What is a ballast?


Let’s talk about ballast. What does a ballast do? It has two main functions. It starts the lamp and it controls lamp operation. All gas discharge lamps: linear fluorescent, compact fluorescent, and HID require a ballast. Now there’s basically two types of fluorescent ballasts. There’s an electronic ballast and there’s a magnetic ballast. So here you see the T12 magnetic and T8 electronic. The T12 magnetic has gone away. You can’t buy it nor manufacture it in the United States and that’s because this system here is about 58 lumens per watt while the T8 system down here is 98 lumens per watt. We had to upgrade it to the new fluorescent systems because they’re more energy-efficient. Fluorescent electronic ballasts come in three types. Instant start. The lamp comes on very fast and when you have one lamp fail, the other stays lighted. The second type is program start and that takes a little bit of delay because the lamp electrodes have to heat up to 700 degrees Celsius. This is a great system for occupancy sensors, but when one lamp goes out so does the other lamp. New to the field is parallel program start. Again, that little bit of a delay to start to heat up the electrodes, but when one lamp goes out the other one stays lighted. Parallel program start is recommended for use with occupancy sensors. All of these T8 electronic ballasts are intel evolved. That means that they will operate 120 through 277, so 120 to await 240 or 277 voltage. These ballasts will also operate a 32 watt lamp a 30 watt energy saving lamp, 28 watt and 25 watt energy-saving lamps, the F25 3 foot lamp, the F17 2 foot lamp, and the U-Bend lamps. T8 electronic ballasts have a ballast factor. The ballast factor is a multiplier. It tells us what percentage of the light produced in the laboratory will be produced by a particular lamp and ballast system. It allows us to deliver the appropriate light level into the space for the least amount of watts. The charge you see on the screen, shows how different ballast factors affect both the light output and the wattage consumed. HID ballast. HID ballast comes in electronic and magnetic form. This is a magnetic HID ballast, a core, iron core and a copper coil. The capacitor helps to convert Volts and Amps into Watts or power more efficiently and the igniter in a pulse start system helps to start the lamp. The wires you see here are actually the various voltages that the ballast could be hooked up to. This one can be hooked up to 120, 208, 240, or 277 volt depending on which one is serving the facility. HID magnetic ballast are married to a particular lamp. This is a 400 watt courts probe start metal halide married to an M59 magnetic ballast. M for metal halide, 59 for 400 watt. The capacitor helps to convert volts and amps into watts or power. The middle one here is an M135. It is firing a pulse start 400 watt metal halide. So M for metal halide, 135 for 400 watt pulse start lamp. This is an external capacitor and an external igniter that’s used in a pulse start system. And this is the last one, a M143 metal halide pulse start ballast, where the igniter and the capacitor are inside the ballast. This drives a seventy watt ceramic discharge metal halide lamp.

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