LED has the advantages of energy saving and environmental protection, and the development in the lighting industry has become a major trend. Because the technology and product attributes used by LEDs are very different from traditional lamps, the current general safety standards for lamps are obviously not applicable. To help the industry address this issue, this issue will explain the technology used in LED luminaires, the scope of possible applications, and the safety assessments currently used by UL.

LED Lighting Technology and Features

The so-called LED luminaire, as its name implies, refers to the use of LED (Light-emitting Diode) technology as the main light source. LED is a solid-state semiconductor component. It uses current to flow in the direction of the semiconductor pn junction coupling, and then the negatively charged electrons and positively charged holes in the semiconductor are combined with each other to generate photons Emission, different types of LEDs can emit light with different wavelengths from infrared to blue, and purple to ultraviolet. The new development in recent years is to apply fluorescent powder to blue LEDs to convert blue LEDs into white LED products. This operation generally requires a driver circuit (LED Driver) or power supply (Power Supply). The main function of the drive circuit or power supply is to convert AC voltage to DC power, and at the same time complete the voltage and current corresponding to the LED To drive cooperating components.

The LED light bulb has a small size, light weight, and is encapsulated with epoxy resin. It can withstand high-intensity mechanical shock and vibration, is not easily broken, and has a long brightness decay period, so its service life can be as long as 50,000-100,000 hours, far exceeding the traditional 1,000 hours for tungsten bulbs and 10,000 hours for fluorescent tubes. Since the service life of LED lamps can reach 5 to 10 years, not only can it significantly reduce the cost of lamp replacement, but also because it has the characteristics of extremely low current that can drive light. Under the same lighting effect, the power consumption is only One-half of the fluorescent tubes, so LED also has the advantages of power saving and energy saving.

However, because some LED technologies are still inadequate, the initial disadvantages of using them in lamps include poor light quality (color rendering, consistency, color temperature), poor heat dissipation, and high prices, and improper heat dissipation among them As a result, the brightness of LED lamps and the service life of circuit components are accelerated.

With the rapid development of manufacturing technology in the past ten years, the above disadvantages, including the thermal resistance of LEDs, have gradually decreased, and the light quality has also been improved. In 2008, in addition to the LED white cold light, the luminous efficiency has reached 100 Lm / W, and the LED warm white light luminous efficiency is expected to increase from the current 70 Lm / W to 100 Lm / W in 2010. Compared with other current general-purpose light sources, tungsten filament bulbs are about 15 Lm / W, fluorescent fluorescent lamps are about 45 ~ 60 Lm / W, and HID lamps are about 120 ~ 150 Lm / W. The luminous efficiency of LEDs has clearly become gradually superior. Comparison of light properties for LED and other common lamps:

Lighting method

Features

White LED

Fewer heat sources, wide operating environment, miniaturization, vibration resistance, and concentrated beam

Daylight (Fluorescent) Light

Fluorescent lamps save electricity, but the waste is fragile and has mercury pollution.

Incandescent tungsten light bulb

Low efficiency, high power consumption, short life, fragile

Lighting method

Features

 Safety regulations for LED lamps

With the improvement of technology, the use of LED lamps has been used in indicator lights and signal lights for decades. It has gradually been used in auxiliary lighting such as mobile phone backlights, interior lighting, brake lights, LCD TVs, and laptop computer backlights. ; In the past two years, it has become the main lighting system, and its applications can include construction, outdoor, commercial, and home. The products are:

Base), including driving circuit

North American market. North American market requires E26 Base

LED bulb (not ANSI Base) with driver circuit

UL 496

LED module without driver circuit

UL 60950-1

LED driver

Power supply (with LPS safety circuit)

UL 60950-1

Output LPS safety circuit, the LED module and LED control module do not need electrical enclosure (Enclosure)

Power supply (without Class 2 safety circuit)

UL 1012

LED modules and LED control modules need to provide proper electrical enclosure protection

Power supply (with Class 2 safety circuit)

UL 1310

Output Class 2 safety circuit, LED module and LED control module do not need electrical enclosure (Enclosure)

Driver (with LPS / Class 2 safety circuit)

UL 935

Output LPS / Class 2 safety circuit, then the LED module and LED control module do not need an electrical enclosure (Enclosure)

Low voltage garden light power supply

UL 1838

LED modules and LED control modules need to provide proper electrical enclosure protection

  Subject 8750 Security Evaluation and Testing

After a brief understanding of the standards that each product should refer to, the subject 8750 that is complementary to the above standards will be briefly explained below. Subject 8750 has been updated to the 3rd revised edition. The content is divided into 12 chapters, of which chapters 1-4 are: general chapters including scope, definitions, etc .; chapters 5-9 are: structural requirements; chapters 10-11 are : Test evaluation; Chapter 12: product labeling. The following is a statement of the two major content frameworks, including "structural requirements" and "test evaluation". However, readers are particularly reminded that because the product uses and environmental requirements of each safety standard are different, the degree of adoption of the Subject 8750 provisions is naturally different.

I. Structural requirements (chapters 5-9)

1. Use environment considerations: The product is used in different environments, such as dry, damp, outdoor (Wet) and other places. The safety standards for the distance between charged bodies, plastic housing, testing, warning signs (Marking) Wait, there will be different requirements.

2. Mechanical structure requirements: The safety requirements of the shell are the first in this part, and the focus is on the performance of fire resistance, electric shock resistance, and anti-collision. In addition, the thickness of the metal shell, the corrosion resistance, and the physical characteristics of the plastic shell are also required. There are other regulations on partitions, internal line protection, tensile strength, and glue filling.

3. Electrical structure requirements: including avoiding contact with dangerous live objects, exposed junction terminals, internal junctions, connection between power supply and load ends, circuit isolation, use of insulating materials, specifications of printed circuit boards, Spacing, electronic components, protective devices, and energy limits for Class 2 or LPS safety circuits are all within the scope of this section.

4. Other requirements: such as LED power supply, LED array, LED module, LED control module and other safety and enclosure requirements. LED power supplies can be power supplies certified by the following standards, including UL 1012, UL 1310 and UL 60950-1. Basically, the number of LEDs

category

product

Architectural lighting

Garden lights, searchlights, step lights, balcony lights, etc.

outdoor lighting

Street lights, pole lights, etc.

commercial lighting

Advertising lighting, display cabinet lighting, etc.

Home lighting

Lamps, ceiling lamps, wall lamps, kitchen cabinet lamps, standing lamps, table lamps, etc.

 Safety regulations for LED lamps WP6 safety regulations and electromagnetic compatibility network WP6 safety regulations and electromagnetic compatibility WP6 safety regulations and electromagnetic compatibility network

Feeling the improvement of LED light source manufacturing technology and the broadening of the application level, and the current UL lighting product safety standards have no clear specifications for LED light sources, so in 2005, UL began to draft safety regulations for LED light source products. — Subject 8750, supplements the deficiencies of safety standards for lighting products with a standardized general structure evaluation, and plans to officially become the UL 8750 safety standards in the future as a safety test for all lighting products using LEDs as the light source mostly according.

• Classification of LED lamps in UL standards

The following is the classification of three basic products, such as LED lamps, LED bulbs, and LED drivers, and the UL safety standards and special precautions that should be referred to when they are used in each finished product or part. Basic guidelines for safety testing. However, this table is only for readers' reference. The actual classification of products must still be determined according to the use of the product and its use environment.

Application products

Safety standards

Precautions

LED Lighting

Indicator light

UL 48

-

Handle lamp, kitchen cabinet lamp, table lamp, stand lamp, wall lamp, etc. (all with power cord plug)

UL 153

Covers portable luminaires, plugged into a branch circuit labeled 120 volts 15 or 20 amps via a power cord plug

Christmas lights string

UL 588

-

Emergency light, exit light

UL 924

-

Display cabinet, mirror light

UL 962

-

Stage lights

UL 1573

-

Step lights, lights, ceiling lights, chandeliers, wall lights, street lights, pole lights, etc. (all without power cord plug)

UL 1598

Covers fixed luminaires for use in non-hazardous areas and installed on branch circuits below 600 V.

Night light

UL 1786

-

Low voltage garden light (without power cord plug)

UL 1838

-

Water pipe light

UL 2388

-

LED bulb

Indicating bulb

UL 496

-

LED bulb (ANSI Base) with driver circuit

UL 1993

E27 Base is a European standard and cannot be used in the North American market. North American market requires E26 Base

LED bulb (not ANSI Base) with driver circuit

UL 496

-

LED module without driver circuit

UL 60950-1

-

LED driver

Power supply (with LPS safety circuit)

UL 60950-1

Output LPS safety circuit, the LED module and LED control module do not need electrical enclosure (Enclosure)

Power supply (without Class 2 safety circuit)

UL 1012

LED modules and LED control modules need to provide proper electrical enclosure protection

Power supply (with Class 2 safety circuit)

UL 1310

Output Class 2 safety circuit, LED module and LED control module do not need electrical enclosure (Enclosure)

Driver (with LPS / Class 2 safety circuit)

UL 935

Output LPS / Class 2 safety circuit, then the LED module and LED control module do not need an electrical enclosure (Enclosure)

Low voltage garden light power supply

UL 1838

LED modules and LED control modules need to provide proper electrical enclosure protection

As long as the group, LED module and LED control module are located on the LPS / Class 2 safety circuit, there is no requirement for any electrical enclosure. The requirements for the power output mode of LED lamps are basic insulation, which is the same as no isolation at all. For LED arrays, LED modules and LED control modules, if the power used does not need to exceed LPS / Class 2, it is recommended to comply with LPS / Class 2. Conversely, if the energy used will be greater than LPS / Class 2, is there no insulation to isolate the primary and secondary power circuits, and there is no difference in the requirements for the plastic case.

Test Evaluation (chapters 10-11)

In the test project part of Subject 8750, UL often tests the product as follows: Input Test, LED Module Normal Operations Temperature Test, Dielectric Voltage Withstand Test, Abnormal Abnormal Condition Tests, Unreliable Component Abnormal Test, 50-W Point Power Measurement Test, etc.

• New Product Category (CCN) for LED Lighting

Due to the increasing scope of LED luminaire applications, this year UL has defined some new product categories (CCN) related to LED applications, such as OOQA2 (LED module, UL 8750), FKSZ (LED driver, UL935), OOLV (Energy-saving light bulbs, UL1993), QOVZ (portable LED lamps, UL153), QOVA (LED kitchen light, UL153), IFAM (LED fixed lamps, UL1598), IFAO (LED? Lamps, UL1598), etc. Apply for UL safety regulations based on different product categories. Here are examples of CCNs that are more closely related to the industry, including OOQA2 and FKSZ, as defined below:

CCN

definition

OOQA2

It is a module of LED light source, which can be integrated by the lamp manufacturer in the assembly of the lamp