Introduction

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Volume 7 Issue 4	June 2003

ballast - A device required by electric-discharge light sources such as fluorescent or HID lamps to regulate voltage and current supplied to the lamp during start and throughout operation. ballast factor (BF) - The ratio of the light output of a fluorescent lamp or lamps operated on a ballast to the light output of the lamp(s) operated on a standard (reference) ballast. Ballast factor depends on both the ballast and the lamp type; a single ballast can have several ballast factors depending on lamp type. compact fluorescent lamp (CFL) - A family of single-ended fluorescent-discharge light sources with small-diameter [16-millimeter (5/8-inch) or less] tubes. electrodes - The structure that serves as the electric terminals at each end of electric discharge lamps. high-intensity discharge (HID) - An electric lamp that produces light directly from an arc discharge under high pressure. Metal halide, high-pressure sodium, and mercury vapor are types of HID lamps. luminaire - A complete lighting unit consisting of a lamp or lamps and the parts designed to distribute the light, to position and protect the lamp(s), and to connect the lamp(s) to the power supply. (Also referred to as fixture.) load shedding - The practice of turning off electrical devices during peak energy demand hours to reduce building energy use. rated lamp life - The number of hours at which half of a group of product samples fail. The rated life is a median value of life expectancy; any lamp or group of lamps may vary from the published rated life. Rated life is based on standard test conditions. rated light output - The sum of the initial rated lamp lumens of the lamp(s) that were supplied with the luminaire.

Abstract

Lighting Answers: Adaptable Ballasts discusses a class of electronic ballasts that are compatible with multiple lamp types, different quantities of lamps, and/or different input voltages. The report explains the variety of adaptable ballasts available, examines their strengths and weaknesses, describes how a sample performed in independent tests, and suggests suitable applications for this new technology.

In 2001, sales of electronic ballasts for fluorescent lighting systems surpassed magnetic ballast sales for the first time, completing a full market penetration in just over a decade (US Bureau of the Census, 2001). Now, ballast technology is moving into its next evolutionary phase, incorporating advanced electronic circuitry to add functionality and flexibility. Among the new technologies available are ballasts that can dim lamps to 5% of full light output and run on the same dimmers as incandescent lamps, so-called "digital ballasts" that can be connected to networks and controlled individually or in groups using computers, and “adaptable ballasts" that can be used with different quantities or types of lamps, or can be operated on different line voltages. Adaptable ballasts offer the potential for greatly simplified stocking and ordering of replacement ballasts. For example, if a facility has three types of luminaires, such as a 120-volt 2-lamp fluorescent system, a 277-volt 2-lamp fluorescent system, and a 277-volt 4-lamp fluorescent system, it may be possible to keep one ballast model on hand that will work for all luminaires in the building.

Lighting Answers: Adaptable Ballasts explains the variety of adaptable ballasts available, examines their strengths and weaknesses, describes how they performed in independent tests, and suggests suitable applications for this new technology.