Illumination Example 4
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The document provides assumptions and considerations for designing illumination problems. It assumes factors like depreciation, maintenance, utilization, and glare and shadow avoidance. It then works through an example of designing lighting for a 40m by 15m hall requiring 75 lux illumination. It calculates the gross lumens and wattage required, selects fluorescent tubes, and determines 40 lamps in 4 rows of 10 lamps each would be suitable. Finally, it provides the layout and spacing calculations.
Illumination Example 4
- 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 = 0.6 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 -4 • An illumination of 75 Lux is required on working plane in a big hall of (40 m (L) X 15 m (b)). The lamps to be hung 4 m above the work bench. Assuming a suitable space height ratio, a utilization factor of 0.5, a lamp efficiency of 14 lumens per Watt and candle power depreciation of 20 %, Estimate the no. rating and disposition of lamps.
- 4. Design considerations • Illumination required is = 75 lux. • Candle power depreciation + Depreciation Factor = 1 • Depreciation Factor = 1 - Candle power depreciation = 1- 0.2 = 0.8
- 5. Calculation of No. of lamps required • From Table on Lamp Data, for the Fluorescent lamp selecting wattage of 36 (82/84/86) with Lumen output = 3250 A×E Gross Lumenn required = M.F × U.F. (40 15) 75 = 0.5 0.8 = 112500 Gross Lumen Total Wattage required= Lumen Efficiency 112500 = 14 = 8036 Watts 8036 So, No. of lamps of 200 W each = 40 200 40 lamps in 4 rows each having 10 lamps can be used.
- 6. Layout • 200W Lamp selected. • Taking arrangement as • No. lamps in one row = 10 • No. of rows = 4 • 2 lamps for black board • Distance along the length, a = 40/10 = 4m • Distance along the width, b = 15/ 10 = 1.5m • Side Length = a / 2 = 4 / 2 = 2m • Side Width = b/2 = 1.5 / 2 = 0.75m • NOTE:- Draw a layout
- 7. S Ratio = Spacing Between Lamps H Height of mounting of Lamp Along Length 4 1 4 S Ratio 1 H Along Width 1 .5 0.375 4 S Ratio 0.375 H Vijay Balu Raskar (B.E.Electtrical)
- 8. HOME WORK-4 • An illumination of 95 Lux is required on working plane in a big hall of (26 m (L) X 30 m (b)). The lamps to be hung 5 m above the work bench. Assuming a suitable space height ratio, a utilization factor of 0.5, a lamp efficiency of 14 lumens per Watt and candle power depreciation of 18 %, Estimate the no. rating and disposition of lamps.
- 9. E-mail if any queries:- student5147@yahoo.com Or Contact:- 09833066325 Vijay Balu Raskar (B.E.Electtrical)