INTRODUCTION The issue of power quality has become very critical because of the loads which are sensitive to power quality disturbances. Sometimes, the loads themselves become the major reason for the deterioration in power quality. Electronic devices like computers, process controls and communication equipments are sensitive to the disturbances in the power system. The effect of power quality disturbance on equipment can be considered in terms of susceptibility and vulnerability. The temporary malfunction of a device due to disturbances in the system refers to susceptibility. This phenomenon can be observed in computing devices where if transients exceed a threshold, error occurs. An equipment is said to be vulnerable if the electric transient exceeds its insulation withstand level. This phenomenon can be observed in a rectifier which fails if it is subjected to transient voltages exceeding a certain level. Institute of Electrical and Electronic Engineers (IEEE) Standard IEEE1100 defines power quality as “the concept of powering and grounding sensitive electronic equipment in a manner that is suitable to the operation of that equipment” [2]. 2.2 PERSPECTIVES OF POWER QUALITY [26] The perspectives of power quality are as follows: • This perspective concerns with the customer’s side of the meter. In this, focus is put on the power disturbances that effect the equipments adversely. • This perspective also concerns with the customer’s side of the meter. In this, manufacturer of the equipment should be aware of the level of the power disturbances and their frequencies of occurrences so as to determine the tolerance limit of the equipment. • This perspective is from the utility. They are interested in power ... ... middle of paper ... ...onditions. 2.5.1.1 Voltage sag It is also known as a voltage dip. This is the one of the most common power quality problem. It is defined as a decrease of normal voltage level between 10-90 percent of the nominal rms voltage at the power frequency. It lasts for a duration between 0.5 cycles to 1 minute. The magnitude of voltage sag depends on various factors like the type of fault, the location of the fault and the fault impedance. The time period for which voltage sag occurs basically depends on how fast the fault is cleared by the protective device. Starting of large induction motors, connection of heavy loads and faults in consumer’s installations may lead to voltage sag. It may lead to malfunctioning of information technology equipments, loss of efficiency in electric rotating machines and tripping of contactors and electromechanical relays.
The film Matewan brings to life the workings of a small West Virginia coal-mining town in the 1920's. Stone Mountain, as the town was called, existed for mining exclusively. Every resident of the town worked for the Stone Mountain Coal Company. The company was the dominant force in the community, acting as a feudal lord. It owned all the land, residential areas and restaurants. In this particular town residents had no other choice than to work for the Coal Company because it had monopoly control over all the resources thus creating a feudal economic system. The miners were forced into a bondage contract with the company, because of the lack of choice they had regarding their employment, which is a fundamental element in a feudal system. The owners of the Stone Mountain Coal Company who profit from the coal generated never actually stepped foot on the Stone Mountain mine land. They had no idea who worked for them and what their situations were. The workers never knew their employer instead the owners sent two representatives to ensure the excavation of the coal happened. The representatives became a third force necessary for the existence of feudal economy in Matewan. They were sent from the company to manage the organization and production of the mine. The representativesÕ primary job was to enforce the rules that the company had established in order to maintain power of the town, mine and essentially the workers. They used threats to induce fear in the miners as a way to stimulate and motivate them to work, because the miners had little significant reason to work besides basic survival.
Muller, S., Prowse, D. L., & Soper, M. E. (2012, September 25). CompTIA A+ Cert Guide: Power Supplies and System Cooling | Foundation Topics | Pearson IT Certification. Retrieved March 20, 2014, from http://www.pearsonitcertification.com/articles/article.aspx?p=1945640
The first method of insuring a correct reading is obtained is through using one wattmeter on a balanced load. Using this on an unbalanced load will lead to an inaccurate reading for power. To complete this method a reading with a wattmeter connected from a single line to neutral via the voltage probes and in line with the line on the current probes. By multiplying the value of the wattmeter by three the total system power is found.
Power. It is defined as the capacity or ability to direct or influence the behavior of others or the course of events. Throughout time, certain individuals have acquired power in their society as a way to govern and keep order among their community. Power is not a new concept; it was used in the past by many emperors, kings, and queens, and is still being used by presidents, prime ministers, and dictators. Although, it has been used to further progress societies into what the world is like today, not all power has been used for the best of mankind. But what goes awry to make power turn corrupt? In William Shakespeare's Hamlet, it is illustrated how power can turn corrupt, when authoritative figures, who possess power, abuse it for their personal gain, rather than for the common good of the society.
Greater shift towards smart grids, smart metering and building automation: Smart grids helps in intelligent distribution resulting in minimal losses whereas measurement and reporting of consumption in real time is achieved by smart meters.
another accident if they raised the power all the way because of a problem with
On August 14th, 2003, a major blackout swept across portions of the northeastern United States and Canada. It was reported that a series of equipment outages in the Midwest led to uncontrolled cascading outages of power transmission lines and generators serving parts of the Northeast, Midwest and Canada. Automatic protective systems operated to open circuits and shut down power plants to prevent further spread of the outages. This is very similar to what happened in The Great Northeast Blackout of 1965. In both situations, the “grid system” shut down one generator in line at a time to protect a surge from the station before it.
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.
Throughout the semester, we have watched three films all in which there has been some sort of resistance to power. Cool Hand Luke, directed by Stuart Rosenberg in 1967, was a movie in which the main character, Luke, played by Paul Newman, has been forced to conform to a life in prison. Afterschool, directed by Antonio Campus, is about a boy named Robert, played by Ezra Miller, who is a sophomore in a prep school who happened to catch two girls overdosing on video. The Matrix, directed by Andy Wachowski in 1999, is about a guy named Neo, played by Keanu Reeves, who is a computer programmer by day and a hacker by night. Although these three movies have completely different plots, they all somewhat relate in a way that the main character in each movie struggles with the resistance of power.
It also requires a protection system in which the sources are interfaced using power electronics, so it definitely needs unique protective solutions to provide functionality. [CERTS03]
· 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.
The importance of an electrical lineman is huge, not only in the community but also in most of the world. Their education, training, and correct use of equipment help them in their different and dangerous work conditions to accomplish the tasks of providing power to their communities.
in any group of people, and there will be struggle to achieve it--be it a
...tner of this electricity plant. That will definitely decrease our profits and control but it will assure the constant power demand by these industries. Thus we can reduce our external threats through this step. These industrialists will also help financially in our expansion plan and give us better goodwill in the market.
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.