Public lighting systems play an essential role in protecting the safety of pedestrians and drivers in any major city. However, maintaining a city-wide network of street lamps requires a great deal of energy and financial costs. Moreover, leaving street lights on for too long negatively impacts the environment. As a result, street light control systems for public lighting networks have become a popular solution for municipal governments to reduce energy consumption and curtail expanding budget deficits. System functionality includes controlling a circuit of street lights and/or individual lights with specific ballasts and network operating protocols. Looking to reduce energy consumption, one of the largest cities in the European Union came to Moxa to help implement a cost-effective control system for its municipal lighting system.
• The city required a solution that is both easily scalable to accommodate future growth, and also able to reduce overall maintenance and energy costs.
• The solution must enable operators at the central control centre to not only turn the street lamps ON and OFF, but also to monitor weather conditions and climate changes.
• Provide reliable performance and secured connections for serial-interface programmable logic controllers (PLC) to control each municipal street light.
A programmable logic controller, or PLC, is connected to each lamp post to turn the street lamp ON and OFF. Since the PLCs used a serial interface, the city needed a way to control and monitor their entire system from a remote control centre. As cellular GSM/GPRS/EDGE networks already provide abundant coverage throughout Spain, Moxa decided to equip all the street lights with cellular connectivity to take advantage of the existing infrastructure in place. That way, the city not only saved money on additional wiring costs, but also saved on future maintenance. The OnCell G3150 connects Ethernet and serial devices over an integrated VPN. In addition, by connecting the PLC for each street light to an OnCell G3150 cellular IP gateway, computers at the control centre could easily monitor and control the city’s street lights over the Internet and optimize usage according to weather conditions.