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Seminar on DSTATCOM
Shunt Connected Controllers at distribution and transmission levels usually fall under two catogories – Static Synchronous Generators (SSG) and Static VAr Compensators (SVC).
A Static Synchronous Generator (SSG) is defined by IEEE as a self-commutated switching power converter supplied from from an appropriate electric energy source and operated to produce a set of adjustable multiphase voltages , which may be coupled to an ac power system for the purpose of exchanging independently controllable real and reactive power. When the active energy source (usually battery bank, Superconducting Magnetic Energy Storage etc) is dispensed with and replaced by a DC Capacitor which can not absorb or deliver real power except for short durations the SVG becomes a Static Synchronous Compensator (STATCOM) . STATCOM has no long term energy support in the DC Side and can not exchange real power with the ac system ; however it can exchange reactive power. Also , in principle, it can exchange harmonic power too. But when a STATCOM is designed to handle reactive power and harmonic currents together it gets a new name – Shunt Active Power Filter. So a STATCOM handles only fundamental reactive power exchange with the ac system.
STATCOMs are employed at distribution and transmission levels – though for different purposes. When a STATCOM is employed at the distribution level or at the load end for power factor improvement and voltage regulation alone it is called DSTATCOM. When it is used to do harmonic filtering in addition or exclusively it is called Active Power Filter. In the transmission system STATCOMs handle only fundamental reactive power and provide voltage support to buses. In addition STATCOMs in transmission system are also used to modulate bus voltages duting transient and dynamic disturbances in order to improve transient stability margins and to damp dynamic oscillations.
IEEE defines the second kind of Shunt Connected Controller called Static VAr Compensator (SVC) as a shunt connected static var generator or absorber whose output is adjusted to exchange capacitive or inductive current so as to maintain or control specific parameters of the electrical power system (typically bus voltage).Thyristor-switched or thyristor-controlled capacitors/inductors and combinations of such equipment with fixed capacitors and inductors come under this.This has been covered in an earlier lecture and this lecture focusses on STACOMs at distribution and transmission levels.
PWM Voltage Source Inverter based Static VAr Compensators (referred to as SVC here onwards) began to be considered a viable alternative to the existing passive shunt compensators and Thyristor Controlled Reactor (TCR ) based compensators from mid-eighties onwards. The disadvantages of capacitor/inductor compensation are well known. TCRs could overcome many of the disadvantages of passive compensators. However they suffered from two major disadvantages ;namely slow response to a VAr command and injection of considerable amount of harmonic currents into the power system which had to be cancelled by special transformers and filtered by heavy passive filters.
It became clear in the early eighties that apart from the mundane job of pumping lagging/leading VArs into the power system at chosen points ,VAr generators can assist in enhancing stability of the power system during large signal and small signal disturbances if only they were faster in the time domain. Also ,they can provide reactive support against a fluctuating load to maintain the bus voltage regulation and to reduce flicker problems,provide reactive support to control bus voltages against sag and swell conditions and provide reactive support to correct the voltage unbalance in the source – if only they were fast enough. PWM STATCOMs covered in this lecture are capable of delivering lagging/leading VArs to a load or to a bus in the power system in a rapidly controlled manner.
High Power STATCOMs of this type essentially consist of a three phase PWM Inverter using GTOs,Thyristors or IGBTs, a D.C. side capacitor which provides the D.C. voltage required by the inverter,filter components to filter out the high frequency components of inverter output voltage,a link inductor which links the inverter output to the a.c supply side,interface magnetics (if required) and the related control blocks. The Inverter generates a three-phase voltage, which is synchronized with the a.c supply ,from the D.C. side capacitor and the link inductance links up this voltage to the a.c source. The current drawn by the Inverter from the a.c supply is controlled to be mainly reactive(leading or lagging as per requirement) with a small active component needed to supply the losses in the Inverter and Link Inductor (and in the magnetics,if any).The D.C. side capacitor voltage is maintained constant( or allowed to vary with a definite relationship maintained between its value and the reactive power to be delivered by the Inverter) by controlling this small active current component. The currents are controlled indirectly by controlling the phase angle of Inverter output Voltage with respect to the a.c side source voltage in the “Synchronous Link Based Control Scheme” whereas they are controlled directly by current feedback in the case of “Current Controlled Scheme”.In the latter case the Inverter will be a Current Regulated one ,i.e. its switches are controlled in such a way that the Inverter delivers a commanded current at its output rather than a commanded voltage (the voltage required to see that the commanded current flows out of Inverter will automatically be synthesized by the Inverter).Current Control Scheme results in a very fast STATCOM which can adjust its reactive output within tens of microseconds of a sudden change in the reactive demand
National Electrical Code (NEC)
National Electrical Code - NEC
National Electrical Code is the United States standard for the installation of electric wiring safely; it is the most approved American national standard. Actually it is a series of codes issued by National Fire Protection Association (NFPA). This NEC consists of 19 code making panels and technical correlating committee. NEC work is sponsored by NFPA. It is formally identified as ANSI/NFPA 70.
This code was published in 1897 and is getting updated every three years. The 2008 code is the most recent version. Most states adopt the most recent edition within a couple of years of its publication. As with all national codes some of the portions or sections are omitted usually, but NEC is the least amended model code
NEC can be accessed to the public as a book in early periods but now available in the electronic version. NEC is composed of introduction, nine chapters. The introduction contains purpose, scope, enforcement and rules or information. These chapters deal with voltages, connections, markings, wiring devices, conductors, cables, cords, switches, heaters etc. In general all the chapters enclose numbered articles, parts, sections (or lists or tables) italicized exceptions, and fine print notes (FPN) -- explanations that are not part of the rules. Each code article is numbered based on the chapter which is in.
For eg; Article 210 addresses branch circuits and receptacles. This says about the minimum number of branches, placement of receptacles etc. NEC also has laws about how many circuits and receptacles are to be placed in a residential dwelling. It has separate law enforcement sections on conduit and cable protection, temperature rating etc
NEC consists of codes covering all the sections in electrical field. So in general NEC is the most accepted and least amended electrical code.
ELECTRICAL SAFETY MEASURES
ELECTRICAL SAFETY MEASURES
We can’t even think of a day with out electricity. It has such relevance in our every day life. We know in earlier periods how miserable were the days with out electricity. It’s an extremely powerful force and if it’s not used properly and if proper safety measures are not taken, electricity would become deadly harmful. So the topic about safety measure is such a way important. Taking proper safety measures will always keep the harm away
It’s important to take apt measures against accidents while working indoor and outdoor. Public utility commission of Ohio offers several tips for keeping safety under all working conditions.
To ensure indoor safety we must make sure that no electric cords or wires are frayed or cracked. If any, remove or replace it in no time. Over loading is another important cause for accidents because it’s really harmful to take large number of appliances from a single outlet, it’s to be avoided. Ensure that electric plugs are fitted properly. While unplugging always pull the plug and not the cord because pulling the cords do harm to all the internal connections and may harm the user. Avoid using extension cords and if necessary relieve suddenly after use. Avoid contact of water from all the electric appliances. Never use any metal pieces to dislodge something from an electrical appliance.
Let’s have a look at the outdoor precautions to be taken. Severe weather conditions may cause live power wires fall on the ground, don’t ever attempt to touch the wire and its surroundings. Inform the police as early as possible if noticed. Use wood ladders around the power lines instead of metal; also keep the ladders at a minimum distance of 10 feet away from the power lines. Make the surroundings of power line free from plants, branches of tree. Don’t use any wet tools. Keep the electric lines far from the reach of children.
Use wires and cables with ISI mark, Use lamp holders with lamp, use appropriate MCB and Use apt rated fuses. While repairing get the certified electrician. If any accident occurs, don’t touch the victim directly. Make him free from electric contact, i.e., to turn off the supply, give him first aid and call for medical assistance. If ant electric device catches fire, don’t try to put out it with water, immediately switch off the supply and use fire extinguisher.
basic electrical engineering rules
BASIC ELECTRICAL RULES
To protect all while working under electric apparatus from hazardous conditions some rules are to be strictly followed. They are made and proposed for the safety of users. These rules are listed under several sections.
Make sure that the equipment used is safe and check its working conditions properly. If the equipment is watered by some means, do avoid contact with it. Use the appliance only for the purpose for which it is made. Before using the device, check whether it has passed the entire requirement prescribed. Avoid direct contact from fuses. The equipments that are made to use in wet conditions may only used in that condition, ensure it. Before using identify its working and disconnecting methods. Equipments with out the mark of manufacturer can’t be used. Maintenances should be done in a proper way. The cases, cables, fuses all should be fixed as prescribed. Another important thing is the equipment should be perfectly grounded and is over current protected. Several different rules are to be used in different working conditions. The devices are to be classified under type, voltage, power rating and several other factors. Replace the fuse only after rectified the mistake of the blown fuse. Avoid using wires with poor insulation. Don’t touch the circuit with fingers. Proper safety measures are to be followed in each case.
electrical engineering basic seminar topics
Mechatronics Engineering
A formal definition of mechatronics is “the synergic integration of mechanics, mechanical engineering, electronics, computer technology and IT to produce enhanced products and systems.
Mechatronics is a vast subject which has deep roots in the fields of mechanical, electronic, computer and control engineering. Mechatronics is exceptionally useful in design engineering to create new products. Actually it is a combination of mechanics, computing, controlling etc. This combination made possible the invention of more versatile systems.
A robot is the typical example for a mechatronic system. It includes all the aspects of above said subjects. The collaboration of mechatronic molecules gives rise to new different formats of designs. Mechatronic is such an advanced field of technology which makes possible new creations with the help of almost all the major branches in technical field. Hybrid systems important to mechatronics include production drives, synergy drives, planetary exploration rovers, automotive subsystems, auto focus cameras, hard drives and CD players.
It has applications on automation and robotics, servo mechanics, sensing and control systems, automotive engineering, biomedical engineering, computer aided design, manufacturing systems etc. So this topic is much relevant to discuss about.
Electrical equipment is an appliance powered by electricity. This includes an enclosure, several electrical components, power switch etc. A machine which is the part of an electrical distribution system can be put under the category of electrical equipment. The components in this include switch board, distribution board, circuit breakers, energy meters, transformers etc
Let’s have a look at some significant electrical equipment. Electrical switch board is a major appliance. It directs electricity from one form to another. These switch boards contain large number of panels and each of it contains switches to redirect electricity. Actually the control of electricity to this switch board is carried out by electrical generators. As the power law defines the amount of power entering and leaving the switch must be equal. So generators make this stable. While going to the technical side of switch boards, it contains bus bars inside the case to isolate the switch board from the connections before it gets opened.
Distribution board is key electrical equipment. The main function of a distribution board is to divide the electric power feed into subsidiary circuits. It provides a safety breaker and fuse for each circuit in a common enclosure and hence the distribution board is sometimes called as power breaker.
An unavoidable part in electrical equipment section is circuit breakers. Basically it is an electric switch. It is designed to protect a device from over current or short circuit. It detects the fault if any and stops the flow of current to it. It incorporates manual as well as automatic control for switching operations. The latter control employs relays and operates only under fault conditions.
Its known to every one, transformer holds the top slot in the priority list. It’s a static piece of apparatus by means of which electric power from one circuit is transformed into electrical power of the same frequency in another circuit. It can raise and lower the voltage according to the need with the increase or decrease in current. The physical basis of a transformer is mutual induction and it works under the principle of Faraday’s laws of electromagnetic induction.
The above explained are some of the main electrical equipments which hold the key place in this section.
ELECTRICAL ENGINEERING
It is commonly known as Electrical & Electronics engineering. Electrical engineering has as much relevance as electricity has in our life. So it is considered as one of the major and basic branches in engineering field. We can’t even think of an earth with out electricity.
At first this branch dealt with electricity, electronics and electromagnetism, now power electronics, power systems, digital signal processing, control systems are all handled by an electrical engineer. The major advancement in this field was emerged by late 19th centaury. By 17th centaury the work on electricity got started. It includes the famous works done by George Ohm on the relationship between current and potential difference, Michael Faraday’s Electromagnetic induction, James Clerk Maxwell’s theory on electricity and electromagnetism. These all made the advancement of an electric era so fast.
Major and noticeable inventions in this field are Cathode Ray Oscilloscope by Karl Ferdinand Baum, Diode by John Fleming, Triode by Robert Von Lieben and Lee Deforest, Albert Hull’s Magnetron which eventually lead to the development of Microwave oven by Percy Spencer. These inventions made our life as wonderful as we wish. We know how well these all take parts in our life.
In the field of education, an electrical engineer covers Maths, Physics, computer science, specific topics in electrical engineering. They should have detailed knowledge in Electrical machines, signal processing, power systems, power electronics, and control systems
An electrical engineer has to work in the development of wide range of technologies. They use to design, test and supervise all electric systems. They are destined to work in electric power stations, telecommunication systems, and satellite communications, in the fields of power generation, transmission and distribution. It includes work on transformers, motors, alternators, generators etc.
Electrical engineer has a key role in the field of space flight. Control system is a major topic in electrical engineering; this plays an exceptionally strong role in space flight. Electronics is the sub discipline of electrical branch. It involves the testing of electric circuits, properties of resistors, capacitors, diodes etc. It deals with the study of radar, commercial circuits, microprocessors and its applications on different fields.
Digital signal processing is an unavoidable section in electrical engineering. It deals with the analysis and manipulation of signals. Another markable feature is in the field of computer technology. This involves the designing of computer and computer systems.
In short, in every walk of our life we can feel the importance of electricity and hence electrical engineering.
electrical engineering basic seminar topics
VARISTORS
The name varistor came from variable resistor. Varistor is a pure electronic component used to protect circuits from transient over voltages making the circuit triggered. The function of a varistor is to provide increased current when voltage becomes excessively high. Varistor is also known as Voltage Dependent Resistor (VDR) since it depends on voltage.
The most common type we are dealing with now days is Metal Oxide Varistor (MOV). It is just like a Unijunction Transistor, since it allows current flow only in one direction. It contains mass of ceramic grains enclosed between two metal plates. The boundary between and its neighbour forms a diode junction. So when a small voltage is applied across the electrodes, only a small current passes due to the reverse break down at the junctions. Similarly when a large voltage is applied, due to thermionic emission large current passes through the junction. This behavior results in nonlinear current voltage characteristic.
Varistor can absorb surge in some ways but to some to extent. A typical surge protector power strip can be made using MOV’s. A varistor provides no equipment protection from inrush surge current. A varistor doesn’t control such events. Varistors have many applications on different electronic circuits. It can replace ordinary resistor in almost all functions, basically it can vary its resistance. So using varistors we can control voltage and current to the circuit. Thus we can protect the circuit from internal damage and severe short circuits.
What is a neural network?
The term neural network refers to be a club of biological neurons. But now this term is referred as artificial neural network which is composed of artificial neurons. So first of a comparison is needed between both the terms.
Biological neural network (BNN) is composed of natural and is connected in central nervous system or peripheral nervous system. They are destined to perform specific functions as ordained. Artificial neural network are fabricated with a group of artificial neurons. The name is so given because we know a neuron is the basic functional unit of our body which is capable of doing specific functions. These artificial ones are used to solve artificial intelligence problems. The artificial neural network (ANN) focuses on the detailed coverage of two types.
In BNN a single neuron is connected to other neurons and finally forms an extensive connection. These connections are called synapses and are connected with axons to dendrites. As such neural networks are extremely complex. Scientists need to melt the properties of BNN artificially in different areas. They ended up in the formation of ANN. The ANN concentrated in the solving of particular assigned tasks. It is successfully applied to speech recognition, face recognition, image analysis, adaptive control, to construct robots etc. Mostly now they are employed in the fields of statistical estimation, optimization and control theory. All neural networks take numeric input and numeric output.
The concept of neural networks emerged in the late 18th century. In the early 1950’s Friedrich Hayek was the one to posit this idea to the world.
The utility of ANN lies in the fact that it can be used to observe variety of functions. It can be used to determine the significance of seating arrangement in a class room. In real life it deals with function approximation, time prediction, blind signal production, data processing etc. Neural network software is used to research, stimulate, develop and apply ANN and BNN. Neural networks, with their remarkable ability to derive meaning from complicated or imprecise data, can be used to extract patterns and detect trends that are too complex to be noticed by either humans or other computer techniques. A neural network is not something that can be categorized in a single feature. It’s a day by growing branch of science. In all the ways above said neural network is a typical notable area that can produce drastic changes in technologies.
ELECTRO DYNAMIC TETHER
Tether means rope or chain used to fasten animals. In the case of space this tether finds application for connecting two space crafts. So tether is a term which needs key relevance that finds application even in space field. Physically a tether is a long flexible cable that connects two masses. When the cable is electrically conductive it is called as electro dynamic tether.
In the early 20th century Giuseppe Colombo came up with an idea of connecting two space crafts by means of some flexible cables. It also needed to be electrically conductive. So as a step forward to this idea NASA launched a shuttle to deploy a satellite on a tether to study the electromagnetic effects of a conducting tether as it passes through Earth’s magnetic fields ad a current was produced in the tether as it passes earth’s magnetic field, acting as an electric generator. This was the actual origin of electro dynamic tether.
There are mainly three types of electro dynamic tether employed systems available depending on the advantages.
1. Electro dynamic tether systems- In this type two heavy masses are separated by means a long flexible extensive electrically conductive cable. This can perform various functions in space craft.
2. In low earth orbit tether can provide electrical power and positioning capability for satellites and space crafts.
3. In the case of long term mission tethers could drastically reduce the amount of fuel needed.
Now tethers are made of electrically conducting materials like aluminium or copper. This provides additional advantages to the tethers. An electro dynamic tether is a device use to convert orbital energy to electrical energy and it works on the principle of electro magnetic induction. This can be used for power generation. Tethers found applications in orbit raising, lowering and debris removal. Another application of tether is artificial gravity inside space crafts.
ELECTRICAL POWERLINE NETWORKING
It is the method normally called home networking through which we are capable of interconnecting computers. This networking uses excited AC wire and power outlets to transmit the desired data to homes and different offices. Powerline networking allows sharing web access, printers, PC drives with all the existing wires, that means no new wires are needed to interconnect. Power line is one of the efficient methods for interconnecting computers. It uses electrical wiring in our house to create a network.
The main and key advantage of powerline networking is the PCs need not be put near the phone outlets instead the devices are connected through electrical output. We can’t start networking just by plugging in. Power line networking is based on Alliance home plug 1.o standard. With this type of networking we can interlink all the devices in our home without interrupting the working of each device.
As said earlier no extra wire is need for this networking. It uses standard plug or outlet to interlink and hence it is possible to access any where at home. It is easy to connect with Ethernet. Ethernet is a standard protocol for transferring data to and fro. Another notable feature is this type of networking provides maximum bandwidth and variable frequency band. This is the cheapest method for connecting different devices locating in various rooms.
IN this type of networking electrical power is transmitted over high voltage lines and distributed in low voltage lines. Proprietary specifications for power line home networking have been developed by a number of different companies within the framework. Power line communication modems are available for the data transfer. So lets conclude power line networking as one of the efficient and fabulous methods to interconnect computers.
What are Electrical Generators?
It is a device that converts mechanical energy into electrical energy. The source of mechanical energy may be a reciprocating pump or turbine. Essentially an electrical generator consists of two parts-magnetic field and conductors.
The energy conversion is based on the principle of production of dynamically induced e.m.f. This dynamically induced e.m.f is produced under Faraday’s laws of Electromagnetic Induction. The e.m.f causes current flow if the circuit is closed. A generator forces electric charge to move to an external circuit, but it doesn’t produce any charge. The charge is present in the windings of wire.
Dynamo was the first electrical generator capable of supplying power to the industry. It uses electromagnetic principles for the conversion of mechanical power in electric current
As described in electrical terms and mechanical terms generator consists of two parts
1) Mechanical-Rotor and Stator
Rotor is the rotating part of motor, dynamo, alternator and generator and a Stator is the stationary part of motor, dynamo, alternator and generator.
2) Electrical-Armature and Field
Armature is the power producing component of motor, dynamo, alternator and generator and Field is the magnetic field component of motor, dynamo, alternator and generator.
Generator uses field coils that require a current flow to be present in the field coils. (Equivalent circuit). Different types of generators now in use are vehicle mount, engine generators, human powered electrical generators etc.
As described above an electrical generator converts mechanical energy into electrical energy. It is a most common which we use frequently. This plays such a major role in electricity production.
electrical engineering basic seminar topics
VACUUM CIRCUIT BREAKER
Circuit breakers are devices which can automatically break a circuit under fault conditions and it can make the circuit manually after the fault. Circuit breakers are classified into different types. One of the main circuit breaker among them is Vacuum circuit breaker. Here vacuum is used to extinct the arc. Arc extinction is the main process of a circuit breaker
Before that, it is needy to explain how an arc is produced. Circuit breaker has two contacts- Fixed and movable, otherwise called as electrodes. Normally the contacts remain closed but if any fault occurs these contacts open automatically and of course can be opened manually.
We know that circuit breakers work under the instructions from relay. When the trip coils from relay energize, circuit breaker identifies fault occurred and hence the contacts are pulled apart. A high intensity current flows through the contacts of the circuit breaker before they are opened by the system. At the same instant contacts begin to separate and causes heavy heat and temperature in between the contacts. This is termed as an arc. This heat is highly dangerous and can cause heavy damage to the whole system. So it has to be extinguished in no time.
Vacuum is having superior qualities over other arc quenching medium. It has high insulating strength. When the contacts are opened in vacuum, the arc is produced in between them. It got extinguishes quickly since the metallic vapours and ions produced during the arc rapidly condense on the surface of the circuit breaker contacts, resulting in quick recovery of dielectric strength.
The contacts of Vacuum circuit breaker and arc shied is mounted inside a vacuum chamber. The chamber is connected to the control mechanism by means of stainless steel bellows. A glass vessel is used as the outer insulating body. This is all about its construction.
Vacuum circuit breaker is really the most reliable one with low cost, no fire hazards, no gas generation, low arc energy, little maintenance and low inertia.
What is an Actuator?
In engineering field actuators have many more applications in different sectors. In this field actuators are used as mechanisms to provide motion and are again used to stop the motion of that particular device. So it is clear that actuator just actuates the motion. May be start or stop, depends on the machine.
In electronics engineering, actuators are subdivisions of transducers. They are used to transform input signal into motion. Normally input signal would be electrical. E.g. electrical motors, pistons, relays, pneumatic actuators, piezo electric actuators etc. Actuators can be sometimes used as hardware components. Different types of actuators are available like plasma actuators, pneumatic actuators, electric actuators, linear actuators.
It’s a type of tool used to put something into automatic action. Actually actuators are used with number of sources. Depending on the type of actuator we are using, different tools will be assisting us to put the device to motion. Mostly they are used in office work area since most of them are used to move valve door in systems.
Sometimes they are used to maneuver certain mechanical devices on work. Depending on the shape and style actuators are divided into different classes. Linear actuators, valve actuators, hydraulic actuators are the best known and used among them. Each of them has assigned functions e.g. hydraulic actuators are used to allow more pressure, size and movement with the object.
All of these different types of actuators are best when knowing what type of motion control you need. They also provide speed, Belt drive, acceleration and accuracy with linear motion No matter what type of actuator is needed, there is a tool that makes it easier to maneuver a certain object or space in your work area.
DIGITAL SIGNAL PROCESSING (DSP)
It’s a major branch of science that deals with the representation of signals as symbols or sequences and after that these signals are getting processed. There are two subfields of processing available- Analog signal processing and Digital signal processing.
This digital signal processing also includes subfields like audio and speech processing, sonar and radar processing, sensor array processing, spectral estimation, statistical signal processing, digital image processing, signal processing for communication systems, biomedical signal processing, seismic signal processing etc. So from the above description it’s clear that DSP is a vast branch in engineering field that requires genuine attention and development.
Generally these processing measures the continuous analog signals and is then converted into digital form by means of an Analog to Digital converter (A-D converter). For certain, the required output would be in Analog form, so the signal is then converted to Analog using Digital to Analog converter (D-A converter). We know that this process is very complex when compared with analog processing and hence error detection and correction methods are used to clarify the process.
The main notable advantage of DSP is that it is less affected to noise and hence non vulnerable. DSP algorithms are carried out in special processors like Digital Signal Processors which is inbuilt in the systems. Since the process is very lengthy and time consuming, we usually undergo the process in this type of processors. DSP’s include microprocessors, digital signal controllers, field programmable gate arrays etc. DSP’s can be implemented using specialized microprocessors like DSP56000, TMS320 and the SHARC.
Usually the digital signals are denoted in time domain, frequency domain, spatial domain etc. With the available characteristics, it is decided that on which domain the signal can be denoted. Sampling is another important point to be specified. Sampling can be done in signal processing during two stages discretization and quantization. In the dicretization stage the space of signals are divided into equivalence classes and quantization is carried out by replacing the signals with representative signals.
DSP has applications in the fields of audio signal processing, audio compression and in the fields as mentioned earlier.
What are Lightning Arresters?
Lightning arresters or surge diverters are used to protect the earth screen and ground wires in an electrical system against direct lightning strokes. They conduct the high voltage surges to the ground without getting affected to the system. The lightning arrestor provides a cone of protection which has a ground radius approximately equal to its height above the ground.
The surge diverters consist of a spark gap in series with a nonlinear resistor. The function of non linear resistor is very important. As the gap sparks over, due to the over voltage, the arc would get short circuited and may cause power flow current in the arrester. Since the characteristic of the resistor is to offer high resistance to high voltage, it prevents the effect of a short circuit. After the surge is over, the resistor offers high resistance to make the gap non-conducting.
One end of the arrestor would be connected to the terminal of the equipment to be protected and other end would be grounded. The length of the spark gap is set in such a way that normal line voltage is enough to cause an arc across the gap but high voltage would break down the air insulation and form an arc.
Different types of surge diverters are available depending on the purpose. Some of them are Rod gap arrester, Horn gap arresters, Multigap arresters, Expulsion type lightning arrester and valve gap arrester. Each of them has variety of range of operating conditions.
What are Acoustic Couplers?
The term acoustic means sound. This is a device used in telecommunication field for coupling electrical signals by acoustical means. Its main working is related to our telephone. Acoustic coupler is a terminal and interface device to link data terminals and radio sets with telephone. Acoustic couplers are used to transmit data over telephone lines using modems. This is a device onto which telephone handset is placed to connect computer to the network, a modem will be also there. Modems that do not use acoustic coupler can some times be called as Direct Connected Modems
The link between the terminals and telephones can be achieved by means of acoustic signals rather than through electrical connections. In 1956 acoustic couplers came into use in our telephone industry till then this industry was a closed system wholly controlled and owned by Bell systems.
At first acoustic couplers were sensitive to external disturbances and noises. Direct electrical connections to telephone networks were made legal in early times. But rapidly preference got secured to the modem connecting method and hence acoustic couplers are used widespread. At times acoustic couplers are no longer used since now a days, telephones can be directly connected to modem instead of connecting to modular telephone connectors. Better connections can be established by avoiding unwanted breakage in signals. Still acoustic coupler modems can be useful in some situations like, in a hotel room where telephone cable is anchored in the walls.
civil engineering seminars topic
CIVIL ENGINEERING SEMINAR TOPICS
ADVANCED CONSTRUCTION MATERIALS
AIR POLLUTION CONTROL
APPLICATION OF INFRARED THERMOGRAPHY IN CONCRETE ENGINEERING
CONFIGWARE
CONSTRUCTION ENGINEERING SYSTEMS
CORROSION OF REINFORCEMENT IN HVFA CONCRETE
DECORATIVE CONCRETES
ENGINEERING BEHAVIOR OF SOILS AND FOUNDATIONS
FATIQUE BEHAVIOUR OF STEEL FIBRE REINFORCED CONCRETE BEAMS
FLUROSCENT MULTILAYER DISC(FMD)
GLOBAL POSITIONING AND GEOGRAPHICAL INFORMATION SYSTEMS APPLICATIONS
HIGH PERFORMANCE CONCRETE
HIGHWAY DESIGN
HIGHWAY SAFETY
MATERIALS OF CONSTRUCTION
MECHANICAL AND ELECTRICAL SYSTEMS IN BUILDINGS
NEW TECHNIQUES OF EROSION CONTROL ON HILL ROADS
OCEANS AS A NON-CONVENTIONAL SOURCE OF ENERGY
PASSIVE SOLAR BUILDINGS
PLASTIC AS SOIL STABILIZER
PRINCIPLES OF ENVIRONMENTAL ENGINEERING
QUANTUM CRYPTOLOGY BECOMES A REALITY
REINFORCED CONCRETE DESIGN
SAFETY IN NUCLEAR POWER PLANTS
SELF COMPACTING CONCRETE
SILICA FUME CONCRETE
SMART MATERIALS AND SMART STRUCTURES
STAMPED CONCRETE
STIRLING ENGINE
STRESS RIBBON BRIDGES
STRUCTURAL ANALYSIS AND DESIGN
STRUCTURAL BEHAVIOR MEASUREMENT
SUPER PLASTICISERS FOR READY MIX CONCRETE PLANTS
TRAFFIC OPERATIONS
TRENCHLESS TECHNOLOGY
ZFS
civil engineering seminars topic
Stamped Concrete
The installation consists of the pressing molds into the concrete while the concrete is still in its plastic state. Color is achieved by using the Color Hardeners or Dry Shakes , Liquid Releases or Powder, Acid Stains or Integral Colors. All these products may be combined to create even more intricate designs.
Decorative Concretes
This Civil Engineering Topic is regarding with the Decorative Conceretes. From the last many years, concrete has been used as a simple, effective & low cost surface for all sorts of areas ranging from car parks to the drive ways to commercial freight yards. However, the one factor you rarely hear being praised is its looks. Techniques to improve the aesthetic appeal of the monolithic concrete pavements have been around since the fifties, notably in North America where concrete is possibly the most popular surfacing for patios, drives and 'yards', and in southern hemisphere, particularly Australia. However, it is the only since the mid 1980s that many of these techniques found their way to the North-west European paving market. Decorative concretes have been used to the dramatic effect in the new structural developments such as Trafford Centre in Birmingham, UK, Basilica of Yamoussoukro on Ivory Coast & the new European Parliament building. Dramatic effects are not only achieved in large structures though. Coloured concrete is just as effectively used in architectural pavements, paving stones and the internal flooring Undoubtedly, the most popular prettifying technique we see in the UK and Ireland and other western countries are Pattern Imprint, sometimes known as ‘Stamped’?’Imprinted' or 'Textured' concrete. From a sluggish start at the back end of the 1980s this technique has slowly but surely grown in popularity and now attracts a reasonable level of the interest, in both residential and commercial markets. In the recent years, refinements and developments of this technique have emerged and we now have stencilling techniques, high-strength textured overlays.Self Compacting Concrete
This Civil Engineering Topics is discussing with the Self Compacting Concrete. Concrete is one of the most used construction material in the world and if correctly composed, it can be vary durable and thus save considerable society resources in the maintenances cost. Self compacting concrete is one of the subjects of concrete technology. The various investigations have been carried out and hence the concrete has been used in practical structures. Here we are providing a brief introduction to self compacting concrete which is also known as SCC is given. The definition and motivation for the development of Self compacting concrete have been discussed. The Self compacting concrete has some advantages over the normal concrete and also some disadvantagesover the normal concrete. An approach has been made to study the various aspects of the Self compacting concrete, such as types of Self compacting concrete, materials used and testing methods, in detail. This Civil Engineering paper also touches the economical considerations, applications and future development of the Self compacting concrete. A concrete that places itself - 'SCC’ A well-proportioned Self compacting concrete can flow under it’s own weight through and around congested reinforcement filling forms completely and producing a void free mass with no vibration and without segregation problems. When large quantity of heavy reinforcement is to be placed in RC member it is difficult to ensure that the formworks get completely filled with concrete that is fully compacted without voids of honeycombs. This problem can now be solved with SCC. SCC is placed or poured in the same as ordinary concrete but without vibration. It is very fluid and can pass around obstructions and fill all the nooks and corners without the risk of either mortar or other ingredients of the concrete separating out. At the same time there are no entrapped air or rock pockets. This type of concrete mixtures does not require any compaction and it saves time labor energy. The surface finish produced by Self compacting concrete is exceptionally good & patching will not necessary. This concept of Self compacting concrete was followed by a major European Research & Development projects. Self compacting concrete has been successfully used in France, Denmark and Netherlands and UK apart from Japan. It is gaining wide acceptability because no noise pollutions there and the construction process is safer and more productive. So ny these we can say that Self compacting concrete is a very good topic in the Civil Engineering.
Advanced Construction Materials
A research on the advanced construction materials has given a push by many factors. In late eighty's, the aerospace industry has seen a steady decline; alternative use of new materials develop for aerospace industry is made possible to construction sector. Exotic materials such as advance polymers & high performance carbon fibre sheeting are researched upon to develop their potential use in the construction of the corrosion free buildings.
The advanced materials are looking on as next generation materials for high techbuildings. Materials that has been researched not only enhances the durability of buildings, but they also have ability to reduce the manpower usage, reduce or eliminating corrosion, and enhancing strength of the structural members. One of new materials which is being rapidly developed & applied is the use of continuous fibres in the construction. Continuous fibres are widely used in the retrofitting and strengthening type of works. Fibres could be impregnat in the resin at factory to produce stiff fibre reinforce polymer plate or they could be soaked in a resin just prior to application at site. Fibre Reinforce Polymer (FRP) utilises the high performance fibres such as the carbon aramid, kevlar and the other glass fibres encapsulated in the resin matrix. This technology has been developed to an alternative to the conventional steel reinforcement for using in the concrete structure primarily for avoiding the corrosion problems associated with the steel.Now, Fibre Reinforce Polymer can be used to increase or enhance flexural & shear strength of the slabs, Columns, Joints and the Slabs.
The advanced materials are looking on as next generation materials for high techbuildings. Materials that has been researched not only enhances the durability of buildings, but they also have ability to reduce the manpower usage, reduce or eliminating corrosion, and enhancing strength of the structural members. One of new materials which is being rapidly developed & applied is the use of continuous fibres in the construction. Continuous fibres are widely used in the retrofitting and strengthening type of works. Fibres could be impregnat in the resin at factory to produce stiff fibre reinforce polymer plate or they could be soaked in a resin just prior to application at site. Fibre Reinforce Polymer (FRP) utilises the high performance fibres such as the carbon aramid, kevlar and the other glass fibres encapsulated in the resin matrix. This technology has been developed to an alternative to the conventional steel reinforcement for using in the concrete structure primarily for avoiding the corrosion problems associated with the steel.Now, Fibre Reinforce Polymer can be used to increase or enhance flexural & shear strength of the slabs, Columns, Joints and the Slabs.
civil engineering seminars topic
Stirling Engine
A Stirling engine, which is a heat engine of external combustion piston engine type whose heat exchange process allows for the near ideal efficiency in the conversion of the heat into the mechanical movement by the following Carnot cycle as closely as is practically possible with the given materials.Stirling engine’s invention is credited to Scottish clergyman Rev. Robert Stirling in 1816 who made significant improvements to the earlier designs and took out the first patent on it. Robert Stirling was later assisted in its development by his engineer brother named James Stirling.
The inventors sought to create a safer alternative to steam engines of the time, whose boilers will often exploded due to the high pressure of steam and the inadequate materials. It will convert any temperature difference directly into the movement.
The Stirling engine will works by repeated heating and cooling of usually sealed amount of working gas, usually air or other gases such as hydrogen or helium. This is accomplished by moving the gas between hot & cold heat exchangers, the hot heat exchanger being a chamber in thermal contact with an external heat source, for e.g. a fuel burner, and the cold heat exchanger being a chamber in the thermal contact with an external heat sink, for e.g. air fins.
The gas will follow the behavior described by gas laws which describe how a gas pressure, temperature and the volume are related. When the gas will be heated, because it is in sealed chamber, the pressure rises and this acts on the power piston to produce a power stroke. When the gas will be cooled, the pressure drops and this means that less work needs to done by the piston to recompress the gas on the return stroke, which will be giving a net gain in the power available on shaft. The working gas flows cyclically between the hot and the cold heat exchangers.
seminars for mechanical engineering
RECENT TRENDS IN AUTOMOBILE ENGINEERING
Use Of Hydrogen as Alternative Fuel To Power Vehicles
ABSTRACT:
Depleting fossil fuel reserves and increasing vehicular emission have forced the attention of various petroleum industries to find and alternate fuel that will power the vehicle in future based on the present day internal design as the deposits of crude oil is expected to last for another 50 years at the minimum utilization level .the proposed fuel should suitably replace the existing fuel and at the same time it should be renewable Hydrogen is one such fuel that has been proposed for the purpose which was suitable for spark ignition engines .hydrogen combines the properties of higher calorific value ,higher velocity of flame propagation ,non toxicity as well as lowest possible emission levels that do not affect the balance of the water of the hydrosphere.
More over the by product of combustion are devoid of carbon dioxide, carbon monoxide which is the major advantage of vehicles powered by fuel cell vehicles.
Fuel cell vehicles represent one of the emerging technologies of the innovation age. An efficient, combustion less, virtually pollution free, free power source capable of being sited down town urban areas or in remote regions, that runs almost silently, and has few moving parts but these vehicles are more reality than dreams. Fuel cells are one of the cleanest and most efficient technologies for generating electricity. In the quest of environment friendly energy generation researchers have come up with comparatively much safer fuels. It is truly a green technology. Fuel cell is the practical, feasible and marketable solution to the energy crisis. The technology is extremely intersecting to people in all walks of life because it offers a mean of making power more efficiently and without pollution.
World automakers seem to believe that low emissions, high efficiency fuel cell will eventually deliver the power and the performance that users expect. Despite difficult technical and market challenges to over come, the latest crop of fuel cell powered concept car appears to exhibit many basic feature required for the success of this concept.
Fuel cell or ZEV’S as they are called are vehicles to look up for as future vehicles. The topic on fuel cell vehicles deals with all the issues and signs related to fuel cell vehicles and their future that is sometimes questioned. However the answers to these questions have been successfully dealt with in the following sub-topics:
INTRODUCTION:-
Another type of Zero-Emission Vehicle is the fuel cell powered vehicle. When the fuel cells are fueled with pure hydrogen, they are considered to be zero emission vehicles. Fuel cells have been used on spacecraft for many years to power electric equipment. These are fueled with liquid hydrogen from the spacecraft's rocket fuel tanks.
What Is a Fuel Cell?
A fuel cell produces electricity directly from the reaction between hydrogen (derived from a hydrogen-containing fuel or produced from the electrolysis of water) and oxygen from the air. Like an internal combustion engine in a conventional car, it turns fuel into power by causing it to release energy. In an internal combustion engine, the fuel burns in tiny explosions that push the pistons up and down. When the fuel burns, it is being oxidized. In a fuel cell, the fuel is also oxidized, but the resulting energy takes the form of electricity .
The Proton Exchange Membrane (PEM) fuel cell is the focus of vehicle-power research. The following are the major different types fuel cells:
- Proton Exchange Membrane (PEM -- sometimes also called "polymer electrolyte membrane") - Considered the leading fuel cell type for passenger car application; operates at relatively low temperatures and has a high power density.
- Phosphoric Acid - The most commercially developed fuel cell; generates electricity at more than 40 percent efficiency.
- Molten Carbonate - Promises high fuel-to-electricity efficiencies and the ability to utilize coal-based fuels.
Solid Oxide - Can reach 60 percent power-generating efficiencies and be employed for large, high powered applications such as industrial generating station
-Alkaline - Used extensively by the space program; can achieve 70 percent power-generating efficiencies, but is considered too costly for transportation applications.
- Direct Methanol - Expected efficiencies of 40 percent with low operating temperatures; able to use hydrogen from methanol without a reformer. (A reformer is a device that produces hydrogen from another fuel like natural gas, methanol, or gasoline for use in a fuel cell.)
PRINCIPLE:
Hydrogen & fuel cell vehicles: Hydrogen is the most abundant element in the universe, but it currently is not be a practical transportation fuel by itself because of storage problems. Hydrogen is normally a gas at room temperature, and storage as a gas requires large containers. Storing it as a liquid requires super-cold temperatures. And because hydrogen is the simplest element, it can even "leak" through the strongest container walls.
One of the most widely suggested sources of electricity for a hybrid electric vehicle is a fuel cell powered by hydrogen. By chemically combining hydrogen and oxygen, rather than "burning a fuel," electricity is created. Water vapor is the by-product.
The fuel cell power system involves three basic steps. First, methanol, natural gas, gasoline or another fuel containing hydrogen is broken down into its component parts to produce hydrogen. This hydrogen is then electrochemically used by the fuel cell.
Fuel cells operate somewhat like a battery. Hydrogen and air are fed to the anode and cathode, respectively, of each cell. These cells are stacked to make up the fuel cell stack. As the hydrogen diffuses through the anode, electrons are stripped off, creating direct current electricity. This electricity can be used directly in a DC electric motor, or it can be converted to alternating current.
To carry gaseous hydrogen on a vehicle, it must be compressed.
When compressed (usually to a pressure of about 3000 pounds per square inch). Hydrogen is stored under great pressure, 3600 and 5000 PSI in the big tanks, 7000 PSI in the smaller distribution tanks.
The other way to provide hydrogen gas to the fuel cell is to store it on the vehicle in liquid form. To make hydrogen liquid, it is chilled and compressed. Liquid hydrogen is very, very cold--more than 423.2 degrees Fairenheit below zero! This super-cold liquid hydrogen is the kind used in space rockets. The containers are able to hold pressure, but they are also insulated to keep the liquid hydrogen from warming up. Warming the liquid, or lowering the pressure, releases gas (like boiling water), and the gas can go to the fuel cell.
NICKEL HYDROGEN:-
Another way to get hydrogen to the fuel cell is to use a "reformer". A reformer is a device that removes the hydrogen from hydrocarbon fuels, like methanol or gasoline. . A reformer turns hydrocarbon or alcohol fuels into hydrogen, which is then fed to the fuel cell. Unfortunately, reformers are not perfect. They generate heat and produce other gases besides hydrogen. They use various devices to try to clean up the hydrogen, but even so, the hydrogen that comes out of them is not pure, and this lowers the efficiency of the fuel cell
When a fuel other than hydrogen is used, the fuel cell is no longer zero-emission, but it
Use of battery unit:-
Small test batteries made under the technology department are stored in one unit to form a single module model of ten batteries.This unit is then used to power the vehicle through the power train and motor as well as the controller which are installed accordingly and this method proves useful in special cases where the fuel cell stack is not work properly due to technical difficulties
The only real problem is the pressure that's involved, and that's not a problem with proper tanking systems and in all these test cases the hydrogen tank did not explode, in spite of being under pressure. the tanks are designed to blow up, not out.
If, for example, that tank back there exploded 90% of the debris would fall within the fence around it.
Hydrogen is a very clean fuel, it would ignite easier than gasoline, but the likelihood of it igniting is still slim . If it did ignite, the flame doesn't put out much heat. Gasoline fires usually consume
Fuel cell design issues:
At the same time many other variables must be juggled, including temperature throughout the cell (which changes and can sometimes destroy a cell through thermal loading), reactant and product levels at various cells. Materials must be chosen to do various tasks which none fill completely. In vehicle usage, many problems are amplified. For instance, cars must be required to start in any weather conditions a person can reasonably expect to encounter: about 80% of the world's car park is legally subject to the requirement of being able to start from sub-zero temperatures. Fuel cells have no difficulty operating in the hottest locations, but the coldest do present a problem
Operational Performance :
Fuel cell vehicles are being developed to meet the performance expectations of today's consumers. These vehicles are expected to be extremely quiet and have very little vibration.
Safety:
The goal is to develop fuel cell vehicles with levels of safety and comfort that are comparable to those of conventional vehicles. If used, high-pressure hydrogen tanks will be designed for maximum safety to avoid rupture. Additionally, manufacturers are perfecting sensors that will immediately detect impact in the case of collision and additional sensors that will detect any leakage from the hydrogen tanks. In both cases, the sensors will instantly shut the valves on the tanks.
Benefits:
Using pure hydrogen to power fuel cell vehicles offers the distinct advantage of zero emissions, but only on the vehicle, not at the hydrogen production source. However, emissions created at a single point of production are often easier to control than those produced by a moving vehicle. A fuel cell vehicle that runs on pure hydrogen produces only water vapor—using any other fuel will produce some carbon dioxide and other emissions, but far less than what is produced by a conventional vehicle.
Fuel cell vehicles are expected to achieve overall energy conversion throughput efficiencies around twice that of today's typical gasoline internal combustion engines. The fuel cell system is being targeted by DOE to achieve 60% efficiency by 2010. Fuel cell vehicles can run on any hydrogen-rich liquid or gas, as long as it is suitably processed. Gasoline is one possibility, but in addition to pure hydrogen, alternative fuels such as ethanol, methanol, natural gas, and propane can also be used.
Why fuel cells for vehicles?
The advantages of fuel cells for transport are both environmental and economic. The only emissions from a fuel cell vehicle come from the generation of hydrogen. These emissions are hardly measurable, making fuel cell vehicles virtually equivalent to zero-emission vehicles. Fuel cell cars will have similar range and performance to cars with internal combustion engines, but the superior energy efficiency of fuel cell engines will bring a significant reduction in carbon dioxide, a greenhouse gas, for every mile travelled. If fuelled directly by hydrogen, there will be no carbon dioxide emissions at all.
Portable fuel cells:
Fuel cells can compete with batteries and generators for portable use, from a few kilowatts to power a mobile home down to a few watts to power a laptop computer. Prototypes have been publicly shown of this type of technology and fuel cell powered mobile phones and laptops are being exhibited at the World Expo 2005 in Japan.
NEW BICYCLE POWERED BY FUEL CELL:
Manhattan Scientifics Inc. has developed a fuel-cell-powered mountain bike that uses hydrogen and air as fuel and emits only water vapor as a waste product. According to its developers, the "Hydrocycle" has a top range of 40 to 60 miles (70-100 km) along a flat surface and can achieve a top speed of 18 mph (30 km/h). Because a fuel cell stack powers its electric motor, the Hydro cycle is extremely quiet and does not need to be recharged like existing electric bicycles; it only needs to be refueled. This would come as a welcome advancement for electric-bike riders frustrated with waiting hours to recharge their battery-powered bicycles
Efficiency of Fuel Cells:
Pollution reduction is one of the primary goals of the fuel cell. By comparing a fuel-cell-powered car to a gasoline-engine-powered car and a battery-powered car, you can see how fuel cells might improve the efficiency of cars today.
Since all three types of cars have many of the same components (tires, transmissions, etc.), we'll ignore that part of the car and compare efficiencies up to the point where mechanical power is generated. Let's start with the fuel-cell car. (All of these efficiencies are approximations, but they should be close enough to make a rough comparison.)
Fuel-Cell-Powered Electric Car:
If the fuel cell is powered with pure hydrogen, it has the potential to be up to 80-percent efficient. That is, it converts 80 percent of the energy content of the hydrogen into electrical energy. But, as we learned in the previous section, hydrogen is difficult to store in a car. When we add a reformer to convert methanol to hydrogen, the overall efficiency drops to about 30 to 40 percent.
We still need to convert the electrical energy into mechanical work. This is accomplished by the electric motor and inverter. A reasonable number for the efficiency of the motor/inverter is about 80 percent. So we have 30- to 40-percent efficiency at converting methanol to electricity, and 80-percent efficiency converting electricity to mechanical power. That gives an overall efficiency of about 24 to 32 percent
TINY FUEL CELL TO POWER SENSORS IN VEHICLES:
A cell phone, for example, needs about 500 watts. The first use will be in sensors for the military.
The prototype micro fuel cell uses an electrochemical process to directly convert energy from hydrogen into electricity. The fuel cell works like a battery, using an anode and cathode, positive and negative electrodes (solid electrical conductors), with an electrolyte. The electrolyte can be made of various materials or solutions. The hydrogen flows into the anode and the molecules are split into protons and electrons. The protons flow through the electrolyte, while the electrons take a different path, creating an electrical current. At the other end of the fuel cell, oxygen is pulled in from the air and flows into the cathode. The hydrogen protons and electrons reunite in the cathode and chemically bond with the oxygen atoms to form water molecules. Theoretically, the only waste product produced by a fuel cell is water. Fuel cells that extract hydrogen from natural gas or another hydrocarbon will emit some carbon dioxide as a byproduct, but in much smaller amounts than those produced by traditional energy source.
Gasoline and Battery Power
Gasoline-Powered Car :
The efficiency of a gasoline-powered car is surprisingly low. All of the heat that comes out as exhaust or goes into the radiator is wasted energy. The engine also uses a lot of energy turning the various pumps, fans and generators that keep it going. So the overall efficiency of an automotive gas engine is about 20 percent. That is, only about 20 percent of the thermal-energy content of the gasoline is converted into mechanical work.
Battery-Powered Electric Car :
This type of car has a fairly high efficiency. The battery is about 90-percent efficient (most batteries generate some heat, or require heating), and the electric motor/inverter is about 80-percent efficient. This gives an overall efficiency of about 72 percent.
But that is not the whole story. The electricity used to power the car had to be generated somewhere. If it was generated at a power plant that used a combustion process (rather than nuclear, hydroelectric, solar or wind), then only about 40 percent of the fuel required by the power plant was converted into electricity. The process of charging the car requires the conversion of alternating current (AC) power to direct current (DC) power. This process has an efficiency of about 90 percent.
So, if we look at the whole cycle, the efficiency of an electric car is 72 percent for the car, 40 percent for the power plant and 90 percent for charging the car. That gives an overall efficiency of 26 percent. The overall efficiency varies considerably depending on what sort of power plant is used. If the electricity for the car is generated by a hydroelectric plant for instance, then it is basically free (we didn't burn any fuel to generate it), and the efficiency of the electric car is about 65 percent.
Surprised?
Maybe you are surprised by how close these three technologies are. This exercise points out the importance of considering the whole system, not just the car. We could even go a step further and ask what the efficiency of producing gasoline, methanol or coal is.
Efficiency is not the only consideration, however. People will not drive a car just because it is the most efficient if it makes them change their behavior. They are concerned about many other issues as well. They want to know:
Is the car quick and easy to refuel?
Can it travel a good distance before refueling?
Is it as fast as the other cars on the road?
How much pollution does it produce?
Fuel cell cars are a long way off:
Hybrid cars already exist as commercial products and are available to cut pollution now. On the other hand, fuel-cell cars are expected on the same schedule as NASA's manned trip to Mars—and have about the same level of likelihood
Hydrogen fuel cells cost more: Hydrogen fuel cells in vehicles are about twice as efficient as internal-combustion engines; however, hydrogen fuel cell costs are nearly 100 times as much per unit of power produced.
Hydrogen fuel cells are dirtier:- Fuel-cell cars emit only water vapor and heat, but the creation of the hydrogen fuel (via burning coal, for example) can be responsible for more overall greenhouse gas emissions than conventional internal combustion engines.
Hydrogen fuel is harder to transport:
Moving large volumes of hydrogen gas requires compressing it. Hydrogen compression rates mean that 15 trucks are required to power the same number of cars that could be served by a single gasoline tanker. Liquid hydrogen would require less (about three trucks), but would require substantially more effort and energy to liquefy.
Hydrogen is much more dangerous:-As dangerous as a leak of natural gas is, a hydrogen leak is worse because hydrogen ignites at a wider range of concentrations and requires less energy to ignite. And hydrogen burns invisibly. "It's scary—you cannot see the flame.”
CONCLUSION: -
We have succesfully studied the various technicialities and the experimental procedures carried out by the various automobile companies and their respective research and development departments in depth which do provide a ray of hope .the practical implementation being’s dependancy on oil reserves and their rising costs and their by stabilise the economy for the common man and hence make the environment polution free which is the ultimate goal
“Save environment save world”
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