The LED has come a long way since its invention more than 50 years ago. From instrumentation indicators to digital clocks to holiday displays and more recently smart buildings, the application options for LEDs seem limitless. As environmental awareness increases, more consumers look to benefit from the energy efficiency and durability of LED lighting systems.
LED street light
Municipalities also increasingly look to tap into these benefits by replacing dated energy-guzzling streetlights with more efficient LED street lighting. Manufacturers responded to the demand by forming partnerships and developing the LED technology to meet the more rigorous standards for street lights. Along with decisions about illumination, color, intensity, connectivity and ingress protection, the most important consideration for a street lighting retrofit must be the driver which supplies the power and controller to the LED. So what are some key factors to consider when choosing an LED driver for a street lighting system?
LED streetlights must be durable as well as easy to maintain. More and more manufacturers are responding to this demand by designing systems with remote LED drivers that reside in the junction box at the base of the streetlight instead of inside the fixture at the top of the pole. This allows for easier maintenance as the driver tends to be more prone to failure than the LED. Easier maintenance means added savings to municipalities.
Remote drivers also play a role in LED thermal management. LED drivers are traditionally built into LED fixtures on the head in front of the LED module. During the voltage conversion process, LED drivers produce thermal energy which gets trapped in the housing and transferred to the LED. High temperatures lead to premature failure. LED fixtures with remote drivers are exposed to less heat and are therefore more durable than their built-in counterparts.
Multiple LED street light installation
LEDs operate at low voltages and are more sensitive to overvoltage than traditional bulbs. Standard LED drivers are designed to withstand overvoltages from 2kV to 4kV, but streetlights are subjected to much higher degrees of voltage fluctuations. Power grid overvoltages, for example, can reach as high as 6kV while lightning strikes are known to generate overvoltages as high as 10kV. Electrostatic discharge (ESD) generated during routine maintenance can also impact unprotected LEDs.
High overvoltages can cause high currents and the premature aging of LEDs, leading to reduced service life and decreased economic benefit to municipalities. Designers must, therefore, consider adding a quality surge protector aptly rated for the intended application environment.
If future expandability is critical, then controller capabilities must also be a consideration. Digital Addressable Lighting Interface or DALI-based controllers are becoming increasingly popular for street lighting control. Not only because they can be upgraded to wireless, but also because these controllers offer greater compatibility with existing lighting control systems. DALI controllers are simple, scalable, flexible and robust. DALI can control individual LEDs or even groups of LEDs and are easily reconfigurable for changing conditions.
Rapidly evolving LED technology has opened the door to new applications in public street lighting as cities worldwide seek to reduce costs and improve night visibility. The complexities of municipal street lighting require that designers consider many factors when specifying a conversion, chief among which are LED driver attributes. The most effective drivers are easy to maintain, offer surge protection, lighting control and ensure LED longevity.
References
Bullough, J. D., Lighting Research Center., New York State Energy Research and Development Authority., & New York (State). (2012). Guide for optimizing the effectiveness and efficiency of roadway lighting. Troy, Ny.: Lighting Research Center.
Drivers enable next-gen LED street lighting. (January 01, 2012). Electronic Products New York-, 54, 12, 44.
Signorino, I. (May 01, 2012). Drivers enable next-gen LED street lighting: What designers must consider when selecting a driver, focusing on why eliminating the step-down transformer is a good idea. Electronic Products, 54, 5.)
LED drivers, or LED power supplies, provide LED light bulbs with the electricity required for peak performance, much like a fluorescent lamp’s magnetic ballast or a low-voltage bulb transformer. The steady stream of technological innovations and the often-confusing terminology can make LED driver selection seem overwhelming even to seasoned professionals. The goal of this article is to answer some of the most common questions and help the lighting designer/specifier navigate the intricate labyrinth of LED driver selection.
Energy efficiency is the main reason customers hunger for solid state LED lighting control systems. The use of high-efficiency drivers increases the energy savings that can be achieved. Higher efficiency power supplies dissipate less heat and result in improved product lifetime.
Other factors to consider are reliability, function, and usability. Not all drivers are alike. Consider the benefits of taking the modular route. The main benefit is that it frees the user to mix and match what they need at the right price without having to over-engineer. To that regard, our modular systems approach is unique. To learn more about LED drivers and power supplies, please visit GREAlpha.com or the referenced articles below.
References
Corrie, A. (January 01, 2013). LED Lighting Depends On Drivers. Electronic Design, New York,
61, 5, 74.
Wang, Y., Alonso, J. M., & Ruan, X. (July 01, 2017). A Review of LED Drivers and Related Technologies. Ieee Transactions on Industrial Electronics, 64, 7, 5754-5765.
Industrial lighting control systems generally aim to maximize energy savings, satisfy building codes, or comply with green building and energy conservation programs. These Smart Lighting systems are fast becoming a staple in modern commercial architectural design. Today’s lighting components must be able to “talk” to one another, meaning they must use the same communication protocols to trigger specific actions, such as synchronizing and dimming light fixtures. Popular wireless protocols include Infrared, Bluetooth, Wi-Fi, Zigbee, Thread, Z-Wave and KNX. The number of wireless networking options is increasing.
With so many connection protocols available, it is essential for smart system designers and specifiers to understand the fundamental similarities and differences among various wireless protocol brands. This article identifies standard features as well as dissimilarities among three popular wireless protocols – Bluetooth®,Wi-Fi® and Zigbee– and outlines best industrial lighting applications for each technology.
Short for Wireless Fidelity, Wi-Fi® networking is a growing trend in smart building design. Wi-Fi® first gained popularity for media streaming gaming, browsing the web and other data-heavy activities because of its high bandwidth capability. Wi-Fi® uses radio frequency to transmit data through the air.[1] The communication protocol is stable and cost-effective, yet traditionally many designers avoided the technology in industrial applications because of its high power requirements. Recent improvements to Wi-Fi® power efficiency has prompted many designers to reconsider the technology for industrial lighting applications. Because of the limitations on the number of network-connected devices, the technology is more suitable for small commercial lighting applications.
Zigbee is an open wireless communication protocol based on the IEEE 802.15.4 technical standard. This openness leads to greater competition and innovation among developers. Its maximum speed of 250 kbps at 2.4 GHz makes it slower than other popular wireless standards. However, ZigBee shines in comparison to the other wireless protocols in power consumption efficiency. Zigbee was designed to transmit small packets of data at relatively infrequent intervals, making it easy to connect battery-operated devices such as LED lighting.
The Zigbee protocol supports star, tree and mesh networking topologies. Mesh-networked devices use each other to transmit signals; often referred to as many-to-many (m:m) communication. Single device malfunctions do not interrupt the network. Mesh networking topology strengthens connectivity and increases network scalability, opening the pathway for designers to incorporate the technology in increasingly sophisticated industrial lighting applications.
The newest version, Zigbee 3.0, further standardized the protocol, allowing for seamless compatibility among all Zigbee-certified devices regardless of branding. Zigbee aims to be the global standard for all “Internet of Things” (IoT) solutions. According to the Zigbee Alliance, the IoT market is expected to grow from $180 million in 2014 to more than $1 trillion by the year 2020.[2] It is no surprise, therefore that manufacturers, like GRE Alpha® Electronics, are jumping at the chance to get in on this technology. The company specializes in the design of solid-state lighting power supplies and lighting control accessories and is a trailblazer in the design of Zigbee-certified devices. Its SLD-SMARTDIM wireless dimming module, for example, is Zigbee-enabled and compatible with a wide variety of smart switches and controls. The module delivers flicker-free 0-100% dimming and a fast response time for easy control of constant voltage LED fixtures.[3]
Released in 2000 and originally designed to replace serial cables and support wireless audio applications, Bluetooth is arguably the most widely recognized wireless connectivity brand. The newest version, Bluetooth Low Energy (LE), uses very little power compared to the original variety. The addition of mesh networking support in the summer of 2017, opened the floodgates to sophisticated industrial lighting applications.
Often referred to as Smart Bluetooth, the mesh-based LE technology is not prone to signal loss like the Wi-Fi protocol. Like Zigbee, the technology supports complex many-to-many device communication, and networks can be designed to cover large physical areas. The technology is also interoperable across products from different vendors and is secure, scalable and upgradeable, making it a key player in the IoT market and especially suitable for large-scale industrial lighting automation applications.[4] GRE Alpha recently partnered with the EnOcean Alliance to further develop its wireless offerings to Bluetooth® LE-enabled devices and other wireless applications.[5]
Continued advances in these wireless technologies are ushering building design into an era of all-in-one facility automation, increased energy savings, greener construction practices and straightforward code compliance.
Table 1. Specification comparisons
|
Wi-Fi® |
Zigbee |
Bluetooth® LE |
Cost |
Medium |
Low |
Low |
Power consumption |
High |
Low |
Low |
Operating range |
150 feet |
35 feet |
330 feet |
Max. # of devices |
250 |
65,000 |
32,000 |
Data rate |
11 Mbps / 54 Mbps |
40 - 250 kbps |
1 Mbps |
Frequency |
2.4 GHz |
915 MHz/2.4 GHz |
2.4 GHz |
Network topology |
Infrastructure Ad hoc |
Star Tree Mesh |
Point to Point Broadcast Mesh |
Hub needed |
Yes |
Yes |
Yes |
Security |
Minimal |
128 AES plus application layer security |
64 and 128-bit encryption |
Proprietary |
Yes |
No |
Yes |
Scalable |
No |
Yes |
Yes |
Suitable applications |
Small Commercial |
Large Industrial |
Large Industrial |
[1] (Wi-Fi Alliance, 2017)
[2] (Zigbee Alliance, 2014)
[3] (GRE Alpha Electronics Ltd., 2017)
[4] (Bluetooth SIG Inc., 2017)
[5] (GRE Alpha Electronics Ltd., 2017)
Digital addressable lighting interface, or DALI, is a global standard that enables ballasts, controllers, switches and sensors to communicate with other DALI-compliant devices. DALI was initiated in the late 90’s, but has since undergone drastic changes that expand its scope and improve its effectiveness.
Failing to recognize and comply with DALI 2 can impact your brand in a big way: you could lose your official DALI seal of approval. While your product could still function properly, lacking this seal can hurt your brand’s reputation and dissuade sellers. This makes knowing the difference between DALI and DALI 2 essential to your brand.
The primary focus of DALI has always been to ease the installation and use of ballasts and relay switches that enable dimmable, customizable lighting. The first iteration of DALI helped accomplish this by pushing for the standardization of system components and control gear. Some of the control gear functionality covered includes:
The second version of DALI, or DALI 2, improves upon the first iteration by now including the standardization of control devices. Some of these include:
An additional change brought on by DALI 2 is the increased scaling of DALI applications, such as the standards of automated building. Thus far this has resulted in better interoperability between DALI compliant devices, and increased the number of backwards compatible devices. This brings with it several major benefits.
Beyond the clear benefit of better interoperability, the invention of the DALI standard has resulted in numerous benefits to the LED and lighting world.
DALI standards have led to DALI dimmers, such as the SLD-DIM DALI and GLD DIM modules from GRE Alpha. These modules enable both new and old LED fixtures to become dimmable, without the added fuss of complicated wiring and circuitry this functionality would have required in the past.
Before DALI, ballasts were capable of one-way transmitting of information only. With DALI compliant ballasts, information can be sent to and from the ballast to the fixture. This enables the collection of error logs, custom programming of ballasts, and allows dimming based on brightness perception. Combined with the ballasts’ ability to limit the energy consumption only to what is needed, this means more precise and efficient lighting.
The rise of DALI has led to more LED manufacturers creating DALI-compliant accessories. This makes finding the perfect lighting solution easier for designers, as the DALI seal of approval ensures the part will work properly with their existing DALI-compliant devices. For example, architectural LED power supplies allow lighting to perform in collaboration with the structural design. This is made possible because DALI ensures DALI-compliant devices will work together.
Note: DALI compatible devices are not the same as DALI compliant. DALI compatible devices were built with the DALI standards in mind, but were not put through the same testing as DALI compliant devices. DALI compatible may work with DALI compliant devices, but their compatibility is not guaranteed. Look for the DALI seal to be on the safe side.
DALI-compliant devices may come at a higher cost than non-DALI-compliant devices. However, DALI devices often require less wiring than non-DALI-compliant devices, making them both cost efficient and easier to install. When looking at the price of DALI devices, keep this in mind.
The rise of DALI-compliant products, especially ballasts, has led to a bigger focus on products that perform better. With ballasts becoming more efficient and ensuring only the necessary power is drawn to power a fixture, LED power supply manufacturers have shifted their focus to making more efficient power supplies. There is no need to sacrifice quality for efficiency. Devices that are up to 97 percent efficient and reduce the end users exposure to flicker.
Despite the development of newer wireless control technologies such as Zigbee and Bluetooth LE the DALI protocol’s overhauled makes it relevant for years to come. In fact, the standard has been restructured and now shows improvements in speed reliability. Combined with modern LEDs, the standard has led to more efficient and adaptable lighting, yet a lack of understanding has led to many companies not moving forward with DALI-compliant devices. Become acquainted with the benefits of DALI, and then contact GRE Alpha for more information on our easy-to-install DALI-compliant dimming modules.
For info on changes and updates to the DALI technology check out our latest article here.
If you have attended a trade show recently, the buzz surrounding LEDs and the incorporation into luminaire design is inescapable. Previous generations of LED luminaires attempted to incorporate LEDs into essentially the same design as their traditional counter parts. This limited both performance and possibilities. As the demand for energy efficient lighting increases integrating LEDs into design becomes less of an afterthought. LED luminaire design is very different from traditional fixture development. LED luminaire design requires a systematical approach that balances competing requirements such as:
LED lighting is known for its efficiency but even the most efficient light sources would be judged inadequate without high-quality optics. A compact fluorescent lamp, for example, can lose up to 70 percent of its light if paired with an inappropriate optic, says Nadarajah Narendran, director of research at the Lighting Research Center (LRC), in Troy, N.Y. Likewise, the touted efficacy of LEDs wouldn’t exist without the right optics. (archlighting.com) As efficiency and thermal performance in LED packages continue to improve, they pose design advantages. Fewer LEDs may be needed to satisfy light levels and optical distributions. This allows even greater flexibility in optical and mechanical design. This empowers lighting manufacturers to create lighting solutions tailored to meet the most demanding field requirements and yield maximum supply chain value.
While luminaire designers are making tremendous leaps using technology, there are some practical considerations to keep in mind. Supplying power to these innovative light sources requires specialized LED drivers. LEDs are designed to run on low voltage (12-24V), direct current electricity. Conversely, the most common power supply is at a higher voltage (120-277V) using alternating current electricity. An LED driver rectifies this problem. Secondly, protection from voltage or current fluctuations come into play.
Too much or too little current can cause light output to vary or degrade faster due to higher temperatures within the LED.
Heat dissipation is and has been one of the primary challenges with LED technology. LED junction temperature must be kept below manufacturer specified levels to achieve long life. Luminaires with smaller form factors tend to have poorer thermal performance. This can lead to compromises such as a lowering the intensity of the light or sacrificing some longevity in favor of intensity.
Updated energy codes require efficient, bilevel lighting. This tips the scale toward units that low in power and often offered with 0-10V dimming control standards. Greater energy savings are achieved through occupancy and daylight dimming controls. As digital light sources, LED lighting fixtures can be precisely controlled with dimmers, push-button devices, wireless touchscreens, smart phones or integrated into a structure’s IT system. Digital Multiplex (DMX) and Digital Addressable Lighting Interface (DALI) protocols have become widely adopted. While the initial priority focused on making commercial lighting more controllable, popularity has increased and it is now used in various applications, including hotel, restaurant, and residential settings.
GRE Alpha has a wide array of products that elevate luminaire design.
The GRE Alpha XLD 75 and XLD 200 both offer dual modes, giving you constant current and constant voltage options. Furthermore, both the output current and voltage are adjustable, letting you get the most optimal performance from your light fixtures. And as the only UL listed LED drivers on the market, you can use them to drastically reduce your approval times and agency approval costs.
Both of these models are easy to install thanks to our patented enclosures, which simplify wiring requirements. Fast to install and capable of working in temperatures ranging from - 40°C to -60°C, both options will have users remotely controlling their lighting in no time, no matter the environment.
The DALI Dimming Module and SLD-DIMTW Tunable White Dimming Module give users even more advanced customization and control of their lighting. Both capable of being incorporated into your existing LED drivers, these solutions offer customization with an extremely small form factor, high efficiency, and competitive cost. Easy to install and inexpensive, this simple upgrade can be implemented on new lighting projects, or retrofit to your older fixtures, enabling them to support industry standards like 0-10V, DALI, DMX, TRIAC, wireless and more.
GRE Alpha is committed to innovation and to delivering high-quality, leading edge LED lighting solutions. For more information about LED drivers, dimming modules, and accessories, or to speak with a GRE Alpha product expert, visit the Enquiries page and fill out the Enquiry Form. Sign up for the GRE Alpha newsletter to stay up-to-date on new products and for early access to other GRE Alpha news.