Isolationsspænding

Isolationsspænding, also known as dielectric strength or breakdown voltage, refers to the maximum electric field strength that a material can withstand without undergoing electrical breakdown. In simpler terms, it is the voltage at which an insulating material fails and begins to conduct electricity. This phenomenon is crucial in the design and application of electrical equipment, as it dictates the safe operating limits for insulation.

When an electric field is applied across an insulating material, the electrons within the material are subjected to a force. If this force becomes strong enough, it can overcome the binding forces holding the electrons to their atoms. This can lead to a rapid increase in conductivity as free electrons are generated and accelerated, causing an avalanche effect and ultimately, material failure.

The isolationsspænding of a material is typically measured in volts per unit thickness, such as kilovolts per millimeter (kV/mm). It is influenced by several factors, including the type of material, its temperature, humidity, the presence of any defects or impurities, and the duration of voltage application. Different insulating materials have vastly different isolationsspænding values, with some, like certain ceramics, exhibiting very high resistance to electrical breakdown, while others, like air, have significantly lower values. Understanding and respecting the isolationsspænding of materials is paramount for ensuring electrical safety and preventing equipment damage.