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These devices are basically switching power supplies that eliminate the copper and iron of conventional ballasts with an integrated high frequency inverter or switch.
Simply described, the ballasts contain three sections. A filter that protects the device from the irregularities in the mains supply and prevents RF and other interference to and from the ballast. A second stage that converts the 50Hz AC supply to DC and a third that consists of an inverter that supplies the lamp at high frequency with the correct voltage. This last section also includes a circuit that enables the preheating of the lamp where required and which is important for maximising lamp life.
Properly designed electronic ballasts are very reliable. In practice, reliability generally depends on their location in respect to the heat produced by the lamp, but other factors, such as wild over voltage fluctuations, spikes etc can also effect them. Since these ballasts include rectification, filtering, and operate the tubes at a high frequency, they usually eliminate the flicker associated with conventional ballasts.
Operating at anywhere between 20,000 and 40,000 Hz they consume up to 30% less power whilst producing the same amount of light. They are also quieter, lighter and have the potential for Dimming. There is no need for any additional components such as a starter or capacitor and this makes them quick and easy to install.
Most high frequency ballasts are used in conjunction with T8 (25mm diameter) and Compact lamps, but high frequency electronic ballasts are also required to power the new T5 linear & circular tubes and the new T2 lamps.
Amongst the other advantages are the ability to work on 50 or 60Hz and DC voltages, the ability to supply one or more lamps and lamps of different wattages, high power factor and the possibility of developing devices around manufacturers space and other design limitations.
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