1.2.6 HARMONIC DISTORTION
Harmonics are sinusoidal component of periodic wave having an frequency that is an integral multiple of fundamental frequency.
Now a day more use of power electronic switches and devices cause harmonics. Examples of harmonics producing loads are computers, adjustable speed drives, etc.
Mitigation of harmonics can be done with the help of passive filters or active filters. Hybrid of active and passive filters also solves problems of harmonics.
Figure 1.5 Distorted Current Waveform Due To Harmonics
1.3 SOURCES OF POWER QUALITY PROBLEMS
Sources of PQ problems in all the fields such as domestic, commercial are industrial are closely related with power electronics. For example residential equipments such as PC’s and TV, office equipments like printers and industrial equipment such as PLCs.
Nonlinear loads are the most common causes of harmonics and neutral currents. Various electrical equipments such as transformers, motors and cables are affected by harmonics. Equipments such as PC’s and printers using switched mode power supply produce neutral currents.
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The second method of measuring three phase power is the useful for both balanced and unbalanced loads. By connecting a wattmeter with its current probes in series with red phase and volt probes between red and yellow phase. The second wattmeter should be connected with its current probes in series with the blue phase and the volt probes between the blue and yellow phases. By adding these two values together there total power for the system can be
This chapter provides some insight into pulse wave analysis and its relation to arterial diseases. The shape of the arterial pulse wave is an augmentation of the forward traveling wave with the reflected wave. The amount of wave reflection is dependent on the arterial wall properties such as arterial stiffness and is expressed in terms of Augmentation Index. This approach has been studied extensively using various measuring techniques, all of which have respective advantages and disadvantages. The purpose of PWA can be seen in the section describing the medical conditions that affect the wave shape. The discussion is included to assist the reader in understanding the purpose of pulse wave analysis.
This condition can be treated various ways depending on “the type and frequency of arrhythmias, associated symptoms…, and the presence of structural heart disease” (Cleveland Clinic, 2014). Some patients may not need treatment at all, since they show not symptoms, since sometimes this condition can be naturally eliminated over the first year of life, but may still be required to have regular schedule appointments with the physician so the patients can be monitored. If symptoms are prevalent, the different treatment methods include a pacemaker, defibrillator, surgery, and medicine.
The module AC/DC is directly related to the career path of the electrical linemen. In the module i learned about two types of electrical current, alternating (AC), and direct current (DC). In direct current (DC), the electric charge (current) only flows in one direction. Electric charge in alternating current (AC), on the other hand, changes direction periodically. The voltage in (AC) circuits also periodically reverses because the current changes direction. Electrical lineman work on power lines and other thing that have (AC) or (DC) current depending on what they are working on. Lineman work on electrically energized (live) and de-energized (dead) power line. They may perform a number of tasks associated with power lines, including installation or replacement of distribution equipment such as capacitor banks, distribution transformers on poles, insulators and fuses.
· B-phase transformer (EMTU-TT01) · Feedback electronic wattmeter · Multi-range moving-iron ammeter · Instrument voltage transformer THEORY AND INTRODUCTION ----------------------- Transformers are used all over the world to step-up and step-down electricity. The transformer is one of the most commonly used electrical devices. The reason the transformer is so popular is because they range in size from 240V to well over 240kV, stepping -up and stepping-down electricity all over the world.
Electricity and electrical components are a major part of our lives today. Our lives pretty much come to a halt if there is a power outage or if our electrical devices stop working, sometimes we even start panicking because we are so dependent on these components that we cannot afford to lose them and their importance and use only increases as time passes. We all use these electrical devices and also electricity itself but most of us do not think about the math and physics that works behind all of these things.
ways. The use of electricity will reduces the usage of the earth’s resources such as gas and oil.
- - - . "Western Electric #202 Desk Phone." n.pag. Online: Available: http://www.cyber-comm.net/~chuck/we202.html, Mar. 31, 1999.
Alternating current is always changing in direction and amplitude. The current flow in alternating current changes in even intervals. Ac usually changes in power and direction. The vast majority of power supplied for households and big business is alternating current. This is because of the ease of generating alternating current in alternators. The main concept of alternators is moving a conductor through magnetic lines. The change in the magnetic field around the conductor or vice versa makes electrons move. When you have physically moved either the conductor or magnet in a complete 306-degree circle you have produced one sine wave or one complete cycle. The amount of time it takes to complete one cycle is referred to as a period. The frequency of an alternating sine wave is the amount of cycles per second. Frequency is measured in hertz. One hertz is equivalent to one cycle per second. The frequency coming out of your electrical plug at home is 60 Hz. The peak value in a sine wave is the top voltage level away from zero. The peak-to-peak voltage value is referring to difference between the positive peaks value to the negative peak value. The effective or rms value of a sine wave is the actual amount you would use or measure using a multi-meter. In three-phase alternating current there are three different coils or conductors that produce three different sine waves.
There are a few parts of sounds waves that we should be familiar with to better be able to understand the physics of music. The crest is the highest point of a wave, while the trough is the lowest. The wavelength of a wave is the distance between two adjacent ...
waves are further divided into two groups or bands such as very low frequency (
The Fourier series of all kinds of signals and waveforms cannot be calculated. The function must satisfy some specific conditions known as the Dirichlet condition for convergence of Fourier series. These conditions are then used to define and prove the Fourier Convergence Theorem which gives the sum of the Fourier series. These conditions are that a periodic signal must be a piecewise continuous function, have finite number of extrema (maxima and/or minima) and have finite number of discontinuities (points in the function’s domain where the function is not continuous i.e. has a break).
Electrical engineering deals with electricity, electro-magnetism and electronics. It also covers power, control systems, telecommunications and signal processing. These engineers are usually concerned with large-scale electrical systems such as motor control and power transmission, as well as utilizing electricity to transmit energy. Electrical engineers may work on a diverse range of technologies, from the design of household appliances, lighting
The Physics Classroom. "Frequency and Period of a Wave." Physic Classroom. The Physics Classroom, 1996. Web. 28 Nov. 2013. .