Relays, Working principle of relay,

            Introduction:

An electrical relay is a switch which is under the control of another circuit. A classic example of an electrical relay is the system used to start a car. When someone turns an ignition key, the ignition does not interact directly with the car battery.

Grid Substation, Introduction, Grid station and National Grid substations

Grid Substation                                                            

  Introduction:

A grid substation is part of the electricity grid system -i.e. part of the transmission system. In the Bangladesh, this involves voltage levels of 400 kV, 230 kV, 132KV,66,11KV,  KV,440V,220V132 kV.Transmission of power occurs through the power distribution grid.

Recommendation for Future Work ,Results Validated By Theoretical Modeling and Development of Algorithm

Recommendation for Future Work:

          In the whole research work, attention was paid to simulate all the structures by commercial EM software Zeland IE3D. Investigations need to be justified experimentally by VNA and compared with simulated results.

Motivation, Reasoning and the Proposed Proposition of EBG structures and Application of Dumbbell shaped EBGS as BPF

Motivation, Reasoning and the Proposed Proposition of EBG structures

From the intensive literature survey it is clear that the inclusion of EBGSs / dumbbell shaped EBGSs improve the performance of microwave components and devices significantly. From the performance of novel 2-D EBG structures for microstrip lines it is obvious that the performance is hindered by the optimized value of FF.

Realization of Band Pass Filter (BPF) and Non-uniform EBGS

 Realization of Band Pass Filter (BPF)

Each type of filters has different type of applications in the field of microwave communication system. There is a well defined formula deduced from the Bragg’s condition for circular shaped EBGS.

Performance of uniform circular PBGS Assisted BPF, Performance of reference BPF, Performance of BPF on 2-D array of uniform circular PBGSs, Performance of BPF on dense 2-D array of uniform circular PBGSs, Performance of BPF with three line uniform circular PBGSs, Performance of BPF with uniform circular PBGSs under two extreme 50 ohm lines, Performance of BPF with uniform circular PBGSs under all the lines Performance of BPF with uniform circular PBGSs under all the line

    Performance of uniform circular PBGS Assisted BPF

Theoretical results are produced for different geometries of uniform circular PBGS assisted BPF. To see the effect of uniform circular PBGS in harmonic suppression the performance of reference BPF is shown. Finally the insertion loss performances of a standard BPF and uniform circular PBGS assisted BPF are shown to compare the results.

Simple T-line and its performance, S-Parameter Performance of a microstrip T-line, Design of uniform circular PBGSs for Harmonic Suppression, Standard BPF, BPF on 2-D array of uniform circular PBGSs, BPF with dense 2-D uniform circular PBGSs, BPF with PBGSs under 50-ohm and central coupled lines

    Simple T-line and its performance:

T-line is just a line with a defined length and width on the upper surface of the substrate which is created by removing copper coating from the surface except the desired region. The figure is shown below where the blue region is a typical T-line whose length is 100 mm and width is 2.2642 mm (calculated by PCAAD for 50Ω microstrip T-line where dielectric constant of the substrate is 2.45 and thickness is 31 mils).

Corrugated Surface and Metal Pad or High-Impedance Surface

Corrugated Surface

A corrugated surface is a metal slab into which a series of vertical slots are cut. The slots are narrow so that many of them fit within one wavelength across the slab. Each slot can be regarded as a parallel plate transmission line, running down into the slab, and shorted at the bottom.

Microwave Filter design, Applications to BPF ,Application to LPF, Application to dual stopband filter, Band-pass filters

Microwave Filter design

              There is a vast amount of published literature on the design of microwave filters from which some are highly mathematical. Fortunately there are some relatively straight forward procedures which enable us to design certain useful classes of microwave filters. Filter designing using the image parameter method consist of a cascade of simpler two-port filter sections to provide the desired cutoff frequencies and attenuation characteristics but do not allow the specification of a frequency response over the complete operating range.

Microwave Filters,Lumped - element LC filters , Planar filters, Coaxial filters, Cavity filters, Dielectric filters and Electro acoustic filters

Lumped - element LC filters

An LC tank circuit consisting of parallel or series inductors and capacitors is a best example of a simplest resonator structure. These LC tank circuits have the advantage of being very compact & small in size, but having the low quality factor of the resonators which leads to relatively poor performance. 

Figure: Commercial photograph of Lumped-element LC filters.

Introduction, Microwave filters, Filter and There are mainly four types of filters with respect to functions

  Microwave filters

   Introduction

          A filter is a two-port network used to control the frequency response at a certain pointin an RF or microwave system by providing transmission at frequencies within the passbandof the filter and attenuation in the stopband of the filter.

Microwave filters represent a class of electronic filter design to operate on signals in the MHz to GHz frequency ranges. This frequency range is the range used by most broadcast radio, television, wireless communications like Cell phone, Wi-Fi, Wi-Max and the most radio frequency and microwave devices will include some kinds of filtering on the signals transmitted or received.

Theoretical Background and Microwave Transmission lines Theories

 Introduction:

Recently EBGSs have occupied significant portions of microwave engineering literature to enhance the performance of many microwave devices and components. The nomenclature EBG is actually used in the optical communication. Recently they are scaled down to RF engineering. They are very old concepts in terms of periodic structures. EBG structures are periodic in nature.

Application of microwave engineering, Microwave Transmission lines and Microwave filters

            In microwave engineering high frequency and short wavelength make unique opportunities for the microwave systems. This is because of following consideration:

§  Antenna gain is proportion to the electrical size of the antenna. At higher frequencies, more antenna gain is therefore possible for a given physical antenna size, which has important consequences for implementing miniaturized microwave system.

Introduction of Frequency range of waves and Frequency Band Designation

  Introduction:

The microwave refers to an alternating current signals with frequencies between 300 MHz and 300 GHz with corresponding electrical wavelength between λ = c/f = 1m and λ = 1mm respectively. It is quite impossible to solve microwave network problem using standard circuit theory directly but standard circuit theory is an approximation of the broader theory of electromagnetism as described by Maxwell’s equations.

Gas Turbine Power Plant Modelling for Operation Training

           The $11.4 billion worth of non-aviation gas turbines produced in 2008, $9.6 billion—more than 80 percent—were for electrical generation (Langston, 2008). Particularly, in Mexico, about 15% of the installed electrical energy (no counting the electricity generated for internal consuming by big enterprises) is based on gas turbine plants (CFE web page), either working alone or in combined cycle power plants (and 8% produced directly by gas turbines) that offers an important roll in improving power plant efficiency with its corresponding gains in environmental performance (Rice, 2004).

The Biased p-n Junction

     An externally applied potential will alter the potential difference between the p- and n-regions. This in turn will modify the flow of majority carriers, so that the junction can be used as a “gate”. If the junction is forward biased by applying a positive voltage V to the p-region Fig. , its potential is increased with respect to the n-region, so that an electric field is produced in a direction opposite to that of the built-in field.

THE IGFET/MOSFET

The second (and most important) family of FETs are those known under the general title of IGFET or MOSFET. In these FETs, the gate terminal is insulated from the semiconductor body by a very thin layer of silicon dioxide, hence the title ‘Insulated Gate Field Effect Transistor,’ or IGFET. Also, the devices generally use a ‘Metal-Oxide Silicon’ semiconductor material in their construction, hence the alternative title of MOSFET.

ALTERNATOR UNIT REPAIR AND ALTERNATOR

Disconnect grounded cable at battery before removing or attaching battery cable at alternator output terminal. Otherwise, a tool shorted to the battery cable at the output terminal can quickly heat enough to cause a skin burn or damage the tool or cable.

Multiple Impulse Method (SIM/MIM)

       The Multiple Impulse Method is the most advanced cable fault prelocation method available.

Every cable fault that is either a high resistive or intermittent fault can not be indicated by means of the TDR method. The low voltage impulse sent out by the Time Domain Reflectometer is not reflected at the faulty position, as the fault impedance compared to the insulation impedance of the healthy part of the cable is not significantly lower.

       

Electrochemical capacitor performance

The performance characteristics of electrochemical capacitors differ somewhat from those of onventional capacitors. In Fig. 4 the impedance plane representation (Nyquist plot) of an ideal capacitor and a simplified electrochemical capacitor, both having the same ESR (equivalent series resistance at 1 kHz), are compared.

Polymers ,Electrolyte and Organic

 Polymers

Polymeric materials, such as p- and n-dopable poly(3-arylthiopene), p-doped poly(pyrrole), poly(3-methylthiophene), or poly(1,5-diaminoanthraquinone) have been suggested by several authors [17–19] aselectrodes for electrochemical capacitors.

Classification of electrochemical capacitors

                    Electrochemical capacitors may be distinguished by several criteria such as the electrode material utilized, the electrolyte, or the cell design.With respect to electrode materials there are three main categories: carbon based, metal oxides and polymeric materials.

Principle of energy storage

Electrochemical capacitors store the electric energy in an electrochemical double layer (Helmholtz Layer) formed at a solid:electrolyte interface.

Positive and negative ionic charges within the electrolyte accumulate at the surface of the solid electrode and compensate for the electronic charge at the electrode surface.

PBG Assisted Reconfigurable Phased Array Antennas

EBG assisted reconfigurable phased array antenna is investigated applicable for dual-band operations. With a view to achieving dual-band operation another set of 4 antennas is connected with shorter resonant length (lg/4 that is 1/4^th wavelength).

Superposition Theorem

The superposition theorem is unquestionably one of the most powerful in this field. It has such widespread application that people often apply it without recognizing that their maneuvers are valid only because of this theorem.

Energy Stored By a Capacitor , Stray Capacitances , Flash Lamp

An ideal capacitor does not dissipate any of the energy supplied to it. It stores the energy in the form of an electric field between the conducting surface. A plot of the voltage , current and power to a capacitor during the charging phase is shown.

Transients in Capacitive Networks the Discharging

We know investigation how to discharge a capacitor while exerting some control on how the discharge time will be. You can of course place a lead directly across a capacitor to discharge it very quickly and possibly cause a visible spark.

Periodic Bandgap Structures

PBG structures are periodic in nature, which may be realized by drilling, cutting and etching on the metal or substrates. They may be formed in the ground plane or over the substrate. 

 

Periodic structures

Due to the realization of growing demand for larger bandwidth, high capacity RF and microwave devices as well as better efficiency in the field of wireless technologies new technologies of designing such devices are being reported all over the world. 

 Figure 3.16: 1D circular pattered EBGS etched beneath the T-line designed by Zeland ie3d software.

On the consequence of such latest technologies realizing microwave filters and antennas with Planar Electromagnetic Bandgap Structures are one of the best of them.

Type of Capacitor and Leakage Current

Types of Capacitors

Capacitors like resistors can be listed under two general headings fixed and variable. The symbol for the fixed capacitor appears in , Note that the curve side is normally connected to ground or to the point of lower dc potential. The symbol for variable capacitors appears.

Three Phase Generator

The three phase generator in has three induction coils placed 120 degree apart on the station , as shown symbolically. Since the three coils have an equal number of turns, and each coil rotates with the same angular velocity the voltage induced across each coil has the same peak a value shape and frequency.

Current

The question 'Which came first the chicken or the egg?' can be applied here also because the layperson has a tendency to use the terms current and voltage interchangeably as if both were source of energy it is time to set things straight,

Voltage

If we separate the 29th electron from the rest of the atomic structure of copper by dashed line as shown we create regions that have a net positive charge as shown in and for the region inside the dashed boundary , the number of points in the nucleus exceeds the number of orbiting electrons by i so the net charge is positive as shown in both figures.

Solid State Era

In 1947 physicists William Shockley, John Bardeen and Walter H. Brattain of Bell Telephone Laboratories demonstrated the point contract transistor an amplifier constructed entirely of solid state materials with no requirement for a vacuum glass envelope or heater voltage for the filament.

Sinusoidal Ac Voltage Characteristic and Definitions

Sinusoidal ac voltage are available from a variety of sources. The most common source is the typical home outlet, which provides an ac voltage that originates at a power plant. Most power plants are fueled by water power ,oil, gas or nuclear fusion.

Nodal Analysis

A close examination of appearing reveals that the subscript voltage at the node in which kirchhoff's current law is applied is multiplied by the sum of the conductance attached to that node. Note also that the other nodal voltages within the same equation are multiplied by the negative of the conductance between the two nodes.

Constant Current Alarm System

The basic component of an alarm system using a constant current supply are provided . This design is improved over that provided in this lesson in the sense that it is less sensitive to charges in resistance in the circuit due to heating humidity charges in the length of the line to the sensor and so on.

Conductors & Insulatoes

Different wires and place across the same two battery terminals allow different amount of charge to flow between the terminals. Many factors such as the density, mobility and stability characteristics of a material account for these variation in charge flow.

Distribution network configurations

Distribution networks are typically of two types, radial and interconnected (see spot network). A radial network leaves the station and passes through the network area with no normal connection to any other supply. This is typical of long rural lines with isolated load areas.

Designing equation

In the PBG engineering it is a conventional rule to use Bragg’s condition [13] to calculate the central stopband frequency provided by PBGSs.

Literature Survey on PBG Assisted Microwave Devices

A comprehensive literature survey on recent development of PBG structures and their applications to microwave devices including antennas has been reported in this chapter. PBG structures are found to play vital roles in enhancing the performance of the microwave components and devices.

Plannar Photonic Bandgap Structures

Planar PBGSs are a classes of periodic, which are photogenic analogs of the semiconductors. Electromagnetic (EM) waves behave in photonic substrates as electrons behave in semiconductors. Due to these characteristic PBGSs are known as EM bandgap structures (EBGSs). PBGSs exhibit wide band-pass and band-rejection properties at microwave and millimeter-wave frequencies and have offered tremendous applications in active and passive devices [1]-[12].