| 摘要 |
"Switching arrangement" The invention relates to a switching arrangement for operating a high-pressure sodium lamp (1) which radiates white light in stable operating conditions. The switching arrangement is provided with switching means (5) for switching current through the lamp by means of a drive signal generated in a drive circuit (6), which signal is based on a comparison between a reference value C and a drive signal V+.beta.I, in which V is the lamp voltage, I is the lamp current, and .beta. is a constant. According to the invention, C may be adjusted in steps in dependence on the lamp voltage. Thus the duration over which the lamp radiates white light can be prolonged and brought into better accordance with the electrical lamp life. Fig. 1.
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