Conventional Ballast ( KVG)
So-called conventional ballasts ( KVG) consist of a choke, usually an iron core wound with copper wire. Due to the ohmic resistance of the copper (the so-called copper losses) and the magnetic core and eddy current losses in the core, heat generation and power losses of about 10-20% of the lamp power occur, see our consumption diagram.
The KVG is connected in series with the lamp and must match the lamp, as it limits the current of the lamp to its nominal value at the mains frequency of 50 or 60 Hz.
KVG for fluorescent lamps also require a so-called starter, which switches the hot cathodes at startup for preheating directly into the circuit. Glow starters cause the characteristic flickering of fluorescent lamps at start, fast starters do not have this disadvantage.
Due to their inductance, conventional ballasts cause reactive current in the grid. In some cases, luminaires are therefore equipped with a reactive current compensating capacitor (reactive current compensation).
When converting to LED tubes, the conventional starter is replaced by an LED starter.
The KVG is thus bridged and produces virtually no more power loss.
The successor to the conventional ballasts was the low-loss ballast ( VVG).