Ballasts are power supplies or transformers for fluorescent lamps, light sources that consist of a glass tube filled with argon, neon, or other inert gas. When ballasts supply electrical current, the resulting arc emits ultraviolet (UV) radiation that excites the phosphors inside the lamp wall, causing them to radiate visible light.
Basic lighting ballasts can be as simple as a series of resistors – a common configuration in small neon lights. Other types of ballasts include electronic ballasts, magnetic ballasts, fluorescent ballasts, high intensity discharge (HID) ballasts, and metal halide ballasts. Ballast manufacturers are located across the United States and around the world. They adhere to a variety of standards, including guidelines from organizations such as the American National Standards Institute (ANSI).
Ballasts use several different technologies.
- Electronic ballasts use semiconductors to increase the frequency of fluorescent lamp operation, which is typically in the 20 – 40 kHz range. Typically, electronic ballasts are used in fluorescent lamps that produce fixed lighting or use a dimmer.
- A magnetic ballast or fluorescent ballast is sometimes more cost-effective than a general-purpose lighting ballast or electronic ballast. Magnetic ballasts and fluorescent ballasts are used mainly in gas discharge lamps to provide a high enough voltage to start the discharge. The magnetic ballast or fluorescent ballast then decreases the electrical current to the lamp in order to maintain the appropriate discharge.
- High intensity discharge ballasts (HID ballast) can be used in a high pressure sodium lamp, low pressure sodium lamp, or mercury lamp.
- Metal halide ballasts are designed for use in a metal halide lamp.
Each type of lighting product requires a mechanism, the ballast, to create and sustain the arc of electricity between the two electrodes within the arc tube.
Ballasts are used in a variety of industries and applications. For example, electronic ballasts are used in vision examination rooms and areas such as restrooms that use a motion detector switch. HID ballasts are an important part of many industrial lighting systems. Many different types of ballasts are used in fluorescent lighting in schools, businesses, and shopping malls.
Standards for ballasts can be found at the IHS standards store.