The age during which convenient and abundant fossil energy resources were available to build new technologies and to support a sustained energy world transition is short.Renewable energy and methodologies have a clear role in future energy policy. Governments decided to develop aggressive long term actions that can accelerate the widespread applications of renewable energy and to get on a firm path toward a worldwide “renewable energy transition”; according to this policy 20% of world electricity production should come from renewable energy sources within 2020. Renewable energies are potential resources to provide society with efficient and environmental friendly energy. Renewable technologies clearly reduce air pollution and greenhouse gas emission and, in addition, improve the security of energy by diversifying and decentralizing energy supply, reducing the dependence to fossil fuel sources. Besides, renewable energy technologies form a dynamic sector which provides economic growth and jobs for our economies.
An insulator or dielectric is a substance within which there are no mobile electrons necessary for electric conduction. However, when the voltage applied to such an insulator exceeds a certain value, then it breaks down and allows a heavy electric current (much larger than the usual leakage current) to flow through it. If the insulator is a solid medium, it gets punctured or cracked. The disruptive or breakdown voltage of an insulator is the minimum voltage required to break it down. Dielectric strength of an insulator or dielectric medium is given by the maximum potential difference which a unit thickness of the medium can withstand without breaking down. In other words, the dielectric strength is given by the potential gradient necessary to cause breakdown of an insulator. Its unit is volt/meter (V/m) although it is usually expressed in KV/mm. For example, when we say that the dielectric strength of air is 3 KV/mm, then it means that the maximum PD which one mm thickness of ...
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