just as a heart adjusts to conditions –– sleep, exercise, stress, or relaxation –– an electronic ballast can adjust to the conditions imposed on it. As mentioned in the definition provided above, some ballasts can specifically vary the light output of your fluorescent or HID lamps for the purposes of dimming.
Modern 400 watt metal halide ballastincorporate many features that result in incredible economic savings, along with environmental benefits and easier compliance with increasingly rigid power reduction codes and energy efficiency requirements.
Paired with the right controls, a dimmable ballast can give you the option to smoothly vary light output based on the conditions. One practical application for this solution is meeting.
400 watt metal halide ballast factor is calculated by dividing the lumen output of a lamp-ballast combination by the lumen output of the same lamp(s) on a reference ballast. A ballast factor of <1 means that your fluorescent system will produce less light (lumens) than the reference ballast and a factor of >1 means it will produce more light.
Unlike hearts, HID ballasts can also operate dually –– with two or more separate ballasts working together to regulate the light output of multi-lamp fixtures. This solution is a budget and installation-friendly option if you need to simply switch 50 percent of the lamps off within a single fixture.