Dynamic Voltage Restorer (DVR)

Voltage variations are a nightmare for the industries like Semiconductor fabrication plants, Paper mills, Food processing plants and, automotive assembly plants etc. Fast variation in source voltage can affect the overall performance of the industry and also cause damage to critical loads in these industries resulting in great financial loss. The most common disturbances that occur in the source voltage are voltage sags or swells that can be due to disturbances in the transmission line or system, adjacent feeder faults and Fuse or breaker operation. Voltage sags of even 10% lasting for 5-10 cycles can result in costly damage in critical loads and heavy machineries in an industry. The voltage sags can be symmetrical faults in which negative and zero sequence components are also present.

Presence of uncompensated nonlinear loads in the distribution system can cause harmonic components in the supply voltages which are extremely dangerous. To mitigate the problems caused by poor quality of power supply, series connected compensators are used. These compensators are called Dynamic Voltage Restorer (DVR), as their primary application is to compensate for voltage sags and swells. Their configuration is similar to that of SSSC (Static Synchronous Series Compensator). However, the control techniques are different. A DVR is expected to respond fast (less than ¼ cycles) and thus employs PWM converts (Pulse-width modulation converts) using IGBT (Insulated gate bipolar transistor) or IGCT (Integrated Gate-Commutated Thyristor) device.

A DVR has to supply energy to the load during the voltage sags. If a DVR has to supply active power over longer periods, it is convenient to provide a shunt converter that is connected to the DVR on the DC side. As a matter of fact one could envisage a combination of DSTATCOM (Distribution Static Compensator) and DVR connected on the DC side to compensate for both load and supply voltage variations.  The combined compensator is termed as Unified Power Quality Conditioner (UPQC) which has similar to UPFC (Unified Power Flow Controller). However the control objectives are different.

The DVR was first installed on Duke Power System in USA in August 1996, with a rating of 2MVA with 660 kJ of energy storage capacity, it is capable of compensating 50% voltage sag for a period of 0.5 second (30 cycles). It was installed to protect an automated yarn manufacturing and rug weaving facility. Since then, several DVRs have been installed to protect microprocessor fabrication plants, paper mills etc. typically, DVRs are made of modular design with a module rating of 2 MVA or 5 MVA. They have been installed in substations of voltage rating from 11 kV to 66 kV.

VACUUM CIRCUIT BREAKER

VACUUM CIRCUIT BREAKERS

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?

Actuator is a typical mechanical device used to move or control a mechanism or a system. This device gains energy for its working from air, electricity or liquid and then converts it into some kind of motion.

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.

What are Lightning Arresters?

LIGHTNING ARRESTER

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?

ACOUSTIC COUPLER

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.

VARISTORS

What is a VARISTOR?

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?

What are NEURAL NETWORKS?

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.

ELECTRICAL POWERLINE NETWORKING

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.

Electrical Seminar Topics

Electrical Engineering Seminar Topics

electricalseminartopics.blogspot.com basically provides a place for all latest info about Electrical Seminar Topics including Engineering Seminar topics and the reviews of those topics too.One must checkout for latest Technical Seminar Topics including Engineering Seminar topics,Engineering seminars,Electrical Seminar Topics and the reviews of those topics.

If you want a Technical seminar topic some times you have to search it in different places.And if you need to select one Engineering seminar topic you have to search a lot in the internet or the related books. electricalseminartopics.blogspot.com can help you a lot or it.The trend in the seminar topics are changing in these days.We are also trying to make this task as much simple. It can however sometimes be hard to find the things that you want for your technical seminar and this is where you can customizations comes in. Our site has a lot of information for the people who need the Engineering seminars. Not only do we have everything you want for your seminar topics, including Electrical topics, but we also have a lot of technical reviews about different technical topics. As most Engineering seminars are based on the Technical topics you will also find a lot of useful stuff for your engineering seminar using this site. If that was not enough you can search in the side and top links.They also have different seminar topics available for your Technical seminar and they are organized in a way that make sit easy for you to find the Engineering seminar you are looking for.

We are one of the Largest and Most reliable Web-Portal for Technical seminars, Engineering seminars, Mechanical Seminars

Some Technical seminar topics available are:EUV Lithography, Magnetic amplifiers, Nanotechnology,and the topics from the Mechanical Engineering, Electrical engineering, Computer Engineering, Civil Engineering, Electronics Engineering.

It has the largest collection of Engineering Seminar topics. This site contains the largest collections of seminartopics so that you can go and make your seminars more creative and attractive with the whole new wonderful seminar topics. Also all types of new technical topics are reviewed.
like many others, found myself in the need for Technical topics and that’s when the internet comes in hand. A person who is very active always come back looking for more engineering seminars that suits their needs. Fortunetely, these sites usually have their seminars divided into categories by the branch of the Engineering, rescent technical topics and so on.

It is an informative & useful site for all kinds of seminar lovers. It has quality Technical seminars & a variety of categories to choose from. I think it should be recommended to all IT geeks.

Very rarely you come across an IT site, which caters to the industries, really great useful. Real fun to have access to all seminars of various branches in one site.

One can easily download Technical seminars in your computer using this site. You could get all latest technical seminar topics here since they are updated daily.
Thus it is recommended to all those who want to experience first hand information on Technical seminar topics on varied topics.