HPSV lamps

Yes, there is a relationship.

Let's take a 400 watt High Pressure Sodium (HPS) Lamp as an example. The Philips Ceramalux 400W HPS Lamp, Part#C400S51/ALTO, has an initial Lumen of 50,000. The rated life is 24,000+ hours.

At 40% of lamp rated average life the lumens will be approximately 45,000 lumens or 10% less. When the lamp is at 90% of rated average life, the lumens drop off significantly. We call this period "end of life" for the lamp.

Note regarding rated average life: Rated average life is the life obtained, on the average, from large representative groups of lamps in laboratory tests under controlled conditions at 10 or more operation hours per start. It is based on survival of at least 50% of the lamps and allows for individual lamps or groups of lamps to vary considerably from the average. For Lamps with a rated average life of 24,000 hours, life is based on survival of 67% of the lamps.

MrHandyMan