Search results
Results From The WOW.Com Content Network
The field strength at which break down occurs is an intrinsic property of the material called its dielectric strength. In practical electric circuits electrical breakdown is often an unwanted occurrence, a failure of insulating material causing a short circuit , resulting in a catastrophic failure of the equipment.
In electromagnetism, a dielectric (or dielectric medium) is an electrical insulator that can be polarised by an applied electric field.When a dielectric material is placed in an electric field, electric charges do not flow through the material as they do in an electrical conductor, because they have no loosely bound, or free, electrons that may drift through the material, but instead they ...
Dielectric breakdown within a solid insulator can permanently change its appearance and properties. As shown in this Lichtenberg figure. A disruptive device [citation needed] is designed to electrically overstress a dielectric beyond its dielectric strength so as to intentionally cause
A liquid dielectric is a dielectric material in liquid state. Its main purpose is to prevent or rapidly quench electric discharges . Dielectric liquids are used as electrical insulators in high voltage applications, e.g. transformers , capacitors , high voltage cables , and switchgear (namely high voltage switchgear ).
The relative permittivity (in older texts, dielectric constant) is the permittivity of a material expressed as a ratio with the electric permittivity of a vacuum. A dielectric is an insulating material, and the dielectric constant of an insulator measures the ability of the insulator to store electric energy in an electrical field.
For high voltage applications, a good dielectric gas should have high dielectric strength, high thermal stability and chemical inertness against the construction materials used, non-flammability and low toxicity, low boiling point, good heat transfer properties, and low cost. [1] The most common dielectric gas is air, due to its ubiquity and ...
Insulators made from porcelain rich in alumina are used where high mechanical strength is a criterion. Porcelain has a dielectric strength of about 4–10 kV/mm. [8] Glass has a higher dielectric strength, but it attracts condensation and the thick irregular shapes needed for insulators are difficult to cast without internal strains. [9]
In electrical engineering, a dielectric withstand test (also pressure test, high potential test, hipot test, or insulation test) is an electrical safety test performed on a component or product to determine the effectiveness of its insulation. The test may be between mutually insulated sections of a part, or energized parts and ground.