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Correcting 0-10V LED dimming with digital drivers

Correcting 0-10V LED dimming with digital drivers

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By eeNews Europe



The design of dimming electronics has evolved, and many earlier LED luminaires are not compatible with conventional dimmers. What’s more, traditional switch-mode power supply controllers don’t work with most LED ballast installations. Running low-voltage control wire to every luminaire to circumvent the problem is not cost-effective and can create even bigger issues with LED retrofit projects. There needs to be a more elegant, universal solution to control LED dimming systems.

The 0-10V convention for luminaire dimming is widely accepted by the lighting industry, and LED drivers usually come with a firmware upgrade to accommodate 0-10V dimming. Unfortunately, these dimming instructions are unidirectional, and one-way communications does not offer any indication if the luminaire has dimmed or even is dimmed to the appropriate lumen output level. There is no way to determine if the light levels are visibly correct or the energy consumption has been reduced.

Retrofits are increasingly popular for reducing
energy usage.

To overcome these challenges, intelligent microprocessors are being integrated into LED drivers to provide digital dimming control. With programmable controls, which can sometimes include two-way communications, you can reduce installation costs and use software for rezoning luminaires and reprogramming to ensure consistent light output and quality, even among multiple manufacturers. However, even with digital dimming controls you still need to compensate for driver variables via software.


Understanding variations in 0-10V dimming

Since there is no standard for 0-10V LED dimming, each manufacturer has its own dimming curve for their luminaires. For one vendor, a 5V signal could indicate dimming to 50 percent of initial output, while for another vendor 5V could translate to 30 percent or even 80 percent output. There is no consistency and the only way to ensure uniform lighting is by reprogramming the dimming curves in the luminaires using digital drivers.

Also, with no 0-10V dimming standard you are never really sure if a luminaire is truly “off” at 0V. For example, is the dimming curve truly 0-10V or is it really 1-10V. Some drivers are set to dim only to 1V, which is 10 percent, so the luminaire may be perceived to be off when it is still using power. Some of these types of drivers may even require a separate relay for off, i.e. 0V. Without digital drivers and luminaire monitoring you may never know if you are wasting energy.

Ideally, you also want centralized control over individual luminaires and zones so you don’t have to configure each luminaire manually. To control various zones you could install low-voltage control wiring, but requires wiring every luminaire driver in the zone, and you would still have to adjust lighting panels, occupancy sensors, photocells, and time clocks manually. Even with a well-designed low-voltage control system you can still miswire or mislabel a connection, creating headaches for you and for the next building tenant. What’s more, any simple change in the lighting layout means ripping and replacing this control wiring, which is messy and disruptive. Control wires are not economical or practical.

There also is no standard for 0-10V dimmers either, so one manufacturer’s dimmer may not work with another vendor’s drivers. If the luminaire flickers or fails then the dimmer or driver will have to be replaced. If you are using a variety of manufacturers’ drivers and LED lamps, then you risk having lights pop on or off or darken completely when dimmed, or they could flicker or strobe when turned on or off. Compatibility is not guaranteed.


Programmable drivers deliver uniformity

Software and an intelligent LED driver
can enable customized programming of a dimming curve.

With digital LED drivers all the settings, including dimming, can be software controlled. The driver hardware has on-board intelligence as well as programmability so luminaires can be grouped and programmed, then regrouped and reprogrammed to accommodate updates and changes without disruption. This configuration also enables complex zoning, which can improve functionality and energy savings.

Fulham’s intelligent driver with handheld programmer
for field or production line programming.

Digital LED drivers can be programmed at the factory, at the warehouse, or on-site. Using handheld devices, luminaires can be configured to ensure that luminaire brightness, hue, and other characteristics match the other luminaires either installed or being added, as well as programming dimming profiles for uniformity. To simplify installation and software updates it makes more sense to connect luminaires into a single, centrally managed infrastructure.

Rather than worrying about control wiring, the new generation of LED drivers are equipped with wireless options that enable two-way communications for dimming and other controls. Bluetooth

Bluetooth mesh is a standard way to interconnect
lighting elements.

mesh, for example, is becoming increasingly popular with luminaire manufacturers because it is an open standard and easily scalable. Since the wireless mesh structure is based on Bluetooth, wireless driver compatibility can be assured and the broadcast mesh infrastructure is scalable and allows you to add or remove devices without disruption. Once it is connected, the entire luminaire ecosystem can be managed by software from a central dashboard to ensure consistent luminaire performance, including 0-10V dimming.


Two-way communications also ensures that luminaires perform as expected. Monitoring across the ecosystem provides information about luminaire characteristics, as well as the performance of other components in the system such as switches, panels, dimmers, and sensors. Remote diagnostics and maintenance often can be performed remotely using software commands sent over a wireless link. And by using open standards such as Bluetooth mesh for communications users aren’t locked into only one manufacturer’s proprietary system – no more limited programming options or expensive service contracts.

Digital LED dimming systems can be integrated into building management systems as well. Lighting is the most prevalent electrical system in any building and the same programmable LED drivers can be equipped with sensors to detect temperature, ambient light, and more. The two-way intelligent lighting control infrastructure can be extended to manage HVAC and other building systems. Automating building management could result in an additional 40 percent energy savings in addition to the energy savings from an LED retrofit. More advanced systems can even use the smart lighting infrastructure to track hardware using Bluetooth tagging, or to support for wayfinding, safety and security, and even quality control using various types of wireless beacons.

The first step, however, has to be intelligent digital drivers. With digital programmability, LED drivers can be configured to delivery consistent dimming characteristics, and by adding wireless connectivity you add an entire new dimension of capabilities and control.

 

About the author:

Russ Sharer is Vice President of Global Marketing and Business Development for Fulham – www.fulham.com – He can be reached at rsharer@fulham.com

 

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