On electric strength of solid insulating materials

A simple equation of the form E=-A+B log/sub 10/ ( rho /sub v/)/( epsilon /sub r/).(tan delta ) to predict the electric strength of a solid insulating material using the ASTM electrode system has been proposed. The constant B has been obtained as a function of the thickness t of solid insulating materials. The equation requires the values of volume resistivity rho /sub v/, relative permittivity epsilon /sub r/, and dissipation factor tan delta of the material, which may be obtained easily by low-voltage nondestructive measurements. The values of electric strength calculated using this equation for polyethylene, fiberglass, leatheroid, mica, empire cloth, and polyethylene-coated leatheroid show an excellent agreement with the experimentally measured values when 0.15 mm>