ÜNB

ÜNB stands for Übertragungsnetzbetreiber, the operator of a country’s high‑voltage electricity transmission network. ÜNBs are responsible for the secure and reliable transmission of electricity, balancing supply and demand, maintaining frequency and voltage stability, and planning and developing the grid to accommodate future generation and loads.

Core duties include real-time grid operation and outage management, provision of balancing services and reserves, management of interconnections and cross-border power flows, market facilitation such as capacity allocation and grid access rules, and ensuring transparency of grid data for market participants and regulators.

Regulatory framework and supervision: In the European Union, ÜNBs operate under national regulation and EU network codes and guidelines. ENTSO‑E coordinates cross-border issues among European transmission system operators, while ACER oversees cross-border aspects at the European level. ÜNB independence from generation and retail activities is a common requirement, with oversight by national regulators.

Ownership and structure: ÜNBs are typically regulated monopolies within their jurisdictions and may be owned by public authorities or private entities. They are required to operate independently from generators and suppliers and to recover costs through regulated tariffs or price controls set by national regulators. Their governance and business practices must align with market rules, grid codes, and transparency standards.

Examples: In Germany, the four ÜNBs are 50Hertz, Amprion, TransnetBW, and TenneT TSO GmbH. Austria operates Austrian Power Grid (APG) as its ÜNB. Switzerland’s ÜNB is Swissgrid. The concept of ÜNB applies across many European countries, each with its own national operator.

See also: transmission system operator, ENTSO‑E, ACER, network codes.