Introduction & Basic Definitions

CONTENTS:

1. INTRODUCTION

2. BASIC DEFINITIONS

3. LIGHTING SOURCES & SCHEMES

4. LIGHTING LUMINARIES IN OIL & GAS FIELD & LIGHTING INSTALLATION DETAILS

5. LIGHTING SYSTEM DESIGN

6. LIGHTING CIRCUITS DISTRIBUTION CRITERIA

7. PANEL SCHEDULE

1. INTRODUCTION:

The purpose of the lighting is to serve the needs of persons.

Quality of illumination implies that all luminance are designed to contribute favorably to visual performance, visual comfort, ease of seeing and safety for specific visual task involved.

Glare, diffusion, direction, shadows, uniformity, color, luminance and luminance ratios have significant effects of visibility & should be considered during lighting design.

2. BASIC DEFINITIONS

2.1. WHAT IS LIGHT?

Light is the medium through which we can recognize the world surrounding us In physical words: Light is a kind of electromagnetic radiation that consists of ripples or waves that are

propagated in an omnipresent electric and magnetic field, and travelling away from its source uniformly in all directions, unless intercepted.

2.2. NATURE OF LIGHT

Various forms of incandescent bodies are the source of light, and the light emitted by such bodies depend upon its temperature.

As the temperature increases the wavelength of the radiated energy becomes smaller and smaller and enters into the range of the wavelength of light.

The wavelength which can produce the sensation of light varies from 380 nm to 780 nm

White light emitted by the sun consists of a mixture of various wavelengths in the visible spectrum:

2.3. THE FOUR BASIC LIGHTING QUANTITIES

2.3.1. luminous flux :

The amount of light radiated per second by a light source

Unit: lumen (lm)          symbol : (Φ)

2.3.2. luminous Intensity :

The amount of light radiated by a light source in a given direction

Unit: candela (cd) or (lumen/steradian)                symbol : (I)

2.3.3. Illuminance:

The amount of light falling on a unit of surface

Unit: lux (lux=lm/m2)          symbol : (E)

Illuminance is independent of the direction from which the luminous flux reaches the surface

2.3.4. luminance:

The amount of light radiated by a unit of apparent surface in a given direction

Unit: candela per m2 (cd/m2)            symbol : (L)

2.4. LAMP EFFICACY OR LUMINOUS EFFECACY:

Luminous efficacy (lm/W) =   

                                            Luminous flux / Electric power dissipated

2.5. LIGHT LAWS:

2.5.1. INVERSE SQUARE LAW :

Illumination is inversely proportional to the square of the distance between the source & the surface

2.5.2. COSINE LAW OF INCIDENCE :

Illumination is proportional to the cosine of the angle of incidence

E α Cos ( Ө )

So, form the previous two laws we will find that :

                E = Emax Cos ( Ө )

hence,

               E = (I / h2) Cos3 ( Ө )

                     

where :

E : Illumination at any point

I : luminous intensity of a given source

h : the vertical distance between source & surface

Ө : the angle of incidence

2.6. CO-EFFICIENT OF UTILIZATION (C.U.):

It is the ratio of the lumen actually received by the working plan to the total lumens emitted by the source

C.U. = Φ received by the working plan /  Φ emitted by the source

2.7. MAINTENANCE FACTOR (M.F.):

The effective candle power of all lamps due to accumulation of dust or dirt on the lamps globes, reflectors, walls & ceiling is taken into account by including the maintenance factor.

M.F. = L.L.D ( Lumen Lamp Deprecation ) x L.D.D ( Lumen Dirt Deprecation )

MF ~ 0.8 for indoor lighting

MF ~ 0.6 0.7 for outdoor lighting

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Ahmad Mohammad

Hi. I’m Designer of Mawsoo3a Blog. I’m Electrical Engineer And Blogger Specializing In Electrical Engineering Topics. I’m Creative.I’m Working Now As Maintenance Head Section In An Industrial Company.

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