PPT On Illumination Engineering

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Illumination Engineering Presentation Transcript:
1.Power Distribution & Utilization

2.Contents To Be Covered:
Introduction
Terms Used in Illumination
Laws of Illumination
Photometry
Measurement of Illumination
Sources of Light
Arc Lamps
Incandescent Lamps
Basic Principles of Light Control
Types of Lighting Scheme
Design of Lighting Scheme
Factory Lighting
Street Lighting
Flood Lighting

3.Introduction:
Light is the prime factor in human life.
All activities ultimately depend upon the light.
Artificial light is used in absence of natural light.
Artificial light due to its cleanliness, ease of control, reliability, steady output, low cost is playing a great role in our lives.
Science of illumination engineering is, therefore,  becoming of major importance.

4.Nature of Light:
Light is a form of radiant energy.
Depends on the temperature of bodies emitting them.
Heat of the body can be classified as red hot or white hot.
When the temperature increases, the body changes from red hot to white hot.
Higher the temperature of the body, lower the wavelength of radiant energy, and higher the radiant efficiency.

5.Color:
The sensation of color is due to the difference in wavelengths of the light radiations.
Visible light can have a wavelength between 4,000Aº  and 7,500Aº.

6.Relative Sensitivity:
Sensitivity of the eye to the lights of different wavelengths varies from person to person and according to the age.
Eye has greatest sensitivity for wavelengths of about 5,500Aº
The relative sensitivity at any particular wavelength ? is written as k? and known as relative luminosity factor.

7.Illumination:
It differs from light very much.

Light is the cause and illumination is the result of that light on surfaces on which it falls.

8.Terms Used in Illumination
Light: defined as radiant energy.
Luminous Flux: defined as total quantity of light energy emitted per second from a luminous body.
Luminous Intensity: it is the luminous flux emitted by the source per unit angle.
Lumen: it is the unit of luminous flux.
Candle Power: it is the light radiating capacity of the source in a given direction. Denoted by CP.
Illumination: when light falls upon any surface, it is called illumination.
Lux or Metre Candle: it is the unit of illumination.
Candela: it is the unit of luminous intensity.

9.Mean Horizontal Candle Power (MHCP): it is the mean of candle powers in all directions in horizontal plane containing source of light.
Mean Spherical Candle Power (MSCP): it is the mean of candle powers in all directions and in all planes from source of light.
11. Mean Hemi-Spherical Candle Power (MHSCP): it is the mean of candle powers in all directions above or below the horizontal plane.
12. Reduction Factor:
                   MSCP/MHCP
13. Lamp Efficiency: ratio of luminous flux to the power input.

10.Laws of Illumination:
Law of Inverse Squares: if a source of light which emits light equally in all directions be placed at the centre of a hollow sphere, the light will fall uniformly on the inner surface of the sphere, that is to say, each square mm of the surface will receive the same amount of light.

11.Lambert’s Cosine Law:
   The illumination at any point on a surface is proportional to the cosine of the angle between the normal at that point and the direction of luminous flux.

12.Photometry:
The candle power of a source in any given direction is measured by comparison with a standard or substandard source employing photometer bench and some form of photometer.
Photometer bench essentially consists of two steel rods which carry the stands or saddles for holding the two sources.
The principle of most of the methods of measurement is based upon inverse square law.

13.Types of Photometers:
Most common type of photometers are:
Bunsen Grease Spot Photometer: consists of a piece of tissue paper with grease spot in the centre.
Flicker Photometer: used when two sources giving light of different colors are to be compared.

14.Measurement of Illumination
The best method of measuring illumination is by a portable type illumination photometer calibrated to read directly in lux.
No shadow should be allowed to fall on the meter during measurements.
Meter should be held perfectly horizontal and stationary for accurate results.
Meter should be color corrected type so that it can be used for all kinds of light sources.

15.Sources of Light:
Light sources may be grouped as:
Arc Lamps
High Temperature Lamps
Gaseous Discharge Lamps
Fluorescent Type Lamps