| 摘要 |
A method, apparatus, and system for compensating for lamp lumen depreciation. The method includes operating the lamp under rated wattage for a period towards the first part of operating life of the lamp. Operating wattage is increased at one or more later times. Energy savings are realized. The increases also restore at least some light lost by lamp lumen depreciation. The apparatus uses a timer to track operating time of the lamp. A few wattage changes made at spaced apart times can be made in a number of ways, including changing capacitance to the lamp, or using different taps on the lamp ballast. In one aspect the invention pertains to solid state sources. The invention can pertain to a variety of applications including wide area lighting, indoor lighting, pathway lighting, parking lot lighting, street lighting, under-counter or -cabinet lighting, and others.
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