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Following a major technological shift from mercury vapor to metal halide in the past decade or so, high-intensity discharge (HID) product innovation is focused on this source type, specifically pulse-start systems. The main drivers are energy efficiency, longer life and controllability among higher wattage lamps, and miniaturization and improved color performance among lower wattage lamps.
Pulse-start metal halide lamps offer a number of performance advantages compared to probe-start, including energy savings, higher light output and lumen maintenance, whiter light, faster ignition, and good lamp-to-lamp color consistency. Ceramic metal halide lamps are pulse-start lamps with a ceramic arc tube, which provides higher color rendering and greater color consistency both lamp to lamp and over time. This advantage presents a premium option for applications in which color is critical, such as retail.
Advanced service-life options are available for pulse-start metal halide and high-pressure sodium, satisfying owners interested in reducing maintenance costs while allowing these technologies to remain competitive with LED. High-pressure sodium options offer up to 40,000 hours and pulse-start up to 26,000 hours. Venture Lighting’s Super Long Life pulse-start metal halide lamp, for example, is rated at 40,000 hours using two independent arc tubes, one of which is working at any given time.
All <150-watt (W) metal halide systems are pulse-start, with miniaturization allowing wattages as small as 15W (e.g., Sylvania Metalarc Powerball)—an option that produces light output comparable to a 12-volt (V) 50W MR16 halogen lamp for about 60 percent less energy consumption. In recent years, some of these and higher wattage ceramic metal halide lamps have become able to render well-saturated reds commonly found in retail spaces (R9>40). Examples include EYE Lighting’s Cera Arc (39, 70, 150, 250 and 400W with 50–90 R9), Philips’ MasterColor CDM Elite (210 and 315W with R9>40), and Sylvania’s Metalarc Powerball (15, 20, 39, 70, 100, 150, 200, 250 and 320W).
Pulse-start can displace probe-start on a one-for-one basis for about 20 percent energy savings, or the higher light output can be leveraged toward fewer fixtures with associated capital and energy cost savings. In an existing installation, however, the ballast must be replaced because pulse-start lamps need a compatible pulse-start ballast. A notable exception is Philips’ Energy Advantage lamps with All Start technology, which are ceramic metal halide lamps that can operate on probe-start ballasts. The line recently expanded from 205W and 330W to include a 145W alternative to 175W and an 830W alternative to 1,000W. While this solution would be suitable for a number of applications, ballast replacement provides an opportunity to switch to an electronic ballast.
A well-designed electronic ballast operates at up to 95 percent efficiency compared to magnetic ballasts’ 88 percent efficiency. They also are smaller, lighter and provide higher lumen maintenance, longer life, fault-mode protection and better power regulation, resulting in better color consistency. Installation is simplified through an integrated product that incorporates the conventional elements of ballast, capacitor, ignitor and mounting brackets into a single unit. End-of-life protection shuts the lamp off to prevent cycling. The ability to drive a 120V quartz restrike lamp may be an option. Availability of dimmable electronic HID ballasts is expanding rapidly, covering wattages from 15W to 750W, both metal halide and high-pressure sodium systems, and with the ability to join 0–10V DC, DALI-based and proprietary control networks. Examples include Empower, GE UltraMax, Metrolight SmartHID Plus, Philips Dynavision and CosmoPolis and Sylvania Quicktronic.
Product regulations, energy codes and utility rebates are driving the overarching trend toward higher efficiency and controllability.
For example, the Energy Policy Act of 2005 eliminated the manufacture and import of mercury vapor ballasts in 2008, although later legislation allowed specialty ballasts. Legislation in Congress would eliminate mercury vapor lamps (as part of larger regulations for outdoor lighting); if Congress fails to act, the Department of Energy (DOE) is expected to produce its own rulemaking, with the ban expected to become effective in 2016.
The Energy Independence and Security Act of 2007 established energy standards for ballasts sold as part of new 150–500W metal halide fixtures, which eliminated a majority of probe-start ballasts from these products. California expanded these rules, encouraging electronic ballasts or the use of an occupancy or photosensor control. The DOE is currently working on a rulemaking that may expand wattages beyond this range, while tweaking efficiency levels higher as well as a rulemaking for metal halide lamps that appears aimed at eliminating probe-start lamps, effective in 2016.
Energy codes are also having a big effect on HID lighting, restricting power, while increasingly requiring bilevel lighting, with an associated boost for dimming. Utility rebates for pulse-start and ceramic pulse-start upgrades have increased.
As mercury vapor declines and pulse-start metal halide surges in innovation, building owners can benefit from HID sources that efficiently produce white light with long life, reducing costs while complying with energy regulations.
About The Author
DiLouie, L.C. is a journalist and educator specializing in the lighting industry. Learn more at ZINGinc.com and LightNOWblog.com.