A dielectric or dielectric material is an electrical insulator or a very poor conductor of electric current. When dielectrics are placed in an electric field, electric charges do not flow through the material as they do in an electrical conductor such as metal, but only slightly shift from their average equilibrium positions causing dielectric polarization. As a result of dielectric polarization, positive charges are displaced in the direction of the field and negative charges shift in the opposite direction. This causes an internal electric field that reduces the overall field within the dielectric itself.

Most dielectric materials are solid. Some examples include porcelain (ceramic), mica, glass, plastics, and the oxides of various metals. Although solid dielectrics are the most commonly used dielectrics in electrical engineering, some liquids and gases can also serve as good dielectric materials. Dry air is an excellent dielectric, and is used in variable capacitors and some types of transmission lines. Distilled water is a fair dielectric. A vacuum is an exceptionally efficient dielectric.

Dielectric materials have the properties of low conductance (high impedance) and low loss. One popular technique for analyzing such materials is Dielectric Impedance Spectroscopy - measuring the electrical impedance over a range of frequencies. The impedance is related to the conductivity and capacitance of the material, and these parameters can in turn be related to the molecular activity of the material. However, analyzing low conductivity, low loss materials is beyond the capability of most impedance analyzers.

Rotalab provides specialized dielectric/impedance analyzers that can cope with ultra-low current and capacitance levels experienced in testing dielectric materials.

  • 1296A
    Dielectric Interface System

    Dielectric Interface System
    Dielectric Impedance Analyzer