Electrical field distribution (AC/DC)

Electrical field distribution at epoxy resin/air interfaces under direct current

The demands on power supply systems are constantly growing. This is due in part to the increasing distances between renewable energy systems and consumers, and also to further technical advances in energy conversion. High-voltage direct current (HVDC) gas-insulated switchgear (GIS) and gas-insulated lines (GIL) offer tremendous development potential for achieving compact, low-loss, reliable power distribution and transmission.

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Encapsulated systems for HVDC

While gas-insulated systems for use under alternating current have been state of the art for several decades, developing encapsulated systems for HVDC is extremely challenging. From an electrical standpoint, the design and chemical composition of the installed post insulators and insulating partitions are key to this new generation of systems.  

For applications under alternating current, the electrical field is distributed as a function of the relative permittivity of the dielectric material. Under HVDC, the orientation of the field lines depends on the electrical conductivity of the inert gas, the volume of insulation material, and the material’s surface. Controlled by the direction of these field lines, the electrical charge carriers flow and can accumulate on the insulation surface. The local accumulation of charge carriers and the temporal characteristics of charge buildup and decay depend on various physical effects that form the basis for the latest numerical simulations.

Physical influencing variables

Ionization through natural radiation, emission from metallic surfaces, recombination and accumulation effects between the charge carriers

Convective distribution as a function of the electrical field, diffusion of charge carriers resulting from differences in concentration, charge accumulation and conduction at dielectric interfaces, nonlinear charge transport in the insulation material volume

Superimposition of a capacitative surge (lightning stroke, failure) on resistively charged systems, examination of resulting field displacement

Heat generation through ohmic losses at the inner conductor, temperature distribution through convection currents, conduction, and radiation


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Determining the thermal behavior of products and systems saves production costs and enables an efficient product development. Besides the electrothermal simulation, Siemens also offers a comprehensive know-how all around structural and mechanical design and electrical field simulation (AC/DC). Contact us and we’ll find solutions to your specific problems.