Smart cities demand smarter systems integration. If we are to build a variety of community and citizen services upon an internet of things (IoT) infrastructure deployed initially for outdoor lighting control, the network will require a level of reliability beyond historical control system functionality that cause lights to go on, off and dim.

A new way of thinking about controls is needed, where lighting control is one of multiple functions enabled by communication between luminaires. This requires greater integration of power and communications, driver and wireless radio technologies.

On one level, integrating an LED driver and wireless radio seems to be a simple step forward. Reducing the number of pieces of hardware will simplify installation and maintenance, reducing the overall control network cost over its lifetime. It is much simpler to connect mains power to one rather than two devices when installing the system. It is also true that the simplest solution is usually the best one.

However, before reviewing the value of integrating LED drivers to power smart street lighting we should first consider the implications of smart street lights as a framework for smarter cities.

IoT – a wireframe for smarter cities

IoT promises to address a variety of device monitoring and management issues beyond smart street lights. However, before we rush into delivering total connectivity, we have to consider real-world economics.

The IoT has to overcome market challenges to make it viable as the common framework for smart cities. This is especially true when you consider the lighting industry, which has a mature supply and deployment strategy with heavy emphasis on keeping prices down.

Dumb luck

Ironically, the dumb, cheap lights installed today that do not have the IoT communications needed for smart lighting will have a useful life of at least 10 years. That will delay IoT for smart lighting by a decade or more, even though lighting provides the perfect IoT skeleton for smart cities.
Light is everywhere, and it is often one of the first things added by municipalities to promote public safety. When you consider the possibilities of combining street lights with smart LEDs powered by integrated drivers, additional possibilities open up to promote public safety and save energy.

For example, using the IoT to centralise control of street lights and webcams can aid law enforcement and crowd control. Since streetlights are installed at regularly spaced intervals they can be used to monitor air quality or precipitation, for example, as well as lighting.
Smart lighting also provides device monitoring for fault management. For example, when servicing a street lamp it will save money if the cherry‑picker is used only once, since the engineer will already know which parts are needed.

It all starts with a common connected infrastructure using an open protocol such as the IoT. Using street lights as a skeleton for automating the management of city services needs common communications protocols for interoperability. Unfortunately, lighting is late to the game when it comes to IoT and manufacturers are using other industry standards for light management and communications.

For example, the digital addressable lighting interface (DALI) is the most widely used wired standard for digital lighting controls. Created by Philips in 1964, DALI has evolved into IEC standards and is a common interface for conventional lighting controls and interoperability.

However, DALI applies only to lighting and does not interoperate with the IoT. Similarly, ZigBee is a low-power wireless standard used for applications such as lighting controls, but ZigBee competes with Wi-Fi, Bluetooth Mesh, and other wireless standards for the IoT.

City managers will look for platforms that provide interoperability beyond lighting, using the IoT as a common protocol to provide control information to different types of devices such as traffic signals, manholes and waste receptacles.

The most likely scenario is that wireless communications and the IoT will be used as the common platform for management and control, and data will aggregate in the cloud for access by a central control console. Using secure cloud storage for data will make it easier to access by city departments and service providers, and it will provide a central data repository for applications such as big data.

The reasons outlined below demonstrate that integrating drivers and wireless controls offers significant advantages over previous solutions in terms of simplicity, reliability and energy efficiency.

Four arguments for integrated LED controls

At Fulham, as we worked through the challenges of delivering a smart lighting system as part of centralised smart cities solution, we recognised that there are at least four reasons why integrating controls into LED drivers makes sense.

1 Integrating the right controls system

Wireless systems are suitable for street and municipality lighting, since outdoors in free space radios can work free of interference. However, selecting a medium was only the first step – engineers are now faced with which wireless system to use.

Minimising the cost of on-site equipment rapidly became a top priority. For too long controls have been plagued with what is known as the “£10,000 box problem” – the requirement that a system has an expensive computer and/or gateway device on site with the lighting network.
This burdens the system with higher start-up costs, the need for a secure, controlled location in which to place it and specialised power protection to ensure its continued operation.

In addition, the hardware, usually a server, must be kept up to date.

A cloud-based control system where only a small, relatively inexpensive gateway is required as the bridge between lighting control network and a remote monitoring centre will, over time, assist IoT networks to scale and grow more efficiently as additional capacity can be added quickly and inexpensively.

2 Reliability improvements: element protection

With the expectation that outdoor lighting control networks will be the infrastructure of budding IoT networks, we wanted an architecture that offered the maximum protection for the wireless control, especially from weather and vandalism.

By integrating the control module into the driver, the luminaire provides protection for all key components – light source, driver and controls.

Outdoor luminaires are designed to meet strict International Protection standards, so integration provides all of the solution components with better protection.

3 Reliability improvements: driver health

With LED light sources now offering levels of reliability that are unachievable for incandescent, induction or fluorescent light sources, any luminaire problems are more likely to be tracked back to the driver.

By integrating the control element into the driver, as with, for example, Fulham’s WorkHorse LED outdoor driver – which has integrated Tvilight controls – built-in diagnostic reporting through the wireless interface became possible. This offers far more diagnostic capability than is available through a standard 0V to 10V dimming interface.

Operating hours, operating temperatures, performance characteristics and configurations are just some of the data that can be read from a remote monitoring centre.

Using remote performance monitoring, replacement units can be automatically dispatched for deployment before a luminaire fails, and once it is installed, the driver’s commissioning can be completed via configuration download from the cloud.

This means a huge savings for outdoor lights, which typically require two round‑trips for each failure – one to troubleshoot and one to repair, especially since each repair requires an expensive cherry-picker. Reducing the replacement work to one trip saves valuable time and resources.

4 Efficiency improvements: lowest standby power

Usually one of the primary objectives of a lighting upgrade project is to reduce overall power use.

By integrating the wireless control module, drivers use lower standby power, waking first the wireless module then the driver. The company’s calculations show a power saving of 40% to 50% compared to a control interface connected through 0V to 10V, even when the interface does dim‑to‑off.

As new IoT applications are built, integrating LED driver and wireless controls will offer even more advantages.