ABSTRACT
Lamp voltage of all electrodes showed rise up with the lapse of burning hours. Especially electrode C showed steep increase. This is because emitter was exposed directly to the discharge space. 150 Emitter sputtered heavily and caused severe blackening near the both ends of the arc tube. It brought higher temperature of the coldest 100 spot of the arc tube. This means increase of lamp voltage and lower lumen maintenance. Electrode E showed the smallest increase 50 in these five electrodes. Figure 4 shows the lumen maintenance of 9
-4 0 electrode E. The reason why good lumen maintenance was kept is that these lamp were operated on inductive type ballasts and lamp wattage went up with the increase of lamp voltage until around 118V.
