Don't Kelvins refer to the frequency of the light waves and lumens are the intensity? I think you are comparing apples to oranges.
Most info I have seen on these arc bulbs is that they produce about 5 times as many lumens as a conventional resistance light bulb. One that runs at 6,000 kelvins is very close to dayllight that from my experience runs from 5500 to 7000 kelvins depending on the conditions. It should look very blue during the night and white during the day.