 Induction lamp |
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| Products Description |
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| LVD Theory & Parameters |
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| Table 1. Conversion factors for lumens to pupil lumens |
| Correction factors applied to conventional values of lumens per watt yield a value for pupil lumens per watt, which is a measure of how effectively the eye sees the light that is emitted. The pupil is more receptive to light at the blue end of the spectrum. |
| Light source |
Conventional lumensper watt |
Correction factor(P/S ratio) |
Pupil lumens perwatt |
| Low-pressure sodium |
165 |
0.38 |
63 |
| 5,000-K T5 fluorescent |
104 |
1.83 |
190 |
| 4,100-K T8 fluorescent |
90 |
1.62 |
145 |
| Clear metal halide |
85 |
1.49 |
126 |
| 5000-K LVD Lamp |
80 |
1.62 |
129 |
| 5,000-K pure triphosphor fluorescent |
70 |
1.58 |
111 |
| 3,500-K triphosphor fluorescent |
69 |
1.24 |
85 |
| 50-watt high-pressure sodium |
65 |
0.76 |
49 |
| 2,900-K warm white fluorescent |
65 |
0.98 |
64 |
| Daylight fluorescent |
55 |
1.72 |
95 |
| 35-watt high-pressure sodium |
55 |
0.57 |
31 |
| 5,000-I 90 CRI fluorescent |
46 |
1.7 |
78 |
| Vitalite fluorescent |
46 |
1.71 |
79 |
| Deluxe mercury vapor |
40 |
0.86 |
34 |
| Standard incandescent |
15 |
1.26 |
19 |
| Tungsten halogen |
22 |
1.32 |
29 |
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| Summary |
Recent studies seem to favor white light (as from induction lamps) for viewing moving objects in low-light conditions, such as spotting a pedestrian, animal, or other moving object off to the side of the roadway at night. Some cities opt to use white light rather than the yellowish light of high-pressure sodium (even though the price is higher) in hopes of reducing accidents. The improved color rendering of white light in retail areas and places where people congregate after dark make it a popular choice for street lighting in downtown areas.
Induction lamps produce high quality white light. More lamps and fixtures are becoming available, but they do carry a premium price and still have limited applications. The long life of these lamps can substantially reduce maintenance costs due to relamping.
White light is proving to have advantages for visual performance. Current codes and standards are based on measurements that do not address the impact of pupil lumens, and pupil lumens can be quite different from traditionally measured lumen output of lamps. Studies on the relevance of light spectrum and the mechanics of vision are ongoing, and codes and standards may reflect that in the future. |
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