Urban power networks are changing rapidly. As electrification accelerates and cities become more densely built, underground transmission cables are taking on a much greater role in maintaining reliable power supply.
While this shift brings clear advantages, it also introduces new operational challenges. Faults are harder to detect, slower to locate and significantly more disruptive to resolve. In this context, visibility across underground assets is becoming just as important as capacity.
Underground cables are often seen as a more resilient alternative to overhead lines. They are less exposed to extreme weather, reduce visual impact and improve safety in urban environments.
However, when issues arise, the complexity increases significantly. Cables are typically installed in long sections beneath roads and infrastructure, meaning that even identifying the location of a fault can require extensive investigation. Repair work often involves excavation, permits and coordination with local authorities, all of which extend timelines and increase costs.
In dense urban settings, even short interruptions can have a disproportionate impact. Critical infrastructure, commercial operations and connected systems all rely on continuous power availability. As a result, the cost of uncertainty is high.
Most failures in high voltage cable systems are not sudden. They are preceded by gradual insulation degradation, which manifests as partial discharge activity. These early signals provide a valuable indication that a fault is developing.
Historically, detecting and interpreting these signals has depended on specialist expertise. Engineers are deployed to analyse available data, but pinpointing the exact origin of a discharge can be difficult. Signals can propagate along the cable, and different fault types can produce similar signatures, making diagnosis both time-consuming and uncertain.
This approach inevitably leads to reactive maintenance, where action is taken only once the problem has become more severe.
Permanent, online monitoring of partial discharge is enabling a shift towards continuous awareness of asset condition. Instead of relying on periodic inspections or post-failure analysis, operators can observe the behaviour of their network in real time.
This changes the role of data within grid operations. Partial discharge is no longer just a diagnostic signal, but a continuous source of insight into insulation health, fault development and system performance.
With the right analytical approach, it becomes possible to identify the type of defect, determine its severity and locate it with precision, all before it develops into a critical failure.
Accurate fault detection is only part of the equation. The real value lies in enabling targeted intervention.
When the location and nature of a fault are clearly understood, maintenance can be planned with far greater precision. This reduces the need for extensive excavation, shortens repair timelines and limits disruption to surrounding infrastructure.
In practical terms, this means fewer unexpected outages, faster resolution when issues occur and a more efficient use of operational resources.
As transmission networks continue to evolve, monitoring is increasingly being integrated from the outset rather than added later. In some regions, digital monitoring capabilities and connected technologies are becoming a prerequisite for new infrastructure.
This reflects a broader shift towards grids that are not only more powerful, but also more aware of their own condition. Continuous monitoring supports more informed decision-making, better prioritisation of maintenance and a more resilient overall system.
The expansion of underground transmission is set to continue, driven by urbanisation, electrification and the need for more robust infrastructure.
In this environment, permanent partial discharge monitoring offers a practical way to improve visibility and reduce risk. By enabling earlier detection, more accurate diagnosis and better planning of interventions, it supports a more reliable and efficient network.
Understanding what is happening below the surface is no longer optional. It is becoming a fundamental requirement for managing modern power systems.
You can no longer participate in this event but you can access its recording