User's Manual

10 Introduction
The Echelon Street Lighting Solution
Energy and maintenance costs are increasing for municipal street lighting.
Recent studies show that the electricity used for street lighting can account for
up to 40% of municipal electric bills. With an estimated 90 million street lights
in Europe and 63 million in North America, efficient use of energy for street
lighting is important, both for economic reasons and for environmental reasons.
Fortunately, components and systems are now available to manage, monitor, and
reduce that electricity demand.
Such a system incorporates several key elements: electronic ballasts, power line
communications hardware, and local network controllers that are interconnected
with specialized control and reporting software. Together, they create a flexible
and powerful control system that simplifies day-to-day operations and facilitates
the implementation of cost-cutting strategies. Establishing two-way
communications with each lighting fixture in a street lighting network allows you
to control the lighting level of each fixture, turn it on and off, and monitor its
condition.
Because each luminaire in a street lighting network is already connected to the
power grid, defining a power line communications channel for the network is a
straightforward way to establish two-way communications with each lighting
fixture. However, in many countries, there are a limited number of luminaires
per low-voltage service distribution transformer, and, in general, a power line
channel cannot maintain communications across a transformer.
Echelon introduces the Echelon
Street Light Bridge module : a power line and
wireless hybrid device that allows communications to bridge the low-voltage
service distribution transformers, and manage an extended street lighting
network.
Figure 1 on page 11 shows part of a basic street lighting network, with a
SmartServer Segment Controller, several street lights, a service distribution
transformer, and a pair of Street Light Bridge Modules. The Segment Controller
uses power line communications to communicate with the street light luminaires
and the Street Light Bridge modules. The Street Light Bridge modules use radio
frequency communications to communicate with each other, and thus provide a
communications bridge across the service distribution transformer.