[Hardware Network] 1, background:
LED semiconductor lighting as a new type of industry, the current certification of reference standards can not meet the rapid development trend. The first version of the UL870 released by UL on November 18, 2009 provides the industry with a standard for the safety of LED lighting devices. In UL8750, Powersuplies or Drivers (LEDDrivers) can be selected to use the CLASS2 power supply that meets UL1310, the power supply that meets the requirements of information technology safety UL60950-1, and the CLASS2 power supply other than the UL1012 standard. Structural evaluations are exempt from more electrical test items for the CALSS2 power supply and LVLE circuits. Although the EU has not yet developed a set of safety standards for LED light source products, some countries in the European Union (France, Denmark, etc.) have begun to require LED road lighting to meet CLASS2 power supply. Although domestic LED outdoor lighting fixtures have UL certification, they basically use the UL60950 standard certified power supply. With the in-depth development of the LED semiconductor industry, the use of CLASS2 power supply for LED light source products is a future development trend.
2. What CLASS2:
UL60950-1 (General Safety Requirements for Information Technology Equipment) classifies electronic equipment into three categories: CLASS1, CLASS2, and CLASS3 according to the degree of protection against electric shock hazards. CLASS1 equipment refers to other protective measures such as grounding in addition to the basic insulation protection; CLASS2 equipment refers to not only relying on basic insulation, but also adopting double insulation or reinforced insulation as electric shock protection measures, and its insulation protection effect Does not rely on protective grounding or installation conditions; Class CLASS3 devices are powered by a very low safety voltage (SELV) and are free of hazardous voltages. The CLASS2 power supplies covered by the UL8750 and UL1310 standards are all compliant with the UL60950 CLASS2 equipment against electric shock safety.
3, CLASS2 power supply definition:
The Class 2 PowerSource defined by the LED lamp safety standard UL8750 refers to the isolated power supply that meets the requirements of UL1310 (UL1310 is the safety standard for CLASS2 power supply units used indoors and outdoors), or the low voltage that meets the requirements of UL5085-3. Class2 and Class3 transformer-powered circuits. UL1310 defines the CLASS2 POWERUNITS as follows: in accordance with the international code ANSI/NFPA70, connected to the 15A or 20A 120-240Vac branch circuit and less than 150V ground, using DC isolation and AC insulation to provide DC and AC energy, expected A device that supplies energy to low voltage and electricity. And the CLASS2 power supply is a device with limited output voltage and energy capacity. Under any output load, the input power does not exceed 660W. UL1310 stipulates the assembly mechanical structure, performance test requirements and product labeling of CLASS2 power supply. The following is the analysis of the main electrical performance requirements and test specifications of CLASS2 power supply, and provides reference for UL certification of power supply modules for LED light source lamps.
4. Voltage limit of contactable live parts of CLASS2 power supply:
The output of the CLASS2 power supply unit specified in the UL1310 standard shall be provided with an output cord, terminal block, insulated lead or output terminal. After the protective cover, the partition or the protective tool that can be removed without using the tool, after the removal, according to different test needles (Fig. 1), the joint detector (Fig. 2) or the tactile detector (Fig. 3) The degree of contact with live parts has different requirements for the maximum voltage at the output.
Before testing, it is necessary to confirm that the uninsulated live parts must be fixed on the surface of the substrate or the fitting. The minimum acceptable spacing cannot be caused by the occurrence of swirl or displacement. At the same time, the live parts that may cause the call to be dangerous must be enclosed or placed. Access to dangerous places.
4.1CLASS2 power supply exposed terminal maximum contact voltage requirements and test methods:
The maximum voltage of the live parts that can be accepted by the CLASS2 exposed terminal is not more than 25N (5.62 lbs) using the detector (shown in Figure 2). Do not touch the detector with more than the following voltage: 1), sine Or non-sinusoidal AC peak 42.4V; 2), continuous DC 42.4V; 3), equal or less than 200Hz frequency, about 50 duty DC peak 24.8V; 4), DC and AC mixed peak 42.4V;
4.2 CLASS2 power supply Non-exposed terminal can contact the maximum voltage requirements and test methods of live parts:
The maximum voltage of the live parts that can be accepted by the CLASS2 power supply non-exposed terminal is: under the action of the test pin (Fig. 1) and the joint detector (Fig. 2) not exceeding 4.4N (1 lb), the following circuits and over The live parts of the voltage touch the test pin and the joint detector: 1) primary circuit; 2) sinusoidal or non-sinusoidal alternating current peak 42.4V; 3) continuous direct current 60V; 4) equal or less than 200Hz frequency, about 50 The DC current of the duty cycle is 24.8V.
5. Maximum output current and power limit and test method of CLASS2 power supply:
The maximum output current and power of the CLASS2 power supply are divided into two limits: the energy inherent limiting circuit (ENERGYLIMITINGCIRCUIT) and the non-inherent limiting circuit (NOTENERGYLIMITINGCIRCUIT). The maximum output current and output voltammetric value of the test should be determined using an ammeter and a power meter. When no load is applied, the test sample shall be de-energized and cooled to room temperature.
5.1. Limits and test methods for the maximum output current and power of the inherently limited power supply:
The energy inherently defined circuit is to limit the output of the power supply to the CLASS2 level or to an acceptable energy level. The power supply with inherently defined circuits is an inherently defined power supply (LPS) that is fixed to limit the power supply under any load conditions (including short circuit and The maximum output current of the unconnected output lines on the label shall not exceed the values ​​listed in Table 1, and the maximum output power shall not exceed 100 VA.
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