Introducing Essential Services of Critical Infrastructure: Operation, Maintenance and Development of the Electricity Transmission System

Many people confuse the electricity transmission system with the electricity distribution system, although their functions are fundamentally different. The electricity distribution system delivers electricity to end users, including households, businesses, hospitals, schools and public institutions. The electricity transmission system, on the other hand, provides the long-distance transfer of electricity between power generation facilities, transmission substations, electricity distribution systems and interconnected foreign electricity systems.

From an energy-sector perspective, these are not two separate systems but rather two interconnected parts of a single electricity network. The transmission system provides electricity transmission at the national and international interconnection level, while distribution systems deliver electricity to specific end users.

Simply put, electricity generated in nuclear, hydroelectric or thermal power plants first enters the transmission system. It is then transferred to distribution systems, which distribute it to cities, municipalities, businesses and households. Without a reliable transmission system, neither the operation of distribution systems nor the stable supply of electricity to consumers would be possible.

The Electricity Transmission System within the Structure of the Energy Sector

For easier reference, the following table presents the position of this essential service within the energy sector according to Annex No. 1 of Act No. 367/2025 Coll. on Critical Infrastructure:

 Sector: Energy

 Subsector: Electricity

 Category of Entities: Transmission System Operators under Special Legislation

 Essential Service: Operation, Maintenance and Development of the Electricity Transmission System

 Competent Authority: Ministry of Economy of the Slovak Republic

This is an essential service whose disruption could significantly affect the functioning of the entire electricity sector. A major outage of the transmission system would have consequences not only for individual regions of Slovakia but also for the operation of electricity distribution systems and cross-border energy interconnections.

Why Is This Service Important?

One of the specific characteristics of the electricity sector is the need to continuously maintain a balance between electricity generation and consumption.

The transmission system plays a crucial role in maintaining this balance. In Slovakia, it comprises approximately 3,000 kilometres of extra-high-voltage transmission lines and dozens of strategic substations. Every second, thousands of megawatts of electricity flow through the system, supplying more than 5 million inhabitants of the Slovak Republic.

The importance of the transmission system is also increasing due to the development of renewable energy sources, the growth of electromobility and the gradual electrification of industry. Every new large-scale generation facility or major electricity consumer places additional demands on the system’s capacity and stability.

Competent Public Authority

The competent public authority for the energy sector and electricity subsector is Ministry of Economy of the Slovak Republic.

The Ministry of Economy of the Slovak Republic designates critical infrastructure entities, assesses risk analyses and security plans submitted by operators, and coordinates the sector during emergency situations.

Entities Providing the Essential Service

According to Annex No. 1 of Act No. 367/2025 Coll., the essential service of operation, maintenance and development of the electricity transmission system is provided by transmission system operators under special legislation, namely Act No. 251/2012 Coll. on Energy.

Within the territory of the Slovak Republic, this role is performed by:

Slovenská elektrizačná prenosová sústava, a.s. (SEPS)

The transmission system operator is responsible for the safe, reliable and efficient operation of the transmission system, managing electricity flows, providing system services, planning system development, and coordinating with distribution system operators and international partners.

This infrastructure is of strategic importance, and its operation directly affects the stability of the entire electricity system of the Slovak Republic.

Specific Characteristics of Transmission System Operation

The electricity transmission system differs from electricity distribution systems not only in its function but also in the scope of its responsibilities.

While distribution systems deliver electricity to specific customers within individual regions, the transmission system ensures the stability of the electricity system as a whole. As a result, it operates continuously, 24 hours a day, 7 days a week.

Dispatch centres monitor transmission lines, substations, system frequency, power flows and international interconnections in real time. Even minor deviations may indicate an emerging problem requiring immediate action.

International cooperation is also of particular importance. The Slovak transmission system forms part of the synchronized Continental European electricity system. This means that events occurring in one country may affect system stability in other European countries as well.

Maintenance and Development: An Investment in Energy Security

The reliability of the electricity transmission system requires continuous maintenance and long-term investment.

Regular activities include:

- inspections of extra-high-voltage transmission lines,

- diagnostics of transformers and substations,

- modernization of obsolete technological equipment,

- replacement of components at the end of their service life,

- digitalization and automation of system management.

Many assets are designed to operate for several decades. Their safety and reliability therefore depend on systematic renewal and modernization.

The development of the transmission system is also essential for connecting new electricity generation facilities, expanding cross-border transmission capacities and meeting growing demands for electricity transmission.

Risks and Security Challenges

The electricity transmission system is one of the most important components of the state's critical infrastructure and therefore faces a broad spectrum of threats.

The most significant risks include:

- cyberattacks targeting control and dispatching systems,

- physical damage to transmission lines or substations,

- extreme weather events,

- technological failures,

- ageing infrastructure,

- shortages of qualified professionals,

- dependence on specialized supply chains.

With the increasing digitalization of the energy sector, particular attention is being paid to protecting control systems and strengthening cyber resilience.

The Critical Infrastructure Association of the Slovak Republic as a Partner for Energy Infrastructure Operators

Operators of critical energy infrastructure today face a combination of legislative requirements, technological changes and security challenges. The Critical Infrastructure Act introduces new obligations related to risk analyses, security plans, the designation of responsible persons and incident management.



The Critical Infrastructure Association of the Slovak Republic therefore provides a platform that connects critical infrastructure operators, experts, technology partners and professional organizations. The Association offers methodological support, facilitates the exchange of experience, provides expert opinions on forthcoming legislation and promotes practical solutions for enhancing the resilience of critical infrastructure.