CableGuardian encompasses proven technology with extensive industrial heritage in challenging environments to provide a distributed and intelligent cable infrastructure health monitoring system for various electrical industries.


With the increasing age of many cables, cable failures are becoming more of an issue. Cables can fail due to various reasons and these are not always detectable using one method or piece of equipment. Repairs and maintenance require systems to be powered down and the fault located which takes time and resources.


CableGuardian is a browser-based condition monitoring and fault finding system for both cable and conductor faults on electrical networks. Its measurement technology is not just your standard insulation monitoring device (IMD). Each sensor unit is comprised of two complementary technologies; an IMD and built-in time-domain reflectometer (TDR) with a difference. The IMD is Viper Innovation’s V-LIM which has been developed for and proven in the harsh conditions experienced by the subsea oil and gas industry. CableGuardian monitors the insulation resistance of the system in addition to other electrical parameters. This information gives the viewer a greater understanding of the status and integrity of the cable, the nature of any changes or emerging faults. What really sets CableGuardian apart is its ability to monitor via multiple independent units on the power network. Their unique proprietary connection method allows the identification of the faulty cable sections without conflicting with one another.

CableGuardian also moves away from traditional TDR which has its limitations, namely an inability to be used on a powered cable. What sets Viper’s TDR apart is the use of digital signals which operate within the noise margins of the powered line. Known as Spread Spectrum Time Domain Reflectometry (SSTDR), small, but nevertheless, recognizable digital signals are sent across a wide range of frequencies, and like traditional TDR, are reflected and correlated against the sent signal to identify the fault type and provide a location, in real-time. SSTDR can be run on energized wires because the signals can be isolated from the host system noise and activity by the sensors and interpreted by the CableGuardian algorithms. Small impedance changes caused by known conditions, like connectors and loads and inherent system noise can be ignored while unplanned events such as hard or intermittent faults are reported. Live monitoring means that events, such as vandalism or theft of cables, can be alarmed and logged as they happen and importantly the exact location of such an event is instantly available.

CableGuardian provides the only solution for top-level Tier 1 adherence to the Network Rail Insulation Monitoring Device standard NR/L2/SIGELP/27725, which recommends monitoring of the cable sections. Additionally, CableGuardian’s real-time monitoring for conductor faults on the copper or aluminium cable cores provides an alternative approach to the intrusive, five-yearly core-to-core testing requirements of the Network Rail NR/L2/SIGELP/50000 standard.

Each CableGuardian transmits data, via a secure internet connection, to the remotely hosted CableGuardian Data Storage and Analytics System which analyses it, and monitors degradation and determines the location of faults on the live power network. The results are displayed clearly, at a glance, on an interactive web portal. Master Users have full control to set the CableGuardian alarm thresholds which send alerts direct to key personnel via the interactive web portal, email, text messages and automated voice messages.

The minimum and maximum distance between CableGuardian nodes in a network depends on the system design, the electrical characteristics of the existing or proposed cables and the type of faults that are to be monitored along with required alarm levels. Please contact Viper for guidance on your specific application.

Developed at the request of Network Rail, CableGuardian supports the ambitions to reduce maintenance costs and time-related E&P infrastructure failures, to reduce the frequency and duration of service affecting failures and to improve the overall asset management process.


  • Railway signalling power distribution systems
  • Mission critical IT (unearthed) electrical distribution systems

Key Benefits

  • Helps to avoid injury and reduce downtime through early fault detection and location
  • Analytics facilitate proactive, rather than reactive, maintenance
  • Enables faster and more accurate repair, minimising service outage
  • Permits a move from a frequency based inspection regime to one driven by actual asset condition and performance
  • Enables compliance with the requirements of Network Rail Standard NR/L2/SIGELP/27725

Key facts

  • Locates the position of insulation failure and further locates with 98% accuracy the precise location of any short, open, or transient failure.
  • Measures insulation resistance, capacitance, shorts, opens and intermittent faults as well as a range of electrical parameters (voltage, current, frequency, power, Polarisation Index, Dielectric Absorption Ratio).
  • Distributed and intelligent infrastructure for cable health monitoring
  • Enables compliance with the requirements of Network Rail Standard NR/L2/SIGELP/27725
  • Integrity alarms and fault information direct to asset stakeholders