DNV KEMA Smart Cable Guard®

Continuously monitoring the ‘heartbeat’ of an MV cable connection

We use energy every day without thinking about it; we take the energy supply for granted. But how reliable is our energy supply? Blackouts show us how vulnerable we are if the energy is not there. For affected businesses, power failures can have serious economic consequences. If the IT systems go down, for example, the cost can easily run into millions. In recent years, major failures have hit places such as New York, London and Italy, bringing daily life to a complete standstill.

Medium-voltage networks are crucial to the energy supply. However, many of the MV networks currently in use are aging and/or have weak spots, such as joints and terminations, which increase the blackout risk. To address this risk, network operators can perform preventive checks in the form of periodic off-line snapshots. Such precautions are valuable, but a problem affecting a joint or cable can build up to a critical level within just days or weeks. So the only way to assure prompt intervention is continuous monitoring.`

Project
DNV KEMA has introduced a unique, innovative system called DNV KEMA Smart Cable Guard®, which continuously listens to the ‘heartbeat’ of an MV cable by monitoring and locating partial discharge activity. At each end of the cable, a sensor and a control unit are installed to measure partial discharge (PD) activity along the entire length of the cable connection while it is in use. The measurements are sent by GPRS to our control center, where they are analyzed and interpreted. When critical PD values are detected, details of the defect location are sent to the network operator, together with advice about what should be done. The network operator can then take precautionary action such as redirecting the power or placing a generator set to secure the supply before doing the necessary repairs. In this way, the operator can avoid the adverse media reports, unhappy customers and possible compensation claims liable to result from a blackout. A continuous flow of information about the condition of the cable network also provides the owner with a basis for optimized replacement and maintenance strategies and efficient risk management. This means previously unavailable insight into the behavior of MV cables and accessories.

Benefits
> Continuous access to MV network status information
> Early warnings and advice about appropriate action
> Indicative distance-to-defect information
> Reduction and distribution of maintenance costs
> No need to interrupt power during installation or daily use
> Prevention of negative publicity and claim reduction
> Public image enhancement: innovative and reliable grid management

Project coordinator
> DNV KEMA, the Netherlands

Project partners
> Alliander, the Netherlands
> Eindhoven University of Technology, the Netherlands
> Enexis, the Netherlands
> Stedin, the Netherlands

Project details
> Duration: 2005-ongoing