One of the oldest transmission lines in Slovenia, the 110 kV Divača–Pivka–Ilirska Bistrica line, is retiring after 84 years of operation. This vital element of the southern Primorska region’s power infrastructure was built on the eve of World War II and is now receiving a fully modernized successor.
Project overview
The transmission line route spans 30 kilometres and represents a key connection between Divača, Pivka and Ilirska Bistrica. The project involves complete dismantling of the old line and construction of a new double-circuit 110 kV transmission line along the same route.
Work is designed to be executed with minimal system outages, which is a major technical challenge due to proximity to live lines. The entire project is expected to be completed by the end of 2025.
In addition to increasing energy reliability, the project includes upgrades to protection systems, enabling improved monitoring and fault prevention, reducing the time needed for interventions and maintenance.
Technical characteristics
- Transmission line voltage: 110 kV
- Total route length: 30 km
- Line type: Double-circuit
- Number of new towers: 166 steel lattice towers, replacing old concrete structures
- Installation of a full safety climbing system across the entire route
- Application of anti-corrosion protective coating across the whole project
Implementation challenges
- Complete dismantling of the old transmission line while maintaining grid stability
- Installation of steel tower structures and performance of electromechanical works on the 2×110 kV Divača–Pivka section
- Installation of steel tower structures and electromechanical works on the 2×110 kV Pivka–Ilirska Bistrica section
- Working near live voltage, requiring enhanced safety measures
- Replacement of old towers and optimization of the route to improve transmission efficiency
- Maintaining minimal outages to ensure uninterrupted supply for local communities and industrial consumers
- Work on complex terrain, including sections with difficult geological conditions
- Synchronization with existing infrastructure to ensure maximum compatibility with the new installations with the grid
Elnos Group’s role
Elnos Group is responsible for the following tasks:
- Complete dismantling of the old 110 kV transmission line
- Construction of new sections of the 110 kV line along the existing route
- Installation of new towers and cable systems
- Optimization of protection equipment and remote-monitoring systems
- Testing and commissioning of the new transmission line to ensure full operational capability
- Installation of OPGW optical cables to enhance communication and remote monitoring of the power network
- Integration of new automated grid-management systems for faster response to potential faults or outages
Strategic importance
- Improvement of power-grid stability for Slovenia’s southern Primorska region, as well as reinforcement of cross-border transmission links, since TS Divača forms a key connection point between the grids of Italy, Slovenia and Croatia
- Increased capacity and reliability of electricity transmission
- Long-term reduction of network losses, contributing to greater energy efficiency
- Support for Slovenia’s transition toward a more modern and resilient power system
- Increased grid resilience to weather events and environmental impacts
- Creation of conditions for integration of renewable-energy sources, enabling further development of green power in the region
Reconstruction of the 2×110 kV Divača–Pivka–Ilirska Bistrica transmission line represents a key infrastructural achievement for Slovenia. The project not only modernizes the existing system but also ensures long-term efficiency and resilience, alongside improved monitoring and power-system security.
