Patent ID: 6717371
Filing Date: 2004-04-06
Classification: H05B

Abstract:
A ballast for operating a plurality of low-pressure discharge lamps, the ballast having three parallel-connected branch circuits to which electric terminals for at least one low-pressure discharge lamp are connected, whereinthe ballast has a first transformer for balancing the lamp currents, the first transformer has a first and a second winding, the first winding having twice as many turns as the second winding, the ballast has a second transformer for balancing the lamp currents, the second transformer having a first and a second winding, and the first winding having twice as many turns as the second winding, the windings of the transformers are arranged in such a way that when the low-pressure discharge lamps are connected the lamp currents flow firstly through the windings of one of the two transformers, then through the low-pressure discharge lamps and only then through the windings of the other transformer, the first winding of the first transformer is arranged in such a way that when the low-pressure discharge lamps are connected it is flowed through by the lamp current of the low-pressure discharge lamp or low-pressure discharge lamps connected to the first branch circuit, the second winding of the first transformer is arranged in such a way that, with the low-pressure discharge lamps connected, it is flowed through by the lamp currents of the low-pressure discharge lamps connected to the second and third branch circuit, the two windings of the first transformer (Tr10) being wound in opposite senses, the first winding of the second transformer is arranged in such a way that, with the low-pressure discharge lamps connected, it is flowed through by the lamp current of the low-pressure discharge lamp or low-pressure discharge lamps connected to the third branch circuit, and the second winding of the second transformer (Tr11) is arranged in such a way that, with the low-pressure discharge lamps connected, it is flowed through by the lamp currents of the low-pressure discharge lamps connected to the first and second branch circuit, the two windings of the second transformer being wound in opposite senses.