Electrical Illumination and Design

Transcription

1 EE512 Electrical Illumination and Design Prepared by: Engr. John Michael Abrera Table of Contents 1. Introduction 2. Luminaires, Lighting fixtures and Light fiitings 1

2 LIGHTING SYSTEM A lighting system is defined as one or more luminaire with one or more lamps having a characteristic lighting distribution. Illumination required for different purposes Standards 2

3 Design of lighting schemes and layouts A well designed lighting scheme is one which: 1. provides adequate illumination 2. avoids glare and hard shadows 3. provides sufficiently uniform distribution of light all over the working plane Depreciation, Maintenance Factor (ρ) or light loss factor (L LF ) This factor allows for the fact that effective candle power of all lamps or luminous sources deteriorates owing to blackening and /or accumulation of dust or dirt on globes and reflectors etc. Similarly, walls and ceilings also do not reflect as much as light as when they are clean. The value of this factor may be taken as 1/1.4 if the lamp fittings are likely to clean regularly or 1/1.5 if the is much dust. ρ = Illumination under actual conditions Illumination when everything is perfectly clean 3

4 Total Lumens Since illuminations is specified in lm/m2, the area in square meter multiplied by the illumination required gives the total useful flux that must reach the work plane. Taking into considerations the utilization and depreciation factors, the expression for gross lumens is: Illumination under actual conditions ρ Φ = E x A Illumination when η everything x ρ is perfectly clean Number of lamps and lamp arrangement The actual spacing and arrangement is governed by space / height values and the layout of ceiling beams or columns. Space / Height Ratio The actual spacing and arrangement is governed by space / height values and the layout of ceiling beams or columns. Space ρ SHR = = Height 4

5 s Example 1 Find the spacing between luminaires for a given shr of 1.5:1 if the mounting height is 2m Ans. 3m Example 2 The illumination in a drawing office 30m x 10m is to have a value of 250 lux and is to provided by a number of 300W filament lamps. If the cu is 0.4 and η is 0.9, determine the number of lamps required. The luminous efficiency of each lamps is 14 lm/w. Ans. 50 s Example 3 Design a suitable lighting scheme for a factory 120m x 40m with a height of 7m. Illumination required is 60 lux. Determine the number of lamps and state the arrangement of the lamps to cover the area. The lamps are 40W fluorescent lamps giving 45 lm/w. Depreciation factor is 1.2 and utilization factor is 0.5. Ans. 384 lamps, 192 fittings, 8 rows & 24 columns Example 4 A drawing hall in an engineering college is to be provided with a lighting installation. The hall is 30m x 20m x 8m. The mounting height is 5m. The required level of illumination is 144 lux. Using metal filament lamps, estimate the size and numbers of single lamps luminaires and also draw their spacing layout. (assume cu = 0.6; mf 0.75; space/height ratio = 1; efficacy: 300W lamps = 13 lm/w; 500W lamps = 16 lm/w) Ans. 24 lamps, 4 x 6 5

6 s Example 5 A production area in a factory measures 60m x 24m. Find the number of lamps required if each lamp has a lighting design lumen (LDL) output of 18,000 lumens. The illumination required for the factory area is 200 lux. Utilization factor is 0.4 and lamp maintenance factor is show also the lighting design layout if the shr is 3:2. the mounting height is 4m. Ans. 54, 4x14 or 5x11 s Example --- A function hall 40m x 25m x 6m is to be illuminated with metal filament gas filled lamps to an average illumination of 90 lux on a working plane 1 meter above the floor. Estimate the suitable number, size and mounting height of the the lamps. Sketch the spacing layout. Other details: cu = 0.5; df = 1.2 and shr = 1.2 Lamps: 200W 300W 500W Efficacy: Ans. 24 (500W), 4 x 6, 5m 6

7 s Instructions 1 Determine the room dimension in meters 2 Determine the nature of activity or task for the given area 3 Determine the required illumination level (lux) for the task or activity 4 Select the type of lamp to be used 5 Calculate the room cavity ratio (RCR) RCR = 5 x height (length + width) length x width 6 Determine the coefficient of utilization (based on item 4 above). Choose from table 1 7 Determine the maintenance factor. Choose from table 2 8 Determine the number of lamps / luminaires s Instructions 9 Calculate the total power consumption of the installed luminaires (lamp plus ballast) 10 Arrange the luminaire in a suitable grid or install the luminaires symmetrically 11 Repeat steps 5-9 using other lamps for the comparison of the cost of operation 12 Compare the total power consumption of the selected lamps 13 Select the lamp with lowest energy operating cost Note: Selection of lamps should not compromise the minimum required lux level for a given task for that area or space From: EEL design and Savings calculator Philippine Efficient Lighting Market Transformation Project 7