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Replacing conventional street lighting with connected poles using energy-efficient LEDs is an effective way to reduce energy consumption and associated emissions. The City of Bradford in the U.K., for example, uses long-range wireless networks to control its LED smart streetlights. The city authorities estimate that the units reduce power consumption by 65 percent and associated carbon emissions by over 6,000 tonnes per year compared with traditional lighting[1]. With conventional street lighting consuming between 30 and 50 percent of the total electricity consumption of municipalities, such savings are significant contributors toward ‘zero carbon’ targets[2].
- Read more: How ‘smart poles’ can save energy and enhance smart cities of the future
- Read more: Smart lights bring cuts to carbon emissions
Moreover, The City of Bradford reports that smart streetlamps require significantly less maintenance, lasting around six times longer than the old low-pressure sodium lamps they replaced. But while the maintenance demand is reduced, there are still times when smart streetlights need fixing. Short-range radio technology such as Bluetooth LE is finding an application here too and is also making life safer and more convenient for the technicians tasked with looking after smart streetlighting.
Driving LED lighting
LED lighting is more complex than conventional illumination such as the low-pressure sodium lighting it has replaced. LEDs need to be powered using carefully controlled constant electrical currents and constant voltages if they are not to overheat and fail prematurely. The job is done by sophisticated power supply units called drivers. The drivers convert the incoming 240 V AC mains voltage to the carefully controlled low DC voltage needed to power the LEDs.
Today’s sophisticated drivers can do much more than just convert voltages; modern units are equipped with operating software and industry-standard technology such as the DALI2 protocol which enables bi-directional, digital communication between lighting-control devices. Such communication enables fine control between the driver and the LED for functionality such as phased dimming – reducing illumination at times when streets are rarely used and saving even more energy. Other functionality includes gradually increasing the operating voltage as the LED ages to maintain a given level of illumination.
Wireless tech improves convenience and safety
Smartphone-interoperable Bluetooth LE can be used to commission and configure new LED drivers and later carry out over-the-air (OTA) diagnostic and firmware updates. During maintenance, software bug fixes stored on the lighting technician’s mobile can be transmitted to the driver using low-power wireless connectivity with the driver in turn verifying the update and confirming back to the mobile over the bi-directional link.
Moreover, as driver technology improves over time—because engineers learn more about long-term LED performance and solid-state lighting operating parameters change as the LEDs become more efficient—wireless connectivity enables complete software updates. The performance of the installed driver can be upgraded by updating the software while leaving the original hardware in place – saving time and money.
The other significant advantage of wireless connectivity for driver maintenance is safety. OTA firmware updates allow technicians to fix or upgrade drivers without opening the smart streetlights and potentially exposing themselves to hazardous voltages.
LED driver uses Nordic Bluetooth LE
Nordic Semiconductor customer and telemetry and SCADA solution manufacturer, LACROIX Environment, has released an LED driver with Bluetooth LE connectivity. Called the PS-Pak, the product uses an Insight SiP ISP1507-AX module based on Nordic’s nRF52832 SoC.
The SoC’s Bluetooth LE wireless connectivity enables configuration of the PS-Pak from the associated iOS or Android app on a smartphone, without the need to access the interior of a high-voltage lighting unit. The wireless connectivity also enables over-the-air software updates. One PS-Pak can configure up to six LED drivers of the same light pole.
Smart streetlights hit the mainstream
Smart streetlights with LED illumination have hit the mainstream. According to analyst Research and Markets, the global installed base of individually controlled smart streetlights amounted to 23.0 million units at the end of 2022. That number is set to reach 63.8 million units by 2027[3] as conventional low-pressure sodium lamps are phased out and countries chase zero carbon targets.
Long-range wireless connectivity such as cellular IoT or DECT NR+ enables city-wide networking of the smart streetlights, but short-range connectivity is playing a key role too. Technology such as Bluetooth LE is making it simple for technicians to configure and update LED drivers while staying at a safe distance from high-voltage power supplies.
- Read more: Building high-density IoT networks with cellular IoT and DECT NR+
- Read more: Smart street lighting and cellular IoT is the gateway to the smart city
References:
1. https://www.bradford.gov.uk/transport-and-travel/highways/the-smart-street-lighting-project/
2. Streetlight Refurbishment with Energy Performance Contracting Guide, European Commission
3. The Global Smart Street Lighting Market, 2nd Edition, Research and Markets
