Mellomspenning

Mellomspenning is the Norwegian term for medium voltage in electrical power systems. It denotes the voltage level between low voltage (lavspenning) and high voltage (høyspenning) and is used primarily in distribution networks to carry electricity from substations to consumers and industrial facilities.

The exact range varies by country, but mellomspenning generally covers roughly 1 kV up to tens of kilovolts, with common distribution voltages such as 10 kV, 20 kV and 33 kV in many Nordic and European networks.

Networks at this level use equipment designed for higher insulation and greater clearance than low voltage, including MV overhead lines, MV cables, switchgear, and transformers that step the voltage down to LV for end users. Substations at mellomspenning serve local feeders and industrial customers, enabling efficient delivery of power while maintaining manageable fault levels and protection schemes.

In Norway and other Nordic countries, mellomspenning is a core part of the electricity distribution system. Design and operation follow national standards and international guidelines for voltage ratings and safety, such as EN/IEC practices and national NEK standards. Ongoing developments focus on reliability, protection coordination, and grid modernization, including integration with smart-grid technologies to improve monitoring and control.