Police dispatchers and patrol offcers in
squad cars receive GPS data pinpointing
the location and a recording of the sounds.
to the scene
When a shot is fred, the sound
is picked up by sensors that
triangulate the origin of the noise.
26 NOVEMBER/DECEMBER 2015
conference | STREET & AREA LIGHTING
automatically summon police and provide a
precise location of shots.
We will discuss using internal meters in
street lights to determine billable energy a
bit more, but Fitzmaurice did comment on it,
saying that with LEDs and controls “you may
save energy, but you won’t save money” if you
stick with dusk-to-dawn energy-use tariffs.
And the final application area in the list
received special emphasis from Fitzmaurice
and Wilbur. Fitzmaurice compared the situation to installing a printer on a PC before
and after the advent of plug-and-play technology. He said plug-and-play technology
with street lights eliminates errors and lets
the line crews do what they do best — install
lights rather than use a tablet or smartphone
to record data and perhaps take a photo of
the installed luminaire. He said commissioning takes longer than installation. Georgia Power is using integrated GPS capabilities and three codes stored in the luminaire
at manufacturing to allow its central management system (CMS) to know everything
required about a newly installed luminaire
and to commission it automatically. Note
that GE has been touting the GPS feature in
recent case studies ( http://bit.ly/1DYT3GK).
Fitzmaurice said Georgia Power has
installed 500,000 LED fixtures over the last
four years. The company uses a mix of star-and mesh-topology wireless networks and
DALI (digital addressable lighting inter-face)-compatible drivers integrated in the
luminaires. The aforementioned codes are
stored in the driver. Upon power-up, the network controller reads the GPS, reads the three
codes, and transmits that data to the CMS.
Metering street lights for billing
Andrew Bloomfield, director of business
development at Enersource Power Services,
dug deeper into the concept of metering
integrated into luminaires. Enersource
Corp. is a municipally-owned utility that
serves the community of Mississauga,
ON, Canada near Toronto, and Enersource
Power Services is a subsidiary that specializes in street-light design and installation
for municipal and commercial customers.
Moreover, Mississauga was one of the first
North American municipalities to contemplate a complete conversion to SSL back in
2011 ( http://bit.ly/1XBBJNy).
Bloomfield, who is also vice chair of the
IES roadway lighting committee, said when
the 50,000-light project was planned the
municipality made a bold decision to install
controls. The primary mission at the time
was not metering the energy used by each
light, but that capability was a side thought
in the planning. The metering idea met
immediate resistance, however, and took
time and personnel changes before all of the
stakeholders agreed to evaluate the poten-
tial of metering.
The old method of billing for street lights,
according to Bloomfield, is based on a calculation involving the wattage of the lamps
and the ballast factor applied to a projected
load curve (on/off times) that varies by
month of the year. Tongue in cheek, he said,
“The methodology lacks precision.”
Precision and promises
The Mississauga lights can report voltage
and current level, and power factor over
time — everything needed for accurate bill-
ing, according to Bloomfield. But he added,
“Regulatory has not been as fast moving as
technology.” Regulatory opposition to inte-
grated metering has been based on a red her-
ring, according to Bloomfield — the idea
that such meters are not accurate. He coun-
tered, “Why are we using such an imprecise
system to measure street lights when we
could use a much more precise system?”
throughout the system to check the accuracy
of the luminaire meters (within a particular
tolerance, noted in the following paragraph).
The revenue-grade meters are rated at
±0.5% accuracy while the luminaire meters
are rated at ±2% accuracy. But Bloomfield
said the results have been largely correlated.
He said you can add a 5–6% premium on the
metered energy to cover other energy use in
the network, including the energy used by
the meters themselves, and derive a square
deal for all stakeholders. Furthermore, he
said with 85% of the planned installation
complete, the municipality is paying for a
3-M W load as opposed to a 9-M W load.
Of course, negotiation of an LED-centric
tariff could have delivered some savings as
well, but now Mississauga’s bills are accurate. Moreover, there are subtle savings
enabled by the metering. The old and new
load curves in Fig. 3 show that under the
unmetered scenario the municipality was
FIG. 2. GE Lighting will offer ShotSpotter technology for installation with networked
street lights, enabling triangulation of gunshots and automatic notification of police
for high crime areas.