Dielectric System Characteristics

The dielectric system properties of insulating materials, which manifest themselves in properties such as permittivity, dissipation factor, conductivity or polarization behavior, have strong influences on the formation of electric fields in insulation systems. Starting point of the considerations is the description of fundamental polarization behavior of dielectrics in the time domain and in the frequency domain. Quantities that are deduced from that are permittivity, dissipation factor and complex permittivity, which are relevant for AC fields. Also, conductivity and polarization behavior being relevant for DC fields and transient fields can be deduced. Normally, these properties depend on parameters such as temperature, field stress, frequency or water content, and they are significantly different for gases, liquids and solids. For a description of dielectric properties in accordance with system theory, the classic parallel and series equivalent circuits, polarization current curves, permittivity and dissipation factor spectra, linear and non-linear material equivalent circuits as well as multi-physics approaches are used. Inhomogeneous dielectrics must be described by spatial discretization.