factory inspections include first factory inspections and follow-up inspections. If the factory is applying for North American product certification for the first time, a first factory inspection is required. The first factory inspection is mainly aimed at the factory's quality assurance system. It requires the factory to have a perfect quality assurance system to ensure that the product quality is effectively supervised and guaranteed. If the factory has established a quality management system according to ISO9000 standards and passed the ISO9000 certification, it can basically meet the requirements of the first factory inspection management system. If the factory does not pass the ISO 9000 certification, it must have clear procedural documents in terms of raw material procurement, incoming materials inspection, inventory management, product design, engineering changes, production line testing, instrument calibration, and complaint follow-up. Subsequent follow-up inspections are mainly directed at product structure inspections and production line product testing, etc. to ensure that the product structure produced by the production line is consistent with the certified samples and passes the relevant production line tests. After the product passes the test and certification, the manufacturer must strictly follow the structure and component list of the certified sample for product production. Any changes that may involve product safety must be notified to the certification body for evaluation. If necessary, retesting and reporting changes may be required. The product test report has specific requirements for the production line test of the product. The manufacturer must perform related tests such as high voltage test and ground continuity test according to the requirements.