On electric strength of solid insulating materials

A simple equation of the form E=-A+B log₁₀ (ρ_v)/(ε_r)·(tan δ) 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 ρ_v, relative permittivity ε_r, and dissipation factor tan δ 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<t<0.52 mm