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Electrostatic Breakdown

January 24th Fact-of-the-Day

The 'static' part of the term 'electrostatic' implies an electric field that doesn't change. A 30kV per centimeter static electric field is required to breakdown air dielectric at a standard temperature of 25 degrees C and pressure of 760mm hg. More electric field is required at higher air pressures and less is required at lower air pressures. However, the amount of voltage required to have a 30kV per centimeter electric field depends on the shape and size of a charged surface. For the simple case of spherical charged surface, the electric field at the surface is equal to the surface voltage divided by the sphere's radius. Because electric field strength is inversely proportional to sphere radius, the breakdown voltage is higher for large spheres than for small ones. Consequently, to stop electrostatic breakdown, drop the voltage, increase the air pressure, or increase the diameter of a spherical surface where breakdown is occurring. ©2005 Martek, International. All rights reserved.


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