Different method for correction of power factor

Losses In Transformer

Losses In Transformer

 An electrical transformer is an static device, hence mechanical losses (like windage or friction losses) are absent in it. A transformer only consists of electrical losses (iron losses and copper losses). Transformer losses are similar to losses in a DC machine, except that transformers do not have mechanical losses.
Losses in transformer are explained below -

(I) Core Losses Or Iron Losses

Eddy current loss and hysteresis loss depend upon the magnetic properties of the material used for the construction of core. Hence these losses are also known ascore losses or iron losses.

§  Hysteresis loss in transformer: Hysteresis loss is due to reversal of magnetization in the transformer core. This loss depends upon the volume and grade of the iron, frequency of magnetic reversals and value of flux density. It can be given by, Steinmetz formula:
W_h= ηB_max^1.6fV (watts)       where,   η = Steinmetz hysteresis constant
                                                     V = volume of the core in m³

§  Eddy current loss in transformer: In transformer, AC current is supplied to the primary winding which sets up alternating magnetizing flux. When this flux links with secondary winding, it produces induced emf in it. But some part of this flux also gets linked with other conducting parts like steel core or iron body or the transformer, which will result in induced emf in those parts, causing small circulating current in them. This current is called as eddy current. Due to these eddy currents, some energy will be dissipated in the form of heat.

 (Ii) Copper Loss In Transformer

Copper loss is due to ohmic resistance of the transformer windings.  Copper loss for the primary winding is I₁²R₁ and for secondary winding is I₂²R₂. Where, I₁ and I₂ are current in primary and secondary winding respectively, R₁ and R₂ are the resistances of primary and secondary winding respectively. It is clear that Cu loss is proportional to square of the current, and current depends on the load. Hence copper loss in transformer varies with the load.

Efficiency of Transformer

Just like any other electrical machine, efficiency of a transformer can be defined as the output power divided by the input power. That is  efficiency = output / input .Transformers are the most highly efficient electrical devices. Most of the transformers have full load efficiency between 95% to 98.5% . As a transformer being highly efficient, output and input are having nearly same value, and hence it is impractical to measure the efficiency of transformer by using output / input. A better method to find efficiency of a transformer is using, 

efficiency = (input - losses) / input = 1 - (losses / input).

Condition For Maximum Efficiency

Let,Copper loss = I₁ ²R₁ & Iron loss = Wi 

Hence, efficiency of a transformer will be maximum when copper loss and iron losses are equal.
         That is Copper loss = Iron loss.

Clean Solar Power to Replace Fossil Fuel

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India has recently stepped it up in terms of the government’s support of renewable energy through its efforts in moving from coal powered railways to clean solar panels for electricity and fuel consumption.

The Indian Railways is one of the largest railway systems in the world,  requires massive energy expenditures – specifically 17.5 kWh of electricity per year, and over 90,000 liters of diesel.

Fuel bills are actually the 2nd largest expense of the Indian Railways. With rising prices of fuel imports, the Indian government has began focusing on other forms of energy to power the coaches, specifically solar energy.

Recently, the first solar powered coach was tested, which is a non-airconditioned coach with solar panels installed on its rooftop. The Rewari-Sitapur passenger train was able to generate 17 kWh for an entire day, which was enough to cover only the lighting load of the coach.

Two other coaches have been fitted with solar panels, but are yet to begin their testing stage. These said coaches belong to 2 narrow-gauge trains for the Pathankot-Jogindernagar route in the Kangra Valley and the Kalka-Shimla section.

This massive project and potential move to clean energy is touted to solve two major problems faced by the IR today: rising energy prices and the threats to environment caused by the massive use of fossil fuels. Ideally, the trains will still be powered by traditional diesel-run engines, but the lighting of the passenger coaches will utilize solar energy.

According to a Northern Railway official, there is a total of 40 square meter of space on a typical coach rooftop. The said coach was fitted with 12 solar panels over 24 square meters, but the remaining 16 square meters can still accommodate 6 more panels for more energy production.

Officials say that India has a huge potential for solar power, and that the installation of solar panels are not limited to the train’s rooftops, but can also include those of the railway’s buildings to provide renewable energy for its infrastructure.

The typical cost for fitting panels on one coach is Rs 3.90 lakh, and its return on investment per year is Rs 1.24 lakh. The potential savings of millions of dollars can also include that of foreign exchange reserves in terms of diesel imports. Aside from solar power’s obvious economic benefits for the IR, the use of clean solar power also reduces their emission of carbon dioxide by over 200 tonnes in a year.

Currently, the Indian government is planning to create a solar policy that would lead the way to the production of 1000 megawatts of solar power in the next 5 years. The main aim of the said policy states that by the year 2020, the IR’s renewable energy production will be able to provide at least 10% of the entire enterprise’s energy consumption need.

Today, the project is aimed at a few rooftops lighting up a few non-airconditioned coaches. Future testing is still needed to understand the economics of the proposal before it is implemented on a larger scale. So far, results have been promising and further positive data might just lead the Indian Railways to utilize the use of clean solar energy for all of its coaches.

Wireless energy transmission

Wireless energy generation in space is one step closer to becoming a feasible delivery source of power following a new experiment that transmitted electricity through microwaves.

The Japan Aerospace Exploration Agency (Jaxa) conducted the research, which sent 1.8 kilowatts of electricity 170 feet through the air, in the form of microwave radiation. The beam was transmitted with a great degree of accuracy, showing the technique may be used on a larger scale.

Solar energy might, one day, be collected by massive solar panels in space, and the energy generated from the systems could be sent to Earth in the form of microwaves. Such networks for generating electricity in space would have some advantages over ground-based systems. Solar collectors in space would not be subject to the cycles of day or night, or cloudy conditions.

"This was the first time anyone has managed to send a high output of nearly 2 kilowatts of electric power via microwaves to a small target, using a delicate directivity control device," a Jaxa spokesman said.

Engineers at Jaxa have spent years researching new technologies to deliver energy from space-based solar collectors down to our home planet. Solar cells commonly power satellites, space probes, and the International Space Station. However, delivering that power to Earth in an economical manner is still a challenge facing developers.

Current plans to develop an orbiting energy generation system involve sending satellites into geostationary orbits more than 22,000 miles above the Earth. The satellites would require large solar panels. Challenges facing engineers include launching these massive solar collectors that high above the Earth, and maintaining them once they are in space. Because of these issues, Jaxa engineers believe that a full network to generate electricity in space will not be available until sometime in the 2040's.

Japan is dependent on imports for near all of its energy needs, feeding a desire to develop their own systems. The nation had utilized nuclear reactors to generate electricity, but those plants shut down in the wake of the 2011 Fukushima disaster.

Mitsubishi Heavy Industries recently announced its researchers have successfully transmitted around 10 kilowatts of electricity to a receiver located more than 1,600 feet.

The idea of producing energy in space and sending it to Earth for use has been studied by American researchers for more than 50 years.

Additional uses for the transmitters could include charging electric cars, or sending electricity to remote regions in the wake of natural and man made disasters. Future development of the current system could produce a device capable of transmitting and receiving energy from ocean platforms, far from the nearest coast.

(Organic Photovoltaics)OPV Cell

This is a model of a generator being developed by the Georgia Institute of Technology that looks to take advantage of natural air movements in hot areas. When the sun’s heat hits the ground, a layer of hot air forms at ground level. If that ground-level air is hotter than the air above, it can create upwardly moving whirlwind. In nature, this columnar vortex phenomenon creates “dust devils,” or spinning whirlwinds that lift dirt off the ground. In the device, hot air rises through the turbine, generating electricity.

Features of OPV cell
The most unique aspect of the OPV cell devise is the transparent conductive electrode. This allows the light to react with the active materials inside and create the electricity. Now graphene/polymer sheets are used to create thick arrays of flexible OPV cells and they are used to convert solar radiation into electricity providing cheap solar power.
New OPV design:
Now a research team under the guidance of Chongwu Zhou, Professor of Electrical Engineering, USC Viterbi School of Engineering has put forward the theory that the graphene – in its form as atom-thick carbon atom sheets and then attached to very flexible polymer sheets with thermo-plastic layer protection will be incorporated into the OPV cells. By chemical vapour deposition, quality graphene can now be produced in sufficient quantities also.
Differences between silicon cells and graphene OPV cells:
The traditional silicon solar cells are more efficient as 14 watts of power will be generated from 1000 watts of sunlight where as only 1.3 watts of power can be generated from a graphene OPV cell. But these OPV cells more than compensate by having more advantages like physical flexibility and costing less.
More economical in the long run:
According to a team member, it may be one day possible to run printing presses with these economically priced OPVs covering extensive areas very much like printing newspapers. In Gomez’ words – “They could be hung as curtains in homes or even made into fabric and be worn as power generating clothing…. imagine people powering their cellular phone or music/video device while jogging in the sun.”
Advantages of OPVs:

The flexibility of OPVs gives these cells additional advantage by being operational after repeated bending unlike the Indium-Tin-Oxide cells. Low cost, conductivity, stability, electrode/organic film compatibility, and easy availability along with flexibility give graphene OPV cell a decidedly added advantage over other solar cells.

This is a model of a generator being developed by the Georgia Institute of Technology that looks to take advantage of natural air movements in hot areas. When the sun’s heat hits the ground, a layer of hot air forms at ground level. If that ground-level air is hotter than the air above, it can create upwardly moving whirlwind. In nature, this columnar vortex phenomenon creates “dust devils,” or spinning whirlwinds that lift dirt off the ground. In the device, hot air rises through the turbine, generating electricity.

how power coal fired plant work

A power station is really a machine that extracts energy from a fuel. Some power stations burn fossil fuels such as coal, oil, or gas.Nuclear power stations produce energy by splitting apart atoms of heavy materials such as uranium and plutonium. The heatproduced is used to convert water into steam at high pressure. This steam turns a windmill-like device called a turbine connected to an electricity generator. Extracting heat from a fuel takes place over a number of stages and some energy is wasted at each stage. That means power plants are not very efficient: in a typical plant running on coal, oil, or gas, only about 30–40 percent of the energy locked inside the fuel is converted to electricity and the rest is wasted.

Power station transformers                                    Transmission line

1. Fuel: The energy that finds its way into your TV,computer, or toaster starts off as fuel loaded into a power plant. Some power plants run on coal, while others use oil, natural gas, or methane gas from decomposing rubbish.
2. Furnace: The fuel is burned in a giant furnace to release heat energy.
3. Boiler: In the boiler, heat from the furnace flows around pipes full of cold water. The heat boils the water and turns it into steam.
4. Turbine: The steam flows at high-pressure around a wheel that's a bit like a windmill made of tightly packed metal blades. The blades start turning as the steam flows past. Known as a steam turbine, this device is designed to convert the steam's energy into kinetic energy (the energy of something moving). For the turbine to work efficiently, heat must enter it at a really high temperature and pressure and leave at as low a temperature and pressure as possible.
5. Cooling tower: The giant, jug-shaped cooling towers you see at old power plants make the turbine more efficient. Boiling hot water from the steam turbine is cooled in a heat exchanger called a condenser. Then it's sprayed into the giant cooling towers and pumped back for reuse. Most of the water condenses on the walls of the towers and drips back down again. Only a small amount of the water used escapes as steam from the towers themselves, but huge amounts of heat and energy are lost.
6. Generator: The turbine is linked by an axle to a generator, so the generator spins around with the turbine blades. As it spins, the generator uses the kinetic energy from the turbine to make electricity.
7. Electricity cables: The electricity travels out of the generator to a transformer nearby.
8. Step-up transformer: Electricity loses some of its energy as it travels down wire cables, but high-voltage electricity loses less energy than low-voltage electricity. So the electricity generated in the plant is stepped-up (boosted) to a very high voltage as it leaves the power plant.
9. Pylons: Hugh metal towers carry electricity at extremely high voltages, along overhead cables, to wherever it is needed.
10. Step-down transformer: Once the electricity reaches its destination, another transformer converts the electricity back to a lower voltage safe for homes to use.
11. Homes: Electricity flows into homes through underground cables.
12. Appliances: Electricity flows all round your home to outlets on the wall. When you plug in a television or other appliance, it could be making a very indirect connection to a piece of coal hundreds of miles away!