International Journal of Engineering Trends and Technology (IJETT) - Volume4Issue5- May 2013
LED Lamp Detailed Design
Parameters
K. Ajay Sai Mohan#1,
#
ECE Department, K L University,
M. Anil Kumar*2,
Asst.Professor, ECE Department, K L University,
Vaddeswaram, Andhra Pradesh, India.
Abstract:-Light by definition is the form of
electromagnetic form of energy that has a wavelength
from 400nm to 700nm of visible light. All human
activities are done round the clock. Before we go any
further, it is worth looking at definition for lighting.
“We say the lighting is good, when our eyes can
clearly and pleasantly perceive the things around us”.
So Artificial light should be Functional and pleasant
both Physiologically and Psychologically. This is often
achieved employing multiple sources. Also the form of
energy should be efficient and usable by everyone. As
all of us are aware, all sources today employ electrical
energy.
Keywords:- Lumen, Wattage, Pitch, Diffuser Sheet,
Troffer.
I. INTRODUCTION
Light is the Radiant Energy that provides
visual sensation. It is similar to radiant heat.
But has different frequencies and
wavelengths. However, Visible Light –
spans from 180nm to 700nm wavelength.
It must be mentioned that human Eye
responds from 380 (violet) to 700nm (red).
This becomes necessary for us to
understand the suitability of various types
of sources of light.
II. DESIGN PROCEDURE
A. PCB of LED’s is designed based on
various parameters:
1. Estimation of LUMEN.
2. No of LED’s required.
3. Selection of resistor.
4. Selection of reflector material.
5. Pitch and height.
B. Estimation of LUMEN:
Whenever we need to design a
lamp first we should know how much
lumen that the lamp should produce. The
ISSN: 2231-5381
amount of lumen depends upon the room
in which the lamp should be installed, at
what height the lamp should be placed and
the area the lamp should cover.
C. No of LED’s required:
6. Total number of LEDs = Total
Lumens required / LED Lumen
7. Total number of Bunches Total LEDs
/ LEDs per Bunch
8. Total current=Each LED current *
Total Bunches
9. Total Voltage = LED cut in voltage *
No: of LEDs per Bunch
10. Total Wattage = Total current * Total
voltage
11. Efficacy obtained with out diffuser =
Lumens obtained / Wattage
Each Lamp contains a Diffuser sheet,
there obtained a loss of 35% Lumen.
Lumen obtained after the addition of
diffuser sheet = 65% (Lumen without
diffuser) Losses due to diffuser sheet has
to be compensated by addition of LEDs to
maintain the required Lumen.
1. No. of LEDs to be added = Drop in
the Lumen / Each LED Lumen
2. Total bunches with diffuser= Total
LEDs with diffuser/ LEDs per Bunch
3. Total current with diffuser= Each
LED current * Total number of
Bunches with diffuser
4. Total Wattage with diffuser= Total
current with diffuser * Total voltage
5. Total Efficacy with diffuser = Lumens
obtained with diffuser / Total Wattage
with diffuser
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International Journal of Engineering Trends and Technology (IJETT) - Volume4Issue5- May 2013
Based on Lumens required, the troffer
parameters are designed.
7.5W 1 X 1 Troffer(osrum)
Lumens
706
Required
Cut in Voltage
2.94
LED
20
current(mA)
LED lumen
8.55
Wattage
7.47
Obtained
Lumens
with
706.00
diffuser
Total
LED's
127.04
with diffuser
Total Bunches
18.15
with diffuser
Measurment Of troffer
Lenght (Feet)
1
Width (Feet)
1
Length
30.32
(Centimetre)
Width
30.32
(Centimeter)
Cut in Area
Length
28.32
(Centimeter)
Width
28.32
(Centimeter)
No of columns
11
No of rows
11
Column pitch
2.51
Row pitch
2.51
Total Efficacy
with
diffuser 94.52
(lm/W)
Efficacy
obtained with 145.41
out diffuser
PCB type
Single side
No: of LEDs
121
Osrum cost
302.5
Nichia cost
544.5
ISSN: 2231-5381
III. SELECTION OF RESISTOR
Never connect an LED directly to
a battery or power supply. It will be
destroyed almost instantly because too
much current will pass through and burn it
out. LEDs must have a resistor in series to
limit the current to a safe value. Resistor
value is selected based on the cut-in
voltage and forward current of the LED
used.
IV.SELECTION OF REFLECTOR MATERIAL
Reflecting surfaces are used mainly to get
uniform illumination. There are two types
of reflector sheets that are used in troffer
lighting. One is glass and the other is
poly-carbonate sheet. Now a days diffuser
sheet is used .Killing of lux is observed
nearly up to 35%(loss). To compensate the
losses LEDs are added.
V.PITCH AND HEIGHT
PITCH : The distance between two
adjacent LED’s in PCB .
HEIGHT : Height at which the reflector
sheet is placed. It is decided based on
the requirement of LUX and illumination.
By using these concepts we design troffer
lights of required wattage and lumen.
VI. BASED ON WATTAGE
A. Estimation of Wattage:
Whenever we need to design a
lamp first we should know how much
wattage that the lamp should produce. The
amount of wattage depends upon the room
in which the lamp should be installed, at
what height the lamp should be placed and
the power the lamp should cover.
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International Journal of Engineering Trends and Technology (IJETT) - Volume4Issue5- May 2013
10W 1 X 1 Troffer(nichia)
Lumens Required
706
Cut in Voltage
2.95
LED current(mA)
40
LED lumen
13.50
Wattage
9.49
Obtained
Lumens with
706.00
diffuser
Total LED's with
80.46
diffuser
Total Bunches
11.49
with diffuser
Measurement Of troffer
Length (Feet)
Width (Feet)
Length
(Centimeter)
Width
(Centimeter)
Cut in Area
Length
(Centimeter)
Width
(Centimeter)
No of columns
No of rows
Column pitch
Row pitch
Total Efficacy
with diffuser
(lm/W)
Efficacy
obtained with
out diffuser
PCB type
No: of LEDs
Osram cost
Nichia cost
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1
1
30.32
30.32
B. No of LED’s required:
1. Total voltage=LED cut-in voltage *
Total No:of LEDs per bunch
2. Total current=Total Wattage / Total
voltage
3. No: of bunches=Total current / LED
current
4. Total No: of LEDs=No: of bunches *
No: of LEDs per bunch
5. Total lumen=Total No: of LEDs *
Each LED lumen
6. Efficacy of lamp=Total lumen / Total
wattage
VII.CONCLUSION
This design helps to design a lamp
effectively with more efficiency based on
lumens and wattages, thus give the best
results in the longevity of the lamp.
REFERNCES
28.32
28.32
9
9
3.16
3.16
1. http://en.wikipedia.org/wiki/Printed_cir
cuit_board
2. S Muthu, J Gaines - … IAS Annual
Meeting. Conference Record of …, 2003 ieeexplore.ieee.org
4. G Zorpette - Spectrum, IEEE, 2002 ieeexplore.ieee.org
74.36
114.41
Single side
80
201.14
362.05
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