As can be seen, there are several ways to sense the end- of-life of a small diameter fluorescent lamp when the emissive electrode coating material is finally depleted by rising maximum electrode area dissipation and lamp sur- face temperatures to set trip levels. In the case of the T2 lamps, sensing the DC voltage across the lamp resulting from lamp voltage wavefrom asymmetry offers several clear advantages over the other methods reviewed in this paper. The DC sense voltage is independent of lamp volt- age variation. The DC sense voltage is independent of lamp length. And the DC sense voltage is independent of the number of series connected lamps in multiple lamp ballasts.
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