These electrical devices vary greatly in complexity, from as simple as a series resistor used with small neon lamps to very complex ones that are computerized and used with fluorescent lamps. Ballast manufacturers have to adhere to different manufacturing standards that approve the quality of products on various parameters.
Ballasts are commonly required when an electrical device or circuit poses a negative resistance to the supply. If such a device is connected to a constant-voltage power supply, it would draw a large amount of current until a time it was destroyed or caused the power supply failure. A ballast is used for preventing this situation and provides a positive resistance that limits the ultimate flow of current to an appropriate level.
Ballasts can also be used simply to deliberately reduce the current flow in an ordinary, positive-resistance circuit. Prior to the advent of solid-state ignition, automobile ignition systems commonly included a ballast resistor to regulate the voltage applied to the ignition system.
Types of Ballasts
There are various ballasts available in the market depending on their end applications. They can be categorized as:
- Electronic ballasts: These ballast use semiconductors
for increasing the frequency of fluorescent lamp operation, which is
normally in the range of 20 - 40 kHz .
- Magnetic ballasts: These ballast are mainly used in gas
discharge lamps for providing a high voltage required for starting
the discharge. The ballasts are sometimes more cost effective than
electrical ballasts.
- High intensity discharge or HID ballasts: These ballast are used in high pressure sodium lamps, low pressure sodium lamps, or mercury lamps. Ï Metal halide ballasts: These ballast are manufactured for use in metal halide lamps.
Different types of ballasts find application in a variety of industries.
- Schools
- Business Centres
- Shopping malls
- Industrial lighting system
