Essay on Plastic Pollution: Top 4 Essays Article shared by: Read this essay to learn about plastic pollution. After reading this essay you will learn about:
Annotated Bibliography Introduction Electronic equipment containing transistors, and particularly equipment containing integrated circuits e. These transient overvoltages are commonly caused by lightning and switching reactive loads on the ac supply mains. As a result of the threat and vulnerability, it is good engineering practice to plug every personal computer or other electronic system into a surge suppressor.
In the late s fire investigators became aware that surge suppressors could cause fires. Embassy in Grenada and "a number of fires" elsewhere. In Januaryan employee of the Greensport Yard in Houston arrived at work to find the office full of smoke from a burning surge suppressor, with a second surge suppressor of the same model hot and ready to burn.
These few webpages are just the "tip of the iceberg" of a much larger problem. Few people who have a burning surge suppressor post a webpage about the problem. I am posting this essay to warn the public about fire hazards of surge suppressors, and to make a few practical suggestions to avoid such fires.
While there is a bibliography of technical papers at the end of this essay, I have attempted to minimize the amount of technical information in the text of this essay.
There are now at least a half-dozen manufacturers of metal-oxide varistors in the world. The development of metal-oxide varistors coincided with the widespread adoption Hazards of plastics essay vulnerable electronic equipment e.
Varistors connected to the ac supply mains are normally nonconducting.
When a transient overvoltage occurs, varistor s become conducting and divert surge current away from the vulnerable equipment downstream, as well as limit the magnitude of the surge voltage. More than varistors were sold worldwide in The varistor itself is a ZnO ceramic, which does not burn.
However, continuous conduction of the varistor can cause the epoxy coating on the outside of the varistor to burn like a candle. At somewhat lower power dissipation in the varistor, the varistor may become hot enough to melt plastics in the vicinity of the varistor.
Under some conditions, flammable plastics might be ignited by a hot varistor or by the burning epoxy coating on a varistor.
This is the smallest MCOV rating that will not conduct on normal utility voltage. The advantage of using varistors with this smallest MCOV rating is that it also gives the lowest voltage protection level sometimes called "clamping voltage" in the USA during a surge.
Arguably, the lowest voltage protection level during a surge puts less stress on the equipment downstream from the surge suppressor. Some engineers have criticized UL for including this performance rating in their tests, which are supposedly confined to safety considerations.
However, without this UL voltage protection rating, manufacturers would still be clamoring for the lowest possible voltage protection level, and the claims between competing manufacturers would be at different peak surge currents or different surge current waveshapes, thus precluding meaningful comparisons by consumers.
VN is generally considered the boundary between the nonconducting and conducting states of the varistor: There are long-duration surges i. Opening of fuses in the utility distribution system is one cause of such long-duration surges; another cause is switching of power-factor correction capacitors in the utility distribution system.
Varistors are designed and intended only for protection against transient overvoltages with a duration less than a millisecond, not for regulation of the continuous, sinusoidal utility voltage!
For many years, designers of surge suppressors simply assumed that the lowest voltage protection level would give the best protection to the equipment, without being aware that there were other considerations e.
The selection of the MCOV rating of the varistor is important, not only for ability to avoid fires caused by disturbances of the voltage on the ac supply mains, but also because of the need to coordinate a surge suppressor with an upstream surge arrester.
Coordination is discussed in the next section of this essay. Such a large MCOV rating of the surge suppressor can still be accompanied by low voltage protection levels inside the building, as discussed later in this essay.
Both surge arresters and surge suppressor are members of the class of surge-protective devices SPDs. Engineers who design surge-protective devices seem to assume that their products will be used alone in a building.Free recycling papers, essays, and research papers. Recycling: A New Form Of Recycling - Any person, who sees a cigarette butt on the ground or anyone, who has community service, can pick up cigarette butts and put them in these bins.
What you have here on this website is a description of how all commerce and industry will be designed in, let’s say, a hundred years. There is no alternative.
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Any opinions, findings, conclusions or recommendations expressed in this material are those of the authors and do not necessarily reflect the views of UK Essays. Objective: To examine the concept of food miles and the environmental consequences of increasing volumes of air freight.
Food miles refer to the distance that food travels from where it is produced to where it is consumed. The term was introduced in London in the 's by a professor at London City University when discussing sustainable agriculture.
This article provides information about Plastic hazards! Plastic is widely used in our day to day life. Starting from a pen to a polythene bag in which we carry fruits and books are forms of plastic.
Though convenient in our day to day use, it has posed an alarming threat to the environment. Plastic.