liitäntälaitteesta

Liitäntälaite, known in English as a ballast, is an electrical component used to limit current in an electrical circuit. In its most common application, it is used with fluorescent and high-intensity discharge (HID) lamps. These types of lamps require a much higher voltage to start than they need to operate. The ballast provides this initial voltage surge and then regulates the flow of electricity to the lamp during operation, preventing it from drawing too much current and burning out.

There are two main types of ballasts: magnetic and electronic. Magnetic ballasts, the older technology, use a transformer to regulate current. They are generally heavier, less energy-efficient, and can produce a noticeable hum. Electronic ballasts, on the other hand, use solid-state components to convert the mains frequency to a much higher frequency. This higher frequency makes the lamps operate more efficiently, produce less heat, and eliminates the humming sound. Electronic ballasts are lighter and consume less power.

Without a ballast, a fluorescent or HID lamp would essentially become a short circuit once it ignites, leading to rapid failure and potentially damaging the power source. The ballast ensures stable operation and extends the lifespan of the lamp. While primarily associated with lighting, the principle of current limiting using a ballast is also applied in other electrical circuits where precise control of current is necessary.