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The lighting market in
commercial buildings is primarily static (non-dimming)
fluorescent lighting fixtures. Dimming ballasts are
available, but due to current market conditions and
high costs, are only 3 percent of the total ballast
market.
One
barrier to the increased use of dimming ballasts is
the lack of a dimming ballast controller appropriate
for installation in existing buildings. Such a controller
is the prime target for development in this project.
To maximize the penetration of dimming controllers into
the market, they must be easy to retrofit into existing
buildings. This means it should be possible to install
the new system without requiring new power circuit wiring
or additional low-voltage control wiring. The power
line carrier controller developed in this project will
bridge this critical gap by allowing control of connected
ballasts using the in-place power circuit switch-leg
wiring as the communications medium.
A
second feature of the dimming market is the availability
of "inline controlled" dimming ballasts, which can be
dimmed directly over the in-place switch circuits without
additional control wire. The controller developed in
this project targets these specific ballast types for
control since they are most appropriate for installation
in existing buildings where any additional wiring costs
are economically unacceptable.
One
concern over the use of "inline controlled' dimming
ballasts is the potential of increased current harmonics
as the lighting system dims. Under extreme conditions,
these additional harmonics may cause interference with
building electrical equipment.
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Project
Information for Retrofit Fluorescent Dimming with
Integrated Lighting Controls
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Two
features of the lighting controller in this project
directly address these market barriers. First, the lighting
controller will include a back-end circuit that mitigates
the harmonics produced by the controller/ballast system.
Secondly, the prototype lighting controller will incorporate
a "firewall" that will contain most of the residual
harmonic distortion in the controlled lighting circuit.
By containing any harmonic distortion to the load-side
of the controller, no other building equipment on the
"line-side" should be affected. In other words, any
residual harmonics will not be able to cross the controller
and cause interference with building equipment.
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