Illumination Example 7
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The document discusses illumination based problems and examples. It notes assumptions that should be made when designing illumination projects, including depreciation, maintenance, and utilization factors. An example problem is provided to illustrate how to calculate average illumination produced on a classroom floor given the room size, number of lamps, wattage of each lamp, and mean spherical candle power of each lamp. The document provides design considerations and the calculation steps. It concludes by assigning another illumination calculation as homework.
Illumination Example 7
- 1. Illumination Based Problems Vijay Balu Raskar (B.E.Electtrical)
- 2. NOTE:- Before Designing assume following things clearly. Assumptions are required for illumination. Assume Depreciation Factor = 1.2 Assume Maintenance Factor = 0.8 Utilization Factor = 0.5 to 0.9 Assume illumination is free from glare Assume illumination is free from dark shadows Assuming lamps are arranged to give uniform illumination. Reflective index of wall and ceiling is maximum. Selecting a fluorescent tube light Space to height ratio along the length and breadth is less than or equal to 1.5 Assume Height of mounting of Lamp ( as per area) Vijay Balu Raskar (B.E.Electtrical)
- 3. Example -7 • A class room of size 15 X 6 m is to be illuminated by twenty 200W lamps. • The Mean Spherical Candle Power of each lamp is 250. Assume suitable data and find the average illumination produced on the floor. Vijay Balu Raskar (B.E.Electtrical)
- 4. Design considerations • Assuming an average illumination of E lux. • Assuming depreciation factor = 1.2 i.e.. Maintenance factor 0.8 • Utilization factor varies from 0.6 to 0.9 • Assume UF is 0.6 • Assuming illumination is free from glare • Assuming illumination is free from dark shadows. Vijay Balu Raskar (B.E.Electtrical)
- 5. Design considerations • Assuming lamps are arranged to give uniform illumination. • Reflective index of wall and ceiling is maximum. • Space to height ratio along the length and breadth is less than or equal to 1.5 • Selecting a fluorescent tube light • Selecting utilization factor of 0.6 Vijay Balu Raskar (B.E.Electtrical)
- 6. Calculation of Illumination • We have , • Total Lumen = No of Lamp X MSCP X 4π • Total Lumen = 20 X 250 X 4π • Total Lumen = 62831.853 Lumens • We have, • Lumens reaching on the working plane is, • =Total Lumens X UF = 62831.853 X 0.6 • DF 1.2 • = 31416 Lumens • And E = Lumen reaching / Area = 31416 / 90 = 350 Lux • Illumination is 350 Lux. Vijay Balu Raskar (B.E.Electtrical)
- 7. Home Work -7 • A class room of size 20 X 5 m is to be illuminated by twenty 300W lamps. • The Mean Spherical Candle Power of each lamp is 300. Assume suitable data and find the average illumination produced on the floor. Vijay Balu Raskar (B.E.Electtrical)
- 8. E-mail if any queries:- student5147@yahoo.com Or Contact:- 09833066325 Vijay Balu Raskar (B.E.Electtrical)