Abstract: A method for operating a fluorescent lamp (5) having a nominal power (WLa) and stabilized with an EM ballast (B) comprises the steps of during normal operation, short-circuiting the lamp during a closing time interval (CTI) during each current period in order to operate the lamp at a reduced power. The method comprises the step of detecting whether the lamp is stabilized by means of an inductive ballast or by means of a capacitive ballast. If it is found that the ballast is capacitive, the timing of the closing time interval (CTI) is set such that the closing time interval (CTI) has a first closing time segment (CTS1) immediately before a zero-crossing of the current, having a first duration (?1) higher than zero, and a second closing time segment (CTS2) immediately after said zero-crossing of the current, having a second duration (?2) higher than zero.

Abstract: A method for operating a fluorescent lamp (5) having a nominal power (WLa) and stabilized with an EM ballast (B) comprises the steps of during normal operation, short-circuiting the lamp during a closing time interval (CTI) during each current period in order to operate the lamp at a reduced power. The method comprises the step of detecting whether the lamp is stabilized by means of an inductive ballast or by means of a capacitive ballast. If it is found that the ballast is capacitive, the timing of the closing time interval (CTI) is set such that the closing time interval (CTI) has a first closing time segment (CTS1) immediately before a zero-crossing of the current, having a first duration (?1) higher than zero, and a second closing time segment (CTS2) immediately after said zero-crossing of the current, having a second duration (?2) higher than zero.

Abstract: The invention relates to a low-pressure mercury vapor discharge lamp (10) comprising a metal compound which is selected from the group formed by compounds of titanium, zirconium, hafnium and their mixtures. The effect of adding the metal compound selected from said group to the gas filling of the discharge space (14) results in an increased efficiency of the low-pressure gas discharge lamp (10), because part of the emitted light from the discharge space (14) is in the visible range of the electromagnetic spectrum. In one embodiment of the invention, the low-pressure gas discharge lamp (10) produces substantially white light without the use of a luminescent layer (16) comprising a luminescent material. In another embodiment of the invention, the luminescent layer (16) is applied to the discharge vessel (12) of the low-pressure gas discharge lamp (10). The light emitted by the luminescent material can be mixed with the light emitted from the discharge space (14) to produce the required color.