How Telemark Nett Enhanced Grid Safety with Safegrid
Background
Telemark Nett, a regional grid operator in Norway, manages a 66kV transmission network that traverses rugged terrain and densely forested areas. This geography, combined with the region’s unpredictable weather, makes maintaining grid reliability a challenge. During a recent windstorm, Telemark Nett encountered a series of intermittent and transient earth faults — subtle but potentially dangerous disturbances that can be hard to locate.
The Challenge
During one stormy night, Telemark Nett observed several intermittent earth faults in their 66kV system. Protection relays registered multiple fault starts. However, none of these events resulted in tripping, suggesting the faults were short-lived — likely triggered by trees swaying into close proximity with overhead lines.
The affected zone included multiple intersections near the Lio substation, making fault localization particularly difficult. Without clear tripping events or visible damage, identifying the precise cause and location of these intermittent earth faults posed an operational challenge.
Safegrid’s Solution
Using Safegrid’s Intelligent Grid System®, Telemark Nett was able to localize the source of the intermittent earth faults to specific intersections. Safegrid’s data driven analytics combined with sensors, provided real-time insight into fault activity — detecting patterns that traditional protection systems alone could not distinguish.
The system not only confirmed that the faults were real, but also helped isolate which areas stood out due to the frequency and strength of the events. This allowed Telemark Nett’s grid operators to direct their field crews to the most probable fault locations — significantly reducing time and effort spent on manual inspection.
The Result
Upon visiting the highlighted areas, field crews found several trees growing close to the 66kV lines. Though the trees hadn’t yet caused permanent contact, the wind had pushed branches close enough to induce intermittent earth faults throughout the night. These faults had triggered earth-fault protection on the relays, but not strong enough to trip — a classic scenario where Safegrid’s precise monitoring proved invaluable.
“Safegrid’s system gave us a level of visibility we simply didn’t have before. We were able to find and address a potential hazard before it escalated. That’s a major win for operational reliability.”
— Torfinn Heggtveit, Operation Engineer, Telemark Nett
Conclusion
This case underscores the value of intelligent monitoring in dealing with complex fault scenarios such as intermittent and transient earth faults. In environments where traditional protection relays might register a start but not trip, Safegrid delivers the next layer of insight — empowering grid operators like Telemark Nett to take informed, preventive action.
