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Appendix A: AMX Lighting Curves
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RE-DM4 and RE-DM6 RADIA Eclipse Dimmer Modules
Appendix A: AMX Lighting Curves
Overview
Thousands of different lighting fixtures with unique shapes and styles exist, all designed to do something
visibly different with light. Any one of those fixtures in a hundred different locations could produce a
different lighting effect. Two identical lights in different locations could produce different reflections and
shadows.
For instance, consider a situation where low-voltage track lights are mixed with compact fluorescent
down lights to illuminate a hallway with pictures. Under normal dimming conditions, the two different
light sources would dim differently and possibly require individually set dimmers to accomplish uniform
lighting at different levels. An Up or Down button on a wall control panel would dim both sources at a
common rate, but the lamps and fixtures would dim at different rates due to the lamp and ballast
characteristics. The track light may stay bright for an extended period and then rapidly dim to nothing
while the fluorescent lamp dims smoothly to a point and then abruptly shuts off. The combined effect
produces an uncoordinated scene change.
An unwanted feature of dimmable fluorescent ballasts and low-voltage electronic transformers is their
tendency to cause the lamps to flicker when dimmed to low levels. The normal way to avoid this is to use
presets that are not dimmed below the fixture's threshold or to use any low end trim feature provided by
the ballast or transformer manufacturer. Problems arise when the performance of the dimmer does not
match the performance of the dimmable ballast. The AMX Lighting system now gives the user the
ability to change the performance of the dimmer to avoid problems.
Many types of track lights and dimmable ballast only have a limited dimming range for the dimmer to
work with. In a dimming range of 0 to 120 volts AC, many lamps do not start to dim until fewer than 100
volts is applied. Lamps often do most of their dimming between 40 and 100 volts. Dimmers designed to
increment voltages from 0 to 120 volts can be wasted on lamps that do not even respond to 50% of the
dimmer's output. Some lamps are more sensitive to voltage changes at the low end and can accommodate
many degrees of dimming, but standard dimmers tend to rush past the lamp's sensitive range and
occasionally linger in an unusable range.
Slowly turning a lamp on can be a very different effect than slowly dimming that same lamp off. Some
light sources require a minimum level to turn on. Once these lamps are on, they can be dimmed down to
lower light levels. At the same time, most common dimmers are built to dim at a uniform rate, regardless
of the individual characteristics of each lamp or the number of lamps.
The properties and dimming characteristics of each new lamp and ballast on the market present a new
challenge to the dimmer manufacturer to provide an appropriate dimmer. What was designed as a
standard incandescent dimmer must now be able to control electronic ballasts, incandescent lamps,
transformered low-voltage track lighting, and a host of electronic transformers.
One way to solve many of these problems is to tailor the style of dimming for each individual dimmer in
a system. The way to do this is to apply different dimming curves to each dimmer and to provide a
variable low-end cut-off point.
A dimming curve is a graphical or electronic representation of the amount of control to a dimmer in
relation to the dimmer output. It is like a directional map followed by the dimmer. The amount of control
is typically measured in percentages, from an off-state at level 0 to an on-state at level 100. Dimmer
output is measured in volts. A graphical representation of a dimming curve is usually the percentage of
dimming in relation to the output voltage (RMS) of the dimmer connected to a standard load.
AMX Lighting curve changes are implemented by a command to the AMX Lighting device. This
example would set dimmer channel #1 to curve 6. The available curves that can be sent to the AMX
Lighting controller are: 1, 2, 3, 4, 5, 6, 7, 8, 9, A, B, C, D, E, N, O, R, and F.