Fault-current and protection management:
expanding applications for RSFCL technologies
in AC and DC networks 

Fault-current and protection management was a recurring topic throughout CIGRE 2026, reflecting the growing constraints faced by both AC and HVDC networks. The discussions observed across technical sessions, workshops and industry exchanges suggest a change in perspective: the focus is shifting from the performance of individual components towards their contribution to network-level architectures.
Among the technologies attracting attention, resistive superconducting fault current limiters (RSFCLs) are being evaluated across a widening range of applications, from AC substations to future HVDC protection schemes and DC switching stations. 

A visible trend at CIGRE 2026 was the growing emphasis on higher short-circuit withstand capabilities. Several manufacturers showcased equipment designed for fault-current levels approaching 80 kA, highlighting the challenges created by greater network interconnection, rising power demand and the multiplication of grid connection points. 

For TSOs (transmission system operators), the issue extends beyond the performance of individual assets. As fault levels rise, existing substations can progressively approach the limits of their installed equipment. Upgrading switchgear ratings remains one possible approach, but it often involves significant investment and may become difficult to implement in constrained environments. 

This context continues to drive interest in fault-current limitation technologies. Rather than increasing the rating of every affected component, limiting the fault current at strategic locations can help contain short-circuit levels while preserving existing infrastructure. 

Beyond AC applications, discussions within Study Committee B4 confirmed growing interest in the role that fault-current limitation could play within future HVDC protection schemes. As HVDC projects move towards larger point-to-point links, multi-terminal systems and, ultimately, meshed architectures, protection remains one of the most challenging aspects of system design. DC circuit breakers are widely recognised as a key enabling technology, but discussions at CIGRE highlighted continued interest in complementary approaches capable of influencing fault-current evolution before interruption occurs. 

From this perspective, RSFCLs are increasingly being considered as part of a broader protection strategy rather than as standalone devices. By limiting fault-current growth during the first stages of a fault, they may contribute to reducing stresses on other protection equipment and provide additional flexibility when designing protection architectures. 

Several exchanges also highlighted a broader industry trend: network operators are actively exploring a portfolio of protection technologies rather than relying on a single solution. This interest reflects both the growing complexity of future HVDC networks and the relatively limited number of mature fault-current management technologies currently available for DC applications. 

The discussions observed at CIGRE suggest that the question is progressively evolving from component feasibility towards system integration. Attention is focused on where fault-current limitation can deliver measurable benefits within future protection schemes and how it can interact with other protection functions. 

The development of future DC switching stations and DC hubs was another topic where fault-current limitation featured prominently. 

These infrastructures are expected to play a central role in future HVDC grids by providing operational flexibility, network reconfiguration capabilities and improved asset utilisation. At the same time, they introduce new constraints related to fault management and protection coordination. 

In this context, several discussions highlighted the potential value of combining switching functions with fault-current limitation. Rather than relying exclusively on higher-performance interruption capabilities, some architectures aim to control fault-current levels upstream and therefore reduce the overall burden placed on protection equipment. 

This approach has been investigated in studies such as SPRINT, where RSFCL technologies were assessed within broader DC switching architectures. The objective is to explore how fault-current limitation can influence the design, sizing and cost of future HVDC infrastructure. 

Such discussions reflect a broader shift in the industry. Fault-current limitation is being assessed according to the value it can create at network level, particularly in applications where protection requirements have a direct impact on infrastructure complexity and CAPEX. 

The growing attention observed around RSFCL applications also reflects progress across the superconducting ecosystem itself. Advances in superconducting tapes continue to improve the technological foundation on which fault-current limiters are built, while industrial projects are placing greater emphasis on deployment and operational validation rather than proof of concept alone. 

Across utilities, manufacturers and research organisations, discussions at CIGRE 2026 focused less on demonstrating that superconducting fault-current limitation can operate under fault conditions and more on identifying where it can deliver the strongest value. This includes not only future high-voltage AC and DC network architectures, but also emerging applications, for example in data centers.