Valve Regulated Lead Acid (VRLA) Batteries Advantage:

What is Batteries-

A container consisting of one or more cells, in which chemical energy is converted into electricity and used as a source of power.

Types of Batteries:-

Nickel Cadmium (NiCd) — mature and well understood but relatively low in energy density. The NiCd is used where long life, high discharge rate and economical price are important. Main applications are two-way radios, biomedical equipment, professional video cameras and power tools. The NiCd contains toxic metals and is environmentally unfriendly.

Nickel-Metal Hydride (NiMH) — has a higher energy density compared to the NiCd at the expense of reduced cycle life. NiMH contains no toxic metals. Applications include mobile phones and laptop computers.

Lead Acid — most economical for larger power applications where weight is of little concern. The lead acid battery is the preferred choice for hospital equipment, wheelchairs, emergency lighting and UPS systems.

Lithium Ion (Li‑ion) — fastest growing battery system. Li‑ion is used where high-energy density and lightweight is of prime importance. The technology is fragile and a protection circuit is required to assure safety. Applications include notebook computers and cellular phones.

Lithium Ion Polymer (Li‑ion polymer) — offers the attributes of the Li-ion in ultra-slim geometry and simplified packaging. Main applications are mobile phones.

Valve Regulated Lead Acid (VRLA) Batteries are popularly termed as maintenance free lead acid batteries. Each cell in VRLA battery will have a value (automating operating) to allow the gas to escape if developed by the over charging the cells and to hinder the entrance of oxygen from the air into the cell

These VRLA batteries are also called sealed lead acid batteries and also recombinant batteries. Oxygen which evolve during discharging at the positive plate of the battery recombine with the hydrogen which  evolve at the negative plate of the cell to from water. This results in prevention of the water loss and unlike flooded batteries water is not needed to be added periodically. The valve present in VRLA cell acts as a safety valve which opens when the concentration of hydrogen gas inside the battery increases dangerously high. Some of the advantages of VRLA cell is listed below:

Advantages:

• VRLA battery is maintenance free and no periodic water refilling is not required
• Reduced demand on ventilation
• The capacity range of VRLA battery is high (12000 Ah)
• VRLA batteries will have longer life. Life span of this batteries will be around 10 years
• Feasibility for float charge operation with the same voltage of the cells, to continue in using existing charging equipment
• VRLA batteries are economical

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Electrical Engineering Job Opportunites

Electrical Job Opportunities:

Energy is an essential requirement of human life. For any country's development electrical power plays a significant role. Requirement of the electrical energy increases day by day and expansion of electrical industry is in a rapid pace.

With the increase in the demand for electricity. New generation units should be set up. This leads to increase in the scope of transmission and distribution which results in increase in the requirement of the skilled electrical engineers every year.

Civil, Mechanical and Electrical disciplines are considered as mother of all Engineering disciplines. All advanced engineering fields emerged from these core engineering fields. Both in Government and in private sector the requirements and job opportunities for the skilled man power is enormous. Lot of job opportunities will be available in PSUs such as NTPC, BHEL, HAL, ONGC, IOCL and pay will be in par with the private sector.

Electrical Engineering is one of the good disciplines to choose which provides lot more scope to learn and wide job markets after the completion of the course.

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Industrial training

Industrial training Importance in Graduation:

Learning from practical observation is much more efficient than learning theory. However learning theory is the fundamental step to build the concept and learning about the applications of what we learned will be the takeoff point.

Technology what we learned in graduation college will be different from the technology what industry using in current day. Syllabus in graduation cannot changed dynamically to suit the industry as the principles and concepts what we learn in colleges are like small foot steps at our early stage of life. We cannot ignore the very basics of the subject. But there is a gap between the industry needs and the fresh graduates coming out for job market. How to fill the gap?

Industrial training is the tool to learn the industry standards during vacations of our colleges. Once in my college days i planned to prepare technical paper on "Energy Management In Thermal Power Plant".For case study i took permission and visited 1260MW thermal power plant. I have seen the dynamic operation of thermal power plant in real. For calculating the energy of each auxiliary component i went around the plant and took the readings. I was introduced to new technologies such as DCS, SCADA, and automation in thermal power plants, VFDs.. and many more. It widened my level of understanding. Same experience was encountered when visited 400kV Power Grid Substation.

Few days of Industrial training will not give you everything but at least make you feel the difference between College and Industry, helps to understand the industrial standards and technologies used.. Attend any training if you get an opportunity or at least plan for industrial visits. Many companies provide training for graduates contact them and approach through your college administration.

This is a piece of advice give by your senior fellow to my beloved juniors.

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How to Prepare Technical Paper for Presentation (TPP)

Technical papers preparation:

How to prepare a technical paper for paper presentation? What should be the topic of the paper for presentation? What are the resources available for preparing a technical paper? These are some of the questions when you want to start preparing a technical paper when you are a beginner.

What is Paper Presentation?

Paper presentation is the abstract of the work which you have done. The ideas what you learned, observed and discovered when you are working on a particular topic is kept on a paper.

Different Types of Papers:

Technical papers are of three types

1.      Informative

2.      Modeling and Simulation

3.      Design and Manufacture

Informative: This type of papers will explain about the general information available. For eg: Consider latest trends and technologies used in Wind Power Generation. You can collect the information from different sources and organize them accordingly and can give your suggestions, comments on the topic and can make a paper.Technical papers of this type will be given less importance than the others because the direct work involvement which you do is less. However if you add a case study of your own then the quality of the paper will be improved. For eg: Energy Conservation or Audit, you do a case study for your University or big township and give your suggestions.

Modeling and Simulation: Many software tools available for simulation and carryout the studies and before designing simulation tests will be carried out  to study the design. Simulation tests will also be carried out for existing system to determine who it behaves during different operating conditions. Choose some IEEE or other journal technical papers, pick up the topic which will suit you the best. Model the system and try to simulate in different software tools (MATLAB,PSCAD, ETAP,EMTP,PSPICE..) and if possible do the experiment in your lab and analyse the results.

Design and Manufacture: This type of papers explains about designing and manufacturing an equipment. It explains about what are your requirements, who you design the equipment and manufacture it. What is the end result. For eg: you can take up designing SMPS based on your requirement and manufacture it accordingly.

Final Advice: Refer International Journals and Magazines and choose your topic. Do something different from the parent paper (what you taken up as reference). All the Best!

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METHODS OF PRODUCING VOLTAGE

METHODS OF PRODUCING VOLTAGE (ELECTRICITY)

This section provides information on the following methods of producing

·         electricity:

·         Electrochemistry

·         Static (friction)

·         Induction (magnetism)

·         Piezoelectric (pressure)

·         Thermal (heat)

·         Light

·         Thermionic emission

EO 1.5 DESCRIBE how the following methods produce a voltage:

a. Electrochemistry

b. Static electricity

c. Magnetic induction

d. Piezoelectric effect

e. Thermoelectricity

f. Photoelectric effect

g. Thermionic emission

Electrochemistry-

Chemicals can be combined with certain metals to cause a chemical reaction that will transfer electrons to produce electrical energy. This process works on the electrochemistry principle. One example of this principle is the voltaic chemical cell, shown in Figure 11. A chemical reaction produces and maintains opposite charges on two dissimilar metals that serve as the positive and negative terminals. The metals are in contact with an electrolyte solution. Connecting together more than one of these cells will produce a battery.

Static Electricity-

Atoms with the proper number of electrons in orbit around them are in a neutral state, or have a "zero charge." A body of matter consisting of these atoms will neither attract nor repel other matter that is in its vicinity. If electrons are removed from the atoms in this body of matter, as happens due to friction when one rubs a glass rod with a silk cloth, it will become electrically positive as shown in Figure 12. If this body of matter (e.g., glass rod) comes near, but not in contact with, another body having a normal charge, an electric force is exerted between them because of their unequal charges. The existence of this force is referred to as static electricity or electrostatic force.

Magnetic Induction-

A generator is a machine that converts mechanical energy into electrical energy by using the principle of magnetic induction. Magnetic induction is used to produce a voltage by rotating coils of wire through a stationary magnetic field or by rotating a magnetic field through stationary coils of wire. This is one of the most useful and wide l yem ployed applications of producing vast quantities of electric power. Magnetic induction will be studied in more detail in the next two chapters "Magnetism," and "Magnetic Circuits."

Piezoelectric Effect

By applying pressure to certain crystals (such as quartz or Rochelle salts) or certain ceramics (like barium titanate), electrons can be driven out of orbit in the direction of the force. Electrons leave one side of the material and accumulate on the other side, building up positive and negative charges on opposite sides, as shown in Figure 14. When the pressure is released, the electrons return to their orbits. Some materials will react to bending pressure, while others will respond to twisting pressure. This generation of voltage is known as the piezoelectric effect. If external wires are connected while pressure and voltage are present, electrons will flow and current will be produced. If the pressure is held constant, the current will flow until the potential difference is equalized. When the force is removed, the material is decompressed and immediately causes an electric force in the opposite direction. The power capacity of these materials is extremely small. However, these materials are very useful because of their extreme sensitivity to changes of mechanical force.

Thermoelectricity-

Some materials readily give up their electrons and others readily accept electrons. For example, when two dissimilar metals like copper and zinc are joined together, a transfer of electrons can take place. Electrons will leave the copper atoms and enter the zinc atoms. The zinc gets a surplus of electrons and becomes negatively charged. The copper loses electrons and takes on a positive charge. This creates a voltage potential across the junction of the two metals. The heat energy of normal room temperature is enough to make them release and gain electrons, causing a measurable voltage potential. As more heat energy is applied to the junction, more electrons are released, and the voltage potential becomes greater, as shown in Figure 15. When heat is removed and the junction cools, the charges will dissipate and the voltage potential will decrease. This process is called thermoelectricity. A device like this is generally referred to as a "thermocouple."

Thermionic Emission-

A thermionic energy converter is a device consisting of two electrodes placed near one another in a vacuum. One electrode is normally called the cathode, or emitter, and the other is called the anode, or plate. Ordinarily, electrons in the cathode are prevented from escaping from the surface by a potential-energy barrier. When an electron starts to move away from the surface, it induces a corresponding positive charge in the material, which tends to pull it back into the surface. To escape, the electron must somehow acquire enough energy to overcome this energy barrier. At ordinary temperatures, almost none of the electrons can acquire enough energy to escape. However, when the cathode is very hot, the electron energies are greatly increased by thermal motion. At sufficiently high temperatures, a considerable number of electrons are able to escape. The liberation of electrons from a hot surface is called thermionic emission.

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Electrical Engineering Fresher Jobs

CONSULTANCY (ELECTRICAL ENGINEERING)

1.      APJ Projects http://www.apjprojects.com

2.      Consolidated Consultants and Engineers Pvt. Ltd http://www.cceplt.com

3.      DSON Enterprises http://www.dsonenterprises.com

4.      Eltech Engineers http://www.eltechindia.com/

5.      John Mech-El Technologies (P) Ltd http://www.johnmech-el.com/

6.      Mandvi Electric Works http://www.bicserve.com/

7.      Miraj Instrumentation Services http://www.mirajinstrumentation.com

8.      PG Associates http://www.engineeringconsultant.in

9.     Power Gem Engineers Consultants Power.http://www.powergem.com/

10.   Secon Engineers http://www.seconindia.com

11.   Shanti Enterprises Electricals Limited http://www.shantielectricals.com

12.   Shashi Electricals http://www.shashielectricals.com

13.   SK Systems http://www.sksystem.com

14.  Tata Consulting Engineers http://www.tce.co.in

15.  Nutronics India http://www.nutronicsindia.com/

ELECTRICAL APPLIANCES-

1.      Ajay Industrial Corporation http://www.ajayindustrial.com/

2.      Ankit Electricals http://www.ankitelectricals.com

3.      A.P.C. System & Products Pvt. Ltd http://www.apcsp.com

4.      Arka Trading & Services http://www.mfdplaza.in

5.      Bajaj Electricals Ltd - Part of Bajaj Group. http://www.beltp.com

6.      Electroil http://www.electroil.com/

7.      Eveready Industries India Ltd http://www.evereadyindustries.com/

8.      Graftec india http://graftec.trade-india.com

9.      Indexelectronics http://www.indexelectronics.com

10.  Khaitan Group http://www.khaitan.com/

11.  Lloyd Electric & Engineering Limited http://www.lloydengg.com/

12.  Modern Electrical Stores http://www.modernelectricalsindia.com/

13.  Needo electronics and electricals pvt. Ltd.http://www.needoindia.com

14.  Picasso home products http://www.picassoappliances.com/

15.  Polor Industries Ltd http://www.polarinc.com/

16.  Rajshree India Ltd. http://www.rajshreefans.com

17.  Shilpa Electricals http://www.shilpaelectricals.com/

18.  Super Impex http://www.superimpex.com

19.  Tri Star Engineering Industries http://www.tristarengg.com

20.  Vijay Electricals http://www.vijayelectricalspune.com/

21.  Vxl Technologies Ltd. http://www.vxldesign.com

22.  XtremeWorx http://www.xtremeworx.net

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Power Systems Objective Questions: Part1

POWER SYSTEM OBJECTIVE QUESTIONS FROM COMPETITIVE QUESTIONS(GATE, IES)

(1)- Power is transfered from system A to system B by an HVDC link as shown in the figureA.If the voltages V_AB and V_CD are as indicated in the figureA, and I>0,then

fig.A

   A.. VAB<0,VCD<0,VAB>VCD

   B. VAB>0,VCD>0,VAB>VCD

   C. VAB>0,VCD>0,VAB<VCD

   D. VAB>0,VCD<0

Ans:C

(2)- Consider a step voltage wave of magnitude 1pu travelling along a lossless transmission line that terminates in a reactor.The voltage magnitude across the reactor at the instant the travelling wave reaches the reactor is

fig.B

   A. -1pu

   B.  1pu

   C.  2pu

   D.  3pu

Ans: A

(3)- Consider two buses connected by an impedance of (0+j5)Ω. The bus 1 voltage is 100∠30° V, and bus 2 voltage is 100∠0° V. The real and reactive power supplied by bus 1, respectively are

   A. 1000W,268Var

   B. -1000W,-134Var

   C. 276.9W,-56.7Var

   D. -276.9W,56.7Var

Ans:A

(4)- A three-phase, 33kV oil circuit breaker is rated 1200A, 2000MVA, 3s. The symmetrical breaking current is

   A. 1200A

   B. 3600A

   C. 35kA

   D. 104.8kA

Ans:C

(5)- Consider a stator winding of an alternator with an internal high-resistance ground fault.The currents under the fault condition are as shown in the figure.The winding is protected using a differential current scheme with current transformers of ratio 400/5A as shown. The current through the operating coil is

 A. 0.17875A

 B. 0.2A

 C. 0.375A

 D. 60kA

Ans: C

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CHARGING OF PLUGIN ELECTRICAL VEHICLE

Task 4: Advanced managing strategies for multiple charging requests in an electrical grid (The “smart” approach).

In task 4, we analysed the effectiveness of smart strategies in which the charging processes of each user are scheduled on the basis of a more sophisticated priority criterion rather than simply considering only the arrival time, and the charging rate of each user is adapted to the grid load condition during the charging process.

We firstly considered the following priority and charging rate assignment functions:

The priority function (1) is formulated to assign priority to the users on the basis of both the amount of power required and the electricity rate they are disposed to pay. The influence of each of these aspects (power required and electricity rate) on determining the user priority can be adjusted by tuning the weighting coefficients a and b, with a+b=1.

The charging rate assignment function (2) consists in distributing the energy required by each user over the entire time period available before the user leaves the system.

Since the energy still required and the time available for each user change during the process, the implementation of the smart strategy requires a “frequent” communication about the user state of charge, and the updating of the priority and charging rate at regular intervals. The duration of these intervals is indicated as time resolution. In this task, we used a time resolution of 0.25 h. 

Task 5: try the effectiveness of your own advanced managing strategy.

In this task we carried out several simulations by introducing different smart strategies. In particular, we experimented different ways of assigning the priority of the users and different time resolution values. 

Task 6: Large scale scenario.

In this final task we evaluated the effectiveness of the different strategies previously analyzed in a large-scale scenario in which several grid nodes are considered. We considered different Uniform and Gaussian profiles for the electricity rate and the arrival and departure times of the users. 

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CHARGING OF PLUGIN ELECTRICAL VEHICLE USING MATLAB

Stage  1: PEV charging in a conventional distribution grid

Task 1: Understanding basic battery charging parameters.

In Task 1, we dealt with the charging process of a single PEV to familiarize with the basic concepts about battery charging. We selected different values of the available power from the grid, the battery charging rate and capacity, the initial state of charge and the user arrival and departure times in order to evaluate when the user is actually satisfied in terms of state of charge at the departure time.

 

Task 2: A real case of study: multiple charging requests in a conventional electrical grid (The “superdumb” approach).

In Task 2 we simulated the evolution of a local node of the distribution grid in which six PEVs have to be charged by using the so-called “superdumb” approach. In this case, the electrical grid is a conventional one, without any additional feature to support specific procedures or strategies to manage the vehicles charging. No communication is then possible between the PEVs and the utility in order to adapt the charging process to the grid load conditions. This means that the charging process of a PEV starts when the vehicle is plugged in and it is performed at the maximum charging rate allowed by the battery (provided that enough power is available from the grid at the time of plug-in). In the case when the power request exceeds the available power at that time, the charging request is rejected and the user cannot charge his battery. We performed several analyses by considering different realistic user profiles in terms of battery capacity, charging rate, arrival and departure times.

Task 3: Simple managing strategies for multiple charging requests in an electrical grid (The “dumb” approach).

In Task 3 we used the “dumb” approach, which is still a First-Come-First-Served strategy in which the charging process of a PEV is performed at the maximum charging rate, provided that the grid is capable of supplying the required power. However, in the “dumb” scenario, users can communicate to the grid manager their arrival and their (expected) departure times, the required energy to complete the charge as well as the instant at which they are actually fully charged. Thanks to this information exchange, a kind of negotiated charging can be implemented: if a user cannot be served at the time of arrival, its charging request is not completely rejected, but just queued until sufficient power becomes available (obviously, if power is available before the user departure time).

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Electrical Final year Project 2014

CHARGING OF PLUGIN ELECTRICAL VEHICLE--

Plug-in electric vehicles (PEVs) may guarantee significant advantages with respect to traditional gasoline-fueled vehicles in terms of:

• greenhouse gas emissions reduction;

• energy consumption reduction;

• air quality improvement;

• oil consumption reduction;

• higher drive comfort.

Owing to all these potentially significant societal benefits guaranteed by transport electrification, PEVs are expected to diffuse rapidly over the next few years.

Unfortunately, the resulting energy request for vehicle batteries recharging may create overload conditions for the electrical grid. It is then necessary to develop ad hoc strategies to manage the charging of these vehicles and consequently to adapt the grid infrastructure.

The project encourages you to cope with the very hot real-world problem arising from the increasing demand for charging Plug-in Electric Vehicles through the electrical energy distribution grid. You will analyze the effect of multiple quasi-contemporary charging requests on the grid, hence discovering how, as the number of users to be charged increases, either the grid collapses or the user requests may not be entirely fulfilled. You will be asked to analyze the effectiveness of smart energy dispatching strategies and smart battery charging methods in mitigating (or completely overcoming) the grid overload problems. You will also experience some of the real-world engineering trade-offs commonly encountered in developing scheduling strategies for the management of a shared resource such as the energy available from the grid.

A study by  the Pacific Northwest National Laboratory showed that the use of PEVs with the existing power plants in the U.S. could result in a 30% improvement in energy consumption per Vehicle Miles Traveled (VMT), a 27% reduction in CO₂ emissions, and a 52% reduction in imported oil [1]-[3].

Moreover, PEVs offer the unique possibility of being supplied by using clean renewable energy sources. According to a study of the Berkeley Center for Entrepreneurship & Technology of the University of California, the total emissions of the U.S. vehicle fleet would even be reduced by 62% by 2030 if about half of the fleet were powered by clean electricity. Owing to all these potentially significant societal benefits guaranteed by transport electrification, PEVs are expected to diffuse rapidly over the next few years. Indeed, electric vehicles are predicted to account for 64-86% U.S. sales of new light vehicles by 2030 [4].

Typically, PEVs require 0.2-0.3 kWh for a mile of driving and are characterized by battery capacity values in the range of 8-55 kWh. As a consequence, the additional demand for electric power required to charge a large fleet of PEVs in reasonable time may add a significant load to the distribution grid. For example, a study of the Joint Research Centre of the European Commission carried out for a real case study has recently shown that the maximum electric power request would increase by about 30% if PEVs should reach 25% of the vehicle fleet [5].

In a similar scenario, the presence of several contemporary charging requests could cause overload conditions in local nodes of the grid if the charging processes of the PEVs are not properly managed and scheduled. These overloads might lead to interruptions and/or unbalanced conditions which may degrade the quality of service, increase line losses and damage utility and customer equipment [3], [5].

It is therefore mandatory to develop innovative strategies for the scheduling of the battery charging process to avoid dangerous grid load conditions. Unfortunately, both electrical distribution grids and charging systems available nowadays are essentially “dumb” structures that offer no (or very poor) interacting capabilities. Thus, at the present time, the only possible working modality is to start the charging process of a PEV just when the vehicle is plugged in (or, at most, with a delay fixed by the user) without any dynamic adaptation mechanism of the charging conditions to the actual grid load. Clearly, the actual implementation of innovative strategies to overcome the problems discussed will require the combined development of smart grid infrastructures and advanced charging systems capable of reciprocal interaction. Only pursuing this multifaceted “smart revolution”, in which the engineers’ contribution is fundamental, it will be possible to support PEVs diffusion and to benefit from the potential huge advantages deriving from their extensive penetration worldwide.

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