The latest LED technology opens up wide areas for new applications, new technical possibilities and reduced costs. The main advantages of the state of the art LED light sources are:
The table below lists the properties of different light sources including costs of ownership:
Type |
Wattage |
Luminous flux init, avg |
Efficiency |
Color Rendering index Ratio |
CCT (color temperature) |
Life time |
Costs for 1 lm/h |
[W] |
[lm] |
[lm/W] |
[%] |
[K] |
[h] |
[?] |
|
Incandescent |
60 |
865 |
14.4 |
100 |
2790 |
1000 |
69 |
Tungsten Halogen |
50 |
590 |
11.8 |
100 |
2700-4000 |
2000 |
85 |
Fluorescent Triphosphor |
32 |
2850 |
84 |
78 |
4100 |
24000 |
12 |
Compact Fluorescent |
15 |
900 |
51 |
82 |
6000-2700 |
10000 |
20 |
Low Pressure Sodium |
90 |
12750 |
123 |
44 |
n.a. |
16000 |
8 |
High Pressure Mercury |
250 |
11200 |
34 |
50 |
3900 |
24000 |
29 |
Metal Halide |
400 |
36000 |
60 |
65 |
4000 |
20000 |
17 |
Induction Coupled Fluorescent |
55 |
3500 |
64 |
80 |
3000 |
100000 |
15 |
LED White (high end) |
1 |
70 |
70 |
85 |
6000 |
50000 |
14 |
LED White (standard) |
1 |
40 |
40 |
85 |
6000 |
50000 |
25 |
LED Warm White |
1 |
20 |
20 |
75 |
2900 |
50000 |
50 |
LED Amber |
1 |
50 |
50 |
n.a. |
n.a. |
100000 |
20 |
LED Red |
1 |
40 |
40 |
n.a. |
n.a. |
100000 |
25 |
The calculation is based on a price of 0,1 € / kWh. This LED- data has been taken from different data sheets of top suppliers. Due to the diverse applications the costs of maintenance and ownership need to be calculated against the relevant application. The loss of power supplies has not been considered. One key aspect in the application of LEDs as light sources is the management of thermal loss. This problem is new for LED applications, previous typical slogans are “LEDs are low cost, low heat, and have low failure rates”. The LED producers resolved the problem of the thermal resistance between the LED chip and the connecting pad with different solutions like metal core PCB, specially designed lead frames, to based solutions and ceramic-based packages.
Good solution can provide a thermal resistance between p/n junction and solder pads below 20 K/W. The excess heat can be removed by different passive and active ways. The metal core P.C.B. or flexible P.C.B. usually directly mounted on a heat sink or air fan or in specials cases water cooling is used to keep the p/n junction temperature below the critical limit. In addition one should consider that the radiant intensity has a negative temperature coefficient. As an example red LEDs have an TC in the range of -0,5 % / °C and an increase of the p/n junction temperature from room temperature (20°C) up to 85 °C reduces the radiant intensity by 32.5%.
The picture shows a solution for the thermal management of a warm white LED source for a street lamp. The warm white LED modules for this street lamp were developed by OSA Opto Light GmbH, Germany.
Considering all the aspects shown above, the direct replacement of conventional lamps is an interesting way to increase the reliability of systems and to reduce the real costs of ownership. The state of the art LEDs show clear advantages for all applications, where colored light sources are necessary. In near future we will see white LED light sources with further cost benefits and increased external efficiency, which will again show clear advantages over conventional light sources.
Any question, please feel free to contact:
BBE TEAM
Tel.: +86 755 2958 8988 Ext. 837 Fax: +86 755 2958 8616
Mobile: +86 185 7520 6951
E-mail: bbe@bbeled.com
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