CableGuardian Identifies Weather-Dependent Faults for Network Rail
August 9, 2024
When Network Rail Wales & Western Region faced a weather-dependent insulation resistance fault in its Signalling Power System, CableGuardian delivered intelligence installed. By enabling real-time, feeder-level monitoring, the team quickly identified the issue and implemented a targeted repair—eliminating uncertainty and reducing disruption.
The Challenge: Weather-Dependent Insulation Resistance Faults in Rail Infrastructure
Network Rail’s Signalling Power System (SPS) in the Wales & Western Region consists of four feeders spanning over 44km. The system experienced intermittent low insulation resistance (IR) readings—but only during wet weather conditions.
With the existing Tier 3 Insulation Monitoring Device (IMD), identifying the faulty feeder would have required manual isolation and testing of each feeder. This process depended heavily on timing and luck, as testing needed to coincide with wet weather conditions to capture the fault—making fault-finding inefficient, disruptive, and unreliable.
Sub-Network Section IR Measurement Captured using Temporary CableGuardian ‘Roaming’ Units.
The Viper Solution: CableGuardian for Real-Time Fault Detection and Feeder Monitoring
To improve visibility and speed up fault identification, Network Rail deployed CableGuardian in a Tier 2 configuration at the Principal Supply Point—bringing intelligence installed to the SPS:
- Continuous monitoring of individual feeders replaced a single network-wide IR value.
- Real-time data was accessible through the CableGuardian portal.
- Pre-configured system engineering allowed rapid deployment of additional “roaming” CableGuardian units for targeted investigations.
When wet weather conditions returned, the drop in network insulation resistance was immediately visible. The portal quickly identified the feeder with the lowest IR—narrowing the issue to a single 14.5km section.
By deploying roaming units along this feeder and combining real-time data with targeted field actions, the team systematically pinpointed the fault location.
Results & Benefits: Faster Fault Identification and Targeted Repairs
- Rapid identification of a weather-dependent fault without reliance on manual timing.
- Pinpointing of a faulty cable joint within a specific feeder section.
- Elimination of unnecessary testing across unaffected feeders.
- Reduced disruption and improved efficiency in fault-finding operations.
The faulty cable joint was confirmed to be shorting to earth. The affected section was isolated and re-fed to maintain supply, enabling a planned repair. A new cable section and joints were installed, restoring insulation resistance to acceptable levels and maintaining feeder IR consistently above 1MΩ—regardless of weather conditions.
Intelligence installed in Action
With CableGuardian, Network Rail transformed a complex, weather-dependent issue into a clear, manageable task. By embedding intelligence installed into the signalling power system, engineers moved from reactive, condition-dependent testing to a proactive, data-driven approach—reducing uncertainty, improving reliability, and enabling faster, more effective maintenance decisions.