mellanspännings

Mellanspänning (Swedish for "medium voltage") denotes the range of electrical voltages used for power distribution between low-voltage consumer systems and high-voltage transmission networks. The term is used in utility practice and standards to describe voltages above the low-voltage level (around 1 kV) and below the high-voltage level; exact numerical boundaries vary by country and standard but typically lie in the kilovolt range used for local and regional distribution.

Mellanspänningsnät (medium-voltage networks) carry power from substations to distribution transformers that step voltage down for residential, commercial and some industrial users. Common applications include urban and rural distribution, industrial supply, and specific services such as railway traction. Typical equipment includes medium-voltage switchgear, circuit breakers, transformers, protective relays, overhead lines and insulated cables designed for the applied voltage class.

Design and operation emphasize reliability, fault protection and safety. Protection systems isolate faults to limit outages and equipment damage, while grounding and insulation practices reduce risks to personnel and the public. Maintenance and testing (insulation testing, thermal imaging, fault location) are routine to ensure system integrity.

Regulation and technical requirements are governed by national and international standards (for example IEC standards), which define voltage classes, testing procedures and safety measures. The exact configuration and nominal voltages of mellanspänningsnät differ between countries and historical network designs.