Sources & Auxiliaries
Last Update: November 1, 2011
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Sources and Auxiliaries Overview

Energy-efficient electric lighting begins with the proper choice of light source for the luminaire and application involved. Usually, that means starting with a high-efficacy (lm/W) light source; but not always, as considerations of lighting quality or application requirements are factored into the design. The choice of light source is critical, however, since it affects every aspect of the lighting installation over its lifetime.

This chapter describes electric light sources from the technical and application standpoints so that they can be selected, evaluated and compared. The task is complicated not only because there are many thousands of individual light source products, but also because some light sources require auxiliary electrical equipment such as a ballast in the case of fluorescent and HID lamps and a driver in the case of LEDs and other SSL sources. Matching the light source to the ballast or driver is essential and that light source “system” may also have to be matched to the thermal characteristics of the luminaire and electrical characteristics of the lighting control or electrical supply system as well.

Electric lighting is now more than 125 years old. Practical incandescent lamps became available in the late 1800s and, over the following 30-50 years, substantially replaced candles, gas mantles and other flame sources. Fluorescent lamps were introduced in 1938 but did not become widely used until after World War II in the late 1940s. HID lamp technology grew out of the arc lamp technology of the early 1800s although mercury lamps did not become widely used until the late 1950s. Metal halide and high pressure sodium lamps were commercially introduced in the 1960s. The LED was invented in 1964, but because of low light output and limited color choices was used only for indicators and special applications. With efficacy and lumen output improvement as well as white light versions, however, LEDs are leading the transformation of light source technology and dramatic changes in general lighting applications.

Title: Examples of Light Sources for General Lighting.  Sources & Auxiliaries Figure 1.

Caption: Energy-efficient lighting starts with the light source and the transformation of electrical energy into visible energy: light. No single type of lamp is optimum for all situations. Consider the numerous choices carefully. Just a few of the available halogen incandescent, fluorescent and HID lamps are pictured here. Illustration courtesy of OSRAM SYLVANIA Inc. and Paul KevinPicone/PI Corp.
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Sources & Auxiliaries

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