We hereby declare that this project was carried out by us under the supervision of Md. First of all, we express our heartfelt thanks and gratitude to Almighty Allah for His divine blessing enabling us to successfully complete this project.
Introduction 8
Literature Review 8
Organization of the Project 8
One of the important features of a transformer is the electrical isolation between the primary and secondary. The voltages in the primary and secondary windings are directly proportional to the turns ratio of the two windings. The combined effect of the leakage current and the electric field around the windings is what transfers energy from the primary to the secondary.
The term step recovery relates to the shape of the reverse recovery characteristic of these devices. It is the ratio of the electric charge on each conductor to the potential difference between them. The more a capacitor is charged, the greater its voltage drop; that is, the more it "pushes back" against the charging current.
The double of the capacitor is the inductor, which stores energy in a magnetic field rather than an electric field. 34;Axial" means that the leads are on a common axis, typically the axis of the cylindrical body of the capacitor - the leads extend from opposite ends. In a full-wave rectifier circuit, two diodes are now used, one for each half of the cycle.
The single secondary winding is connected to one side of the diode bridge network and the load to the other side, as shown below.
List of component 10
Working principle 11
In this circuit we use six capacitors, c1 to c5 are used to get constant input to the regulator and it also helps to reduce the sharp peaks in the output. Connect the 2700 µF capacitor near the input of the regulator and the 100 pF capacitor to the output, because this capacitor reduces the noise and also helps to reduce the ripples produced by the regulator so that regulated output has less ripples.
Voltage Regulator and Transformer 13-19
History 28
October 1745 Ewald Georg von Kleist of Pomeranian in Germany discovered that charge could be stored by connecting a high-voltage electrostatic generator with a wire to a volume of water in a hand-held glass jar. Von Kleist's hand and water acted as a conductor and the jar as a dielectric (although the details of the mechanism were misidentified at the time). Von Kleist found that touching the wire resulted in a powerful spark, much more painful than that obtained from an electrostatic machine.
Daniel Galatz was the first to combine multiple pots in parallel into a "battery" to increase charge storage capacity. He also adopted the term "battery" (denoting increasing power with a row of similar units as in a battery of guns), and then applied it to clusters of electrochemical cells. Leyden jars or more powerful devices using flat glass plates alternating with foil conductors were used exclusively until about 1900, when the invention of wireless (radio) created a demand for standard capacitors, and the steady move toward higher frequencies required capacitors of lower inductance.
Theory of operation 28
The following year, the Dutch physicist Pieter van Musschenbroek invented a similar capacitor, called the Leyden jar, to the University of Leiden where he worked. He was also impressed by the force of the shock he received, and wrote: "I will not take a second shock for the kingdom of France." Benjamin Franklin examined the Leyden jar and concluded that the charge was stored on the glass, not in the water as others assumed.
Leyden jars were later made by coating the inside and outside of the jars with metal foil, leaving a gap at the mouth to prevent arcing between the foils. The term was first used for this purpose by Alessandro Volta in 1782, in reference to the device's ability to store a higher density of electric charge than a normal insulated conductor. Because the conductors (or plates) are close together, the opposite charges on the conductors are attracted by their electric fields, allowing the capacitor to store more charge for a given voltage than if the conductors were separated, giving the capacitor a large capacitance.
Hydraulic analogy 29
The current changes the charge on the capacitor, just as the water flow changes the position of the membrane. This is just like when a water current moves a rubber membrane, it increases the amount of water on one side of the membrane and decreases the amount of water on the other side. This is similar to the fact that the more the membrane is stretched, the more it pushes back on the water.
Charge can flow "through" a capacitor even though no individual electron can pass from one side to the other. This is analogous to the fact that water can flow through the pipe even though no water molecules can pass through the rubber membrane. Of course, the flow cannot continue in the same direction forever; the capacitor will suffer dielectric breakdown, and analogously the membrane will eventually break down.
Energy of electric field 30
More specifically, the effect of an electric current is to increase the charge on one plate of the capacitor and decrease the charge on the other plate by an equal amount. Capacitance describes how much charge can be stored on one plate of a capacitor for a given "thrust" (voltage drop).
Current-voltage relation 31
- DC circuits 31
- AC circuits 32
At t = 0, the voltage across the capacitor is zero and the voltage across the resistor is V0. When the capacitor reaches equilibrium with the source voltage, the voltages across the resistor and the current through the entire circuit decay exponentially. The case of discharging a charged capacitor also shows exponential decay, but with the initial capacitor voltage replacing V0 and the final voltage being zero.
Impedance, the vector sum of reactance and resistance, describes the phase difference and amplitude ratio between a sinusoidally varying voltage and a sinusoidally varying current at a given frequency. The -j phase indicates that the AC voltage V = ZI lags the AC current by 90°: the positive current phase corresponds to the voltage increase as the capacitor charges; zero current corresponds to constant instantaneous voltage, etc. Capacitors differ from resistors and inductors in that the impedance is inversely proportional to the defining characteristic; i.e., capacity.
Capacitor types 33
Dielectric materials 34
Ceramic capacitors are generally small, inexpensive, and useful for high-frequency applications, although their capacitance varies greatly with voltage and they age poorly. Glass and mica capacitors are extremely reliable, stable, and tolerant of high temperatures and voltages, but are too expensive for most common applications. Electrolytic capacitors and supercapacitors are used to store small and large amounts of energy, respectively, ceramic capacitors are often used in resonators, and parasitic capacitance occurs in circuits where the simple conductor-insulator-conductor structure is formed unintentionally by the circuit's configuration layout.
Electrolytic capacitors offer very high capacitance, but suffer from poor tolerances, high instability, gradual loss of capacitance, especially when exposed to heat, and high leakage current. Electrolytic capacitors self-degrade if not used for a period (about a year) and when full current is applied they can short circuit, permanently damaging the capacitor and usually blowing a fuse or causing failure of rectifier diodes (for example in older equipment, arcing in rectifier tubes). AC capacitors are specially designed to operate on mains voltage AC circuits.
Structure 36
They are commonly used in electric motor circuits and are often designed to handle large currents, so they tend to be physically large. They are usually robustly packaged, often in metal containers that can be easily earthed/earthed. Radial conductors may more accurately be referred to as tandem; they rarely actually line up with radii of the body's circle, so the term is imprecise, though universal.
The wires (until bent) are usually in planes parallel to those of the flat body of the capacitor, and extend in the same direction; they are often manufactured in parallel. Surface-mount components avoid unwanted high-frequency effects due to the cables and simplify automated assembly, although manual operation is made difficult due to their small size. Mechanically controlled variable capacitors allow plate spacing to be adjusted, for example by rotating or sliding a series of movable plates into alignment with a series of stationary plates.
Capacitor markings 37
Rectifier 38-43
- The Full Wave Rectifier 38
- Full Wave Rectifier Circuit 39
- The Full Wave Bridge Rectifier 40
- The Diode Bridge Rectifier 40
- The Positive Half-Cycle 40
- Cost comparison 45
Since the output voltage across the resistor R is the phase sum of the two waveforms combined, this type of full-wave rectifier circuit is also known as a "bi-phase" circuit. The peak voltage of the output waveform is the same as before for the half-wave rectifier, provided that each half of the transformer windings has the same rms voltage. Another type of circuit that produces the same output waveform as the full-wave rectifier circuit above is the full-wave bridge rectifier.
However, the full-wave bridge rectifier gives us a larger average DC value (0.637 Vmax) with less superimposed ripple while the output waveform is twice that of the frequency of the input supply frequency. The smoothing capacitor converts the full-wave ripple output of the rectifier into a smooth DC output voltage. Therefore, the fundamental frequency of the ripple voltage is twice that of the AC supply frequency (100Hz) where for the half-wave rectifier it is exactly equal to the supply frequency (50Hz).
Result 46-47
Mahmudur Rahman Senior Lecturer Department of EEE Daffodil International University for his valuable suggestions and guidance throughout this project work. He always helps our working day in electronic lab and find our project error. Fayzur Rahman, Head, Department of EEE Electrical and Electronic Engineering, Daffodil International University for his valuable suggestions.
Successful completion of the project report a special mention goes to those who directly or indirectly helped for work.
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