METAL HALIDE BALLAST

James Lighting Commonly used probe-start metal halide ballasts(MH) systems for mid-wattage MH lamps include high-reactance autotransformer (HX-HPF), constant-wattage autotransformer (CWA), constant-wattage isolated transformer (CWI), and regulated lag (magnetically regulated) metal halide ballastsHigh-reactance autotransformer (HX-HPF): These metal halide ballasts are similar in performance to reactor ballasts (discussed below), but their additional coils allow them to start the lamp from supply voltages that are lower than those necessary to start the lamps. As a result, these metal halide ballasts are bigger, heavier, and less efficient than reactor ballasts, but they can be used in a wide variety of applications, because they come with multitap capability. A typical current crest factor (CCF) range for these metal halide ballasts is 1.4 to 1.6. Most HX-HPF metal halide ballasts are rated to handle supply voltage variations of 5 percent, which results in a 9 to 12 percent lamp power variation.Constant-wattage autotransformer (CWA): Also known as lead style metal halide ballasts, CWA metal halide ballasts are the most common ballasts used on 175 W or higher MH lamps. This type of metal halide ballast has a different design than the reactor and high-reactance autotransformer (HX-HPF) ballasts. CWA metal halide ballasts offer better lamp power regulation, but they are heavier, larger, less efficient, and more expensive than reactor or HX-HPF styles. Constant-wattage isolated transformer (CWI): This metal halide ballast is similar to CWA design, but has an electrical isolation between the primary and secondary windings.