Why Are LEDs so Popular? Discussion on Connector of LED Lighting Standard

Light emitting diodes (LEDs) have revolutionized indoor and outdoor lighting. This solid-state lighting (SSL) technology has excellent efficiency, controllability, chromatography, thermal performance and unique shape. It is eliminating the ancient Edison incandescent bulbs (as well as fluorescent lamps, metal halide lamps or sodium vapor lamps). Now, most new indoor and outdoor designs and upgrading of existing designs will first consider led. However, designers should be careful. At the same time of rapid innovation, there will also be some hidden dangers, such as non-standard connection and end-user solution mismatch, which will cause a negative customer experience.

It is not just the light source itself that has been completely changed. For example, LED lighting is also changing the design and shape of connectors and their fixtures (called lamps). These connectors are an essential part of any lighting system. They do not accept AC line voltage, but lower DC voltage. The typical current is usually between 3 A and 7 a. In addition, LED lighting system is usually part of the control network supporting digital addressable lighting interface (DALI) and zhaga industry standard, and provides intelligent, energy-saving and high-performance lighting as a key link of smart home or office.

Therefore, before designing LED lighting system, engineers have the responsibility to be familiar with these standards and their reflection in real-world connectors, because new designs are rising rapidly.

This paper briefly reviews why LEDs are so popular, and then introduces and describes these two connection standards to ensure interoperability, rapid development and easy deployment of intelligent LED design. Finally, the connectors of Amphenol ICC are introduced, and as the practical embodiment of relevant standards and their applications, the application of these connectors is summarized.

Why are LEDs so popular

There are many factors promoting the development of led into lighting source:

Cost reduction promotes the increase of output, which further promotes the reduction of cost and the increase of output

Basic reliability and life enhancement of LED as light source

The improvement of the circuit is mainly the improvement of the power supply driving these LEDs

Improvement of optical output quality characterized by color temperature (Kelvin) and color rendering index (CRI)

Incentives, standards and enforcement measures taken by the government to improve lighting efficiency to save energy (it is estimated that lighting accounts for 15% to 20% of total energy consumption)

Development of industry and government standards that ensure interoperability between LED light sources and compatibility with intelligent controllers.

The last point is particularly important. An important size category of traditional incandescent bulbs is the "E26" 26 mm (mm) diameter Edison screw bulb, which is almost commonly used in residential environments in the United States and many other countries (Figure 1). It is being replaced by LED and fluorescent bulbs, but to a lesser extent. Of course, there are other sizes, such as E12 base, but E26 is the most widely used at present.

Of course, standardizing to a single base and socket can reduce costs. The same technology has also led to a variety of bulb shapes, power levels and other attributes built around this foundation, while reducing concerns about long-term replacement of burned bulbs. Early generations of LED bulbs used E26 base to be compatible with existing sockets, making users accustomed to LED lighting. These E26 LED bulbs are still widely sold because there are countless such sockets in use, so the replacement process will take a long time.

However, compared with incandescent lamps, LEDs are very different in current, voltage (DC) and power consumption. Incandescent bulbs usually use 120 / 240 V AC power supply. In addition, the wire of E26 socket often has relatively large threaded terminals, which is not ideal for LED light source power supply (Fig. 2). Therefore, new standards and connector types are needed in order for LEDs to give full play to their potential from the system level to the physical connection level.

Recognizing the needs of modern lighting interface standards, the Digital Lighting Interface Alliance (diia) developed the Dali standard.

The Dali standard redefines lighting connections

Dali is a special protocol for digital lighting control, which can easily realize firm, scalable and flexible lighting network installation (Figure 3). The first version dali-1 is more suitable for digital control, configuration and query of fluorescent lamp ballasts, and less led factors are considered. It replaces the simple, unidirectional and broadcast operation of the existing 0 / 1 to 10 volt analog control mode.

The standard also includes a broadcast option. Through simple reconfiguration, each Dali device can be assigned a separate address, allowing digital control of a single device. In addition, Dali devices can also be programmed for grouping operation, so that the lighting system can be reconfigured through software to avoid changing wiring.

With the growth of user expectations and the improvement of LED technology, the development of dali-2 standard is promoted. Dali-2 is not only an industry standard, but also a standard of the International Electrotechnical Commission (IEC 62386). Dali-2 adds many new commands and functions. Dali-1 only includes control mode, while dali-2 covers control devices, such as application controllers and input devices (such as sensors), as well as bus power supply. It focuses on the interoperability of products from different manufacturers, and is supported by dali-2 certification plan to confirm the compatibility between products and specifications (Figure 4).

Like all comprehensive standards, dali-2 is complex. In short, with a single line pair as the bus, each device on the Dali network can be addressed separately. The bus is used to provide both signals and power. The supported power supply can provide up to 250 Ma at 16 V DC (typical). This standard supports equipment powered by AC lines or DC power rails.

Although various standards define ultra-low voltage (ELV), IEC defines ELV equipment or circuit as: the potential difference between electrical conductor and grounding does not exceed AC 50V or DC 120V. Dali control cable is classified as ELV equipment, so it only needs to be basically insulated from AC mains power; It can be routed together with mains lines or multi-core cables including mains lines.

Beyond dali-2: zhaga specification, aiming at lamps

Dali-2 and other standards are important, but they can only stop there. It is not within the scope of its definition to define how to link standards to specific applications, such as LED lighting and lamps. In order to solve this problem, the international zhaga alliance has formulated the interface industry specification of components used in LED lamps. The alliance is a member project of IEEE industry standards and technology organization. As of 2019, it has more than 120 members.

It's time to find out the difference between lighting equipment and lamps. The term "luminaire" is used in the lighting Engineering Society (ies) lighting manual, ANSI / NEMA standards and IEC. It was added to the National Electrical Code (NEC) manual in 2002 and is officially defined as "a complete lighting unit consisting of one or more lamps and components designed to distribute light, locate and protect the lamp tube and connect the lamp tube to the power supply". Lamps include lamps and all parts directly related to the distribution, positioning and protection of lighting devices, excluding supporting parts, such as arms, ribs or rods; Fasteners for fixing lamps; Control or safety devices; Or power lead. Lamps have a variety of forms and are suitable for various occasions, from outdoor street lighting with strict functions to indoor office lighting, and even "fashionable" retail or home lighting.

"Lighting equipment" is not defined in NEC and generally refers to anything in the mind of the user, which may include some or all of the following elements: lamp tube (bulb), perhaps with lampshade, lamp ball, lens or diffuser, support, lamp pole or lamp accessories, and other elements.

The official name of the zhaga specification is books (specification), which aims at electrical, mechanical, optical, thermal and communication interfaces and allows the interoperability of components. By following the zhaga specification, designers can ensure that users have interoperable, replaceable or repairable components, and that led lamps can be upgraded when new technologies appear after installation.

Zhaga Book 18 and book 20 are particularly useful for designers who use LED lamps; The former focuses on outdoor design, while the latter is for indoor applications.

Zhaga Book 18: "intelligent interface between outdoor lamps and sensing / communication modules" specifies the contents of power supply and communication. In addition, it also specifies the mechanical coordination and electrical pins of the connection system defined in version 1.0. It simplifies the addition of application modules, such as adding sensors and communication nodes to LED lamps, and ensures plug and play interoperability.

Zhaga book 20: "intelligent interface between indoor lamps and sensing / communication modules" defines the intelligent interface between indoor LED lamps and sensing / communication nodes. The node is connected to the LED driver and control system, and can usually provide sensor input or realize communication between network components. Nodes can be installed and replaced on site.

epilogue

LED lighting has greatly changed the indoor and outdoor lighting of industry, commerce and residence. It combines energy efficiency, long life and flexibility of lamp configuration almost perfectly.

Editing: hfy

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