Wednesday, October 29, 2014
Tuesday, August 6, 2013
LED Lighting
LED
Understanding Theory
When electrical current runs through an LED, the electrons in the current flow into a semiconductor material containing electron "holes" (spaces) waiting to be filled with electrons. When the electrons fill those holes, energy is released as photons, or light that is emitted outward, turning the LED into a lightbulb. In contrast, incandescent bulbs generate light from the electrical resistance of a metal filament. The resistance method requires more electrical energy to heat up the filament to a point that it glows and emits light.
Like all lightbulbs, light-emitting diodes (LEDs) produce illumination by turning a given amount of electric current into light. LEDs perform this conversion more efficiently than standard incandescent bulbs.A typical Energy Star-rated LED uses 20 to 25 percent of the energy that an incandescent bulb uses.The LED lasts up to 25 times longer.
The amount of light a bulb generates can be measured in a unit called lumens. Electrical power is measured in a unit called watts. Due to their methodology of converting electricity into light, LED bulbs feature a higher ratio of lumens to watts than incandescent bulbs.
What's the difference
Traditional incandescent bulbs use a lot of energy to produce light. 90% of the energy is given off as heat
.That lost energy is money we are throwing away.Newer energy-saving lightbulbs provide the choices in colors and light levels you've come to expect. The new lights are also much more efficient ,so they save you money.
Understanding Theory
Lumens
A lumen is a measurement of light directly relevant to human beings. Instead of trying to measure the number of photons or raw radiated energy, the lumen scale describes the amount of light, or brightness, that the human eye perceives. All modern lightbulb packaging shows the number of lumens the bulb produces. An average 100-watt incandescent bulb, for example, produces about 1,600 lumens.
Watts
A watt is a measurement of electrical power, formally equal to the amount of energy in 1 ampere of current flowing at 1 volt. A lightbulb that is rated at, say, 200 watts uses more electricity to produce light than a bulb rated for 100 watts. The benefit, however, is that the 200-watt bulb produces significantly more light than the lower-rated bulb. The relative efficiency of different lightbulbs can be gauged by comparing how many lumens they produce for every watt of electrical power.
Watts and Lumens in LEDs
LEDs that are bright enough to replace incandescents for household use, producing the same number of lumens as standard 40- or 60-watt bulbs,typically only use 9 to 12 watts. The experts advises that consumers who want to replace a 60-watt bulb should look for an LED that produces close to 800 lumens; for a 40-watt bulb, look for 450 lumens . Now a days, manufacturers were just starting to produce high-powered LEDs for the home.
Light Quality
Lumens don't describe the quality of the generated light.Its color, tone or other variables. Some people find they don't like the light that certain LED bulbs produce, describing it as "cold," "pale" or "dim." The biggest challenge for LED manufacturers is creating bulbs that mimic conventional ones in shape and light quality. Even now compact fluorescent lamps (CFLs), which use 25 percent of the energy of standard incandescents, were still more versatile and cost-effective than LEDs .But sooner LED will be improved and beat other convensional lighting.
How LEDs Work
When electrical current runs through an LED, the electrons in the current flow into a semiconductor material containing electron "holes" (spaces) waiting to be filled with electrons. When the electrons fill those holes, energy is released as photons, or light that is emitted outward, turning the LED into a lightbulb. In contrast, incandescent bulbs generate light from the electrical resistance of a metal filament. The resistance method requires more electrical energy to heat up the filament to a point that it glows and emits light.
Thursday, August 1, 2013
Wireless Power Transmission is no more a DREAM
Space-Based Solar Power : 144% more powerful than on earth
When you first hear the phrase “Space Based Solar Power” images of a James Bond villain, spring to mind, as he plots to take over the world with his evil scheme of “Space Solar Power”. However, harvesting solar power in space and sending it to Earth as a renewable energy source, is a dream that will soon be realized. So, let’s ask the BIG question - How is this possible? How is this almost science fiction sounding technology becoming a reality?
First of all, let’s start with the definition. Space-based solar power or space solar power is a way to collect the solar energy, from our Sun, before this energy hits the Earth’s surface. The energy is literally captured and collected in space. Not only does the location of where the solar energy collection takes place, make it different from how we collect solar power here on Earth, but the satellites which collect the Sun’s rays are dynamic, they are actually orbiting the Earth. Here on Earth, our method of collecting solar energy is with a physically fixed solar panel, that is normally on the roof of our home or office or fixed to the ground.
Now you are thinking: But what are the benefits of collecting solar power in space versus here on Earth? The World Radiation Centre estimates that rays collected in space are 144% more powerful than those collected on earth. Why? The short answer has two parts:
1. Our atmosphere or ozone layer
2. Our rotating planet
Our ozone layer blocks, or protects, our planet from several forms of radiation. So the radiation received by a satellite in space will have a different radiation profile, a more powerful one, than what we receive here on Earth. Like our planet, the satellites set up in space, to collect solar rays, will orbit the Earth so they can collect sun 24 hours a day. Locally, our solar panels can only collect sun, at most, 12 hours a day. Half the time a space-based collector can. Us earthlings are also challenged with the weather that will reduce our ability to collect the sun, all those rainy day can be so cumbersome. We are also challenged with the varying strength of sun, even on even the brightest days of the year, the strength of the Sun’s rays’ is reduced near sunset and sunrise. The space ray collectors can collect a more uniform strength of sun. So there is a huge benefit to being able to collect solar power from space, it is stronger and there is the ability to collect more of it each day.
So we can see that we can collect the rays with orbiting satellites outfitted with solar panels and we see the benefits to collecting the rays in space. Now, how do we get the energy collected back down to Earth? Now here is where the James Bond stuff comes into play. The solar energy, collected in space, would be converted into electrical energy that would power a microwave emitter and would in turn beam this energy towards the Earth’s surface where a collector, here on Earth, would receive the energy. So now, you are imagining a beam of light hitting the Earth from space, and you are theoretically correct.
Now there are a whole set of issues around how the electricity gets put into the grid, paid for and who owns it, and this is a larger discussion that has a huge political background that we can explore in another column. What we are more interested with in this article is: How does this new way of collecting a renewable resource impact the environment?
The National Security Space Office (NSSO) estimates that, in theory, one kilometer of solar collectors can collect a supply of energy ,on an annual basis, “equal to the energy contained in all of the known recoverable conventional oil reserves on Earth today.”
Wow! But...
The size of a single solar-power satellite, the one that orbits the Earth collecting solar power, would be 15 times the size of the current international space station. What about the size of the collecting station and where would it be housed? The NSSO suggests the collecting station on Earth would be in a desert. The result of the beam on this eco-system is that it would turn into a lush landscape. This sounds great, don’t we want more lush rain forrest like areas in the world? But changing one eco-system changes them all, especially one as large as Sahara. We are all connected and we really cannot predict the ramifications of such a drastic change.
We then need to factor in the production of these big satellites and receiving stations. Are they made out of recycled materials? How many times do we need to send crews up into space to maintain these solar collectors, what debris do we leave in space to do this?
With so many factors still up in the air and the pros and cons so vast, this is a technology that will challenge us all as it finds its place in the future. For now, at least you are in the know as to what this new technology could is, enjoy the current hot discussion going on around this topic!
A Science Fiction concept brought to reality
When you first hear the phrase “Space Based Solar Power” images of a James Bond villain, spring to mind, as he plots to take over the world with his evil scheme of “Space Solar Power”. However, harvesting solar power in space and sending it to Earth as a renewable energy source, is a dream that will soon be realized. So, let’s ask the BIG question - How is this possible? How is this almost science fiction sounding technology becoming a reality?
First of all, let’s start with the definition. Space-based solar power or space solar power is a way to collect the solar energy, from our Sun, before this energy hits the Earth’s surface. The energy is literally captured and collected in space. Not only does the location of where the solar energy collection takes place, make it different from how we collect solar power here on Earth, but the satellites which collect the Sun’s rays are dynamic, they are actually orbiting the Earth. Here on Earth, our method of collecting solar energy is with a physically fixed solar panel, that is normally on the roof of our home or office or fixed to the ground.
Now you are thinking: But what are the benefits of collecting solar power in space versus here on Earth? The World Radiation Centre estimates that rays collected in space are 144% more powerful than those collected on earth. Why? The short answer has two parts:
1. Our atmosphere or ozone layer
2. Our rotating planet
Our ozone layer blocks, or protects, our planet from several forms of radiation. So the radiation received by a satellite in space will have a different radiation profile, a more powerful one, than what we receive here on Earth. Like our planet, the satellites set up in space, to collect solar rays, will orbit the Earth so they can collect sun 24 hours a day. Locally, our solar panels can only collect sun, at most, 12 hours a day. Half the time a space-based collector can. Us earthlings are also challenged with the weather that will reduce our ability to collect the sun, all those rainy day can be so cumbersome. We are also challenged with the varying strength of sun, even on even the brightest days of the year, the strength of the Sun’s rays’ is reduced near sunset and sunrise. The space ray collectors can collect a more uniform strength of sun. So there is a huge benefit to being able to collect solar power from space, it is stronger and there is the ability to collect more of it each day.
So we can see that we can collect the rays with orbiting satellites outfitted with solar panels and we see the benefits to collecting the rays in space. Now, how do we get the energy collected back down to Earth? Now here is where the James Bond stuff comes into play. The solar energy, collected in space, would be converted into electrical energy that would power a microwave emitter and would in turn beam this energy towards the Earth’s surface where a collector, here on Earth, would receive the energy. So now, you are imagining a beam of light hitting the Earth from space, and you are theoretically correct.
Now there are a whole set of issues around how the electricity gets put into the grid, paid for and who owns it, and this is a larger discussion that has a huge political background that we can explore in another column. What we are more interested with in this article is: How does this new way of collecting a renewable resource impact the environment?
The National Security Space Office (NSSO) estimates that, in theory, one kilometer of solar collectors can collect a supply of energy ,on an annual basis, “equal to the energy contained in all of the known recoverable conventional oil reserves on Earth today.”
Wow! But...
The size of a single solar-power satellite, the one that orbits the Earth collecting solar power, would be 15 times the size of the current international space station. What about the size of the collecting station and where would it be housed? The NSSO suggests the collecting station on Earth would be in a desert. The result of the beam on this eco-system is that it would turn into a lush landscape. This sounds great, don’t we want more lush rain forrest like areas in the world? But changing one eco-system changes them all, especially one as large as Sahara. We are all connected and we really cannot predict the ramifications of such a drastic change.
We then need to factor in the production of these big satellites and receiving stations. Are they made out of recycled materials? How many times do we need to send crews up into space to maintain these solar collectors, what debris do we leave in space to do this?
With so many factors still up in the air and the pros and cons so vast, this is a technology that will challenge us all as it finds its place in the future. For now, at least you are in the know as to what this new technology could is, enjoy the current hot discussion going on around this topic!
Space-Based Solar Power is coming very soon.Fukushima has led Japanese to HIT the MOON sooner than ever thought.
— Nuwan Dhanapala (@nuwan2d) December 3, 2013The Concept of "Net Metering"
Net Metering in Sri Lanka
All electricity customers in Sri Lanka now have the opportunity to produce electricity using renewable sources of energy. A customer can "sell" that electricity to the grid at any time of the day.
What is "net" metering?
Imagine your electricity meter is replaced with a two-way meter. The meter will have two registers: the "import" register and the "export" register. You can produce electricity (using a renewable source of energy), and first use that electricity for your own requirements, and send the surplus back to the grid. Such "exported" electricity units will be registered in the "export" register of your meter.
During certain times of the day, your own electricity production may not be adequate for your requirements. Then your consumption will be recorded in the "import" register.
When the electricity meter is read once a month, you will pay only for the difference between the "import" and the "export". If in any month you have exported more than what you imported, your bill will only carry the monthly fixed charge (no charge for the units of electricity), and the excess exported units will be credited to your next month’s bill.
During certain times of the day, your own electricity production may not be adequate for your requirements. Then your consumption will be recorded in the "import" register.
When the electricity meter is read once a month, you will pay only for the difference between the "import" and the "export". If in any month you have exported more than what you imported, your bill will only carry the monthly fixed charge (no charge for the units of electricity), and the excess exported units will be credited to your next month’s bill.
No financial transactions
As the term implies, in "net" metering, there is no "payment" by your electricity supplier for what you produce. LECO or CEB only agrees to let you "bank" your surplus electricity with them, and let you take it back whenever you want, at any time in the future. The transaction is "in kind", not in Rupees and cents. You get effectively paid for at the same rate you pay for your electricity, because you avoid purchasing from your electricity supplier.
You must use only a renewable source of energy to produce electricity. Therefore, power plants run on petrol, diesel, kerosene and gas are not allowed, and they would be too expensive any way. Those who have such oil-burning power plants, are free to use them for their own consumption, but cannot apply for "net" metering to "sell" the surplus to the grid.
You must use only a renewable source of energy to produce electricity. Therefore, power plants run on petrol, diesel, kerosene and gas are not allowed, and they would be too expensive any way. Those who have such oil-burning power plants, are free to use them for their own consumption, but cannot apply for "net" metering to "sell" the surplus to the grid.
Bank your surplus energy with LECO and CEB
LECO/CEB will require certain new protection equipment and a new meter to be fixed, for which there will be a one-time cost. After all, electricity distribution wires were designed to supply electricity to you, and not to let you send electricity on the same wires back to the supplier. However, this thinking has changed over time, and LECO (and CEB) are now providing a facility for you to bank your surplus energy with them, and take them back later on. There is no charge by LECO (or CEB) for banking your surplus energy, but would not want to risk the safety of their workmen in case you send the electricity back when their maintenance staff is working on the line.
The equipment you have to purchase and fix will not allow you to send power back on the line, when the supplier has switched-off the lines for maintenance.
Sri Lanka is among the first few developing countries to introduce "net" metering, and that too free of charge, except for the initial charge for a one-time charge for a new meter and protection equipment. Total flexibility is allowed to the customer to choose the type and size of his renewable energy facility, and the customer is free to switch on and off whenever he likes. LECO (and CEB) would always standby to provide your electricity supply, in case your renewable energy facility goes out of order or if you simply give-up using it. There will obviously be a loss of income to LECO and CEB, which they have obviously resolved to put up with, to support the cause of renewable energy development in Sri Lanka.
In 2007, Sri Lanka produced 40% of her electricity requirements of the grid, using renewable energy, which too places the country high on the world ranking. With the new large coal power plants being built to meet the growing demand at a lower cost, this share of renewable energy may drop to 25% within a decade from now. Sri Lanka’s national energy policy released in 2008 has declared that by 2015, the country would endeavor to achieve a 10% contribution to grid electricity from small non-conventional renewable energy sources. By end 2007, the country has achieved 3.5%, and the net metering facility would certainly help to further improve this renewable energy contribution.
The equipment you have to purchase and fix will not allow you to send power back on the line, when the supplier has switched-off the lines for maintenance.
Sri Lanka is among the first few developing countries to introduce "net" metering, and that too free of charge, except for the initial charge for a one-time charge for a new meter and protection equipment. Total flexibility is allowed to the customer to choose the type and size of his renewable energy facility, and the customer is free to switch on and off whenever he likes. LECO (and CEB) would always standby to provide your electricity supply, in case your renewable energy facility goes out of order or if you simply give-up using it. There will obviously be a loss of income to LECO and CEB, which they have obviously resolved to put up with, to support the cause of renewable energy development in Sri Lanka.
In 2007, Sri Lanka produced 40% of her electricity requirements of the grid, using renewable energy, which too places the country high on the world ranking. With the new large coal power plants being built to meet the growing demand at a lower cost, this share of renewable energy may drop to 25% within a decade from now. Sri Lanka’s national energy policy released in 2008 has declared that by 2015, the country would endeavor to achieve a 10% contribution to grid electricity from small non-conventional renewable energy sources. By end 2007, the country has achieved 3.5%, and the net metering facility would certainly help to further improve this renewable energy contribution.
Monday, March 4, 2013
Light
What human can see around,in other words the reason why man perceive things on his
eyes, is because of light.My intention here is to discuss the properties of light.
What is light made off?
Light is what's called an "electromagnetic wave", just like radio waves, microwaves,
X-ray waves, etc. Electromagnetic waves typically start when an electric charge jiggles
back and forth.
Depending on the "frequency" of the electromagnetic wave, you get different kinds
of waves.For example, radio waves have a pretty low frequency - i.e: the peaks in
a radio wave are pretty far apart. Next comes microwaves, then infrared light.
Next is the visible spectrum where the different colors of light that people can see
(will discuss about Colour, later in this blog), followed by ultraviolet light(see figure 1).
Then waves with higher frequency are called X-rays and still higher are gamma rays -
these have the peaks closest together.
Sometimes you'll hear that light is made of photons. What that means is that when
light is absorbed or emitted, the energy in the wave comes in lumps. The size
of those lumps (or "quanta") of energy depends on the frequency. The higher
the frequency the more energy per photon.
figure 1
Sunday, March 3, 2013
Ice Breaking
Hi all,
I am Nuwan Dhanapala one of who utilised maximum benifit of free education exist in
SriLanka, and currently playing a rolle of an Electrical Engineer in the field of electricity
distribution.
An idea of creating a blogg space came to my mind long time back and couldn't launch
because of laziness,and you only get to know your value,if you share what you have with
others.
Basically, what I am going to publish here might be the answers for some of yours
questions or the parth to find answers,but what I belive always is answers are relative
and human never get satisfied at once.
questions or the parth to find answers,but what I belive always is answers are relative
and human never get satisfied at once.
I must say that, I have no single clue of how to continue this blog,but I know that I have
things to share with others.Therefore i need othes opinions,advices and ideas as well to
continue this job.
OK lets stop BOASTING start POSTING...
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