Cable monitoring
Online condition monitoring for power cables using Distributed Electrical Sensing (DES).
Megger products are used around the world for cable commissioning, condition monitoring and fault location. Between these ‘static’ monitoring events, power cables are subject to years of operational stresses and cyclical loads that can lead to sudden failure. DES technology is a cost-effective and scalable way to monitor power cables throughout their operating lives to avoid this failure, safely optimise capacity, and improve scheduled maintenance costs for asset owners.
Our solution
Distributed Electrical Sensing (DES) technology is ideally suited to cable condition monitoring as it streams continuous and synchronous measurements in industry-standard formats from every cable joint and termination over long distances. By monitoring cable sheath currents using DES, it is possible to improve the accuracy of circuit models while monitoring for early signs of sheath and screen damage, overheating, electrical trees, breakdowns, and flashovers. The addition of phase voltage and phase current sensing enables the monitoring of electrical transients and harmonic content. Transients from switching sources, capacitor banks, and inductive loads commonly associated with power electronics can stress circuits and, over time, cause damage. Transients can slowly degrade insulation, eventually leading to localised overheating and short circuit currents. Synaptec’s cable condition monitoring technology provides utilities with a unique and comprehensive set of cable asset insights, allowing more failure modes to be monitored for progression and providing actionable insights at significantly earlier stages of degradation.
Where does DES add value ?
Around 69% of high voltage (HV) cable failures occur in joints and terminations that are invisible to conventional monitoring techniques like distributed temperature sensing (DTS) or distributed acoustic sensing (DAS). Synaptec DES sensors are totally passive, with no requirement for control power, data networks, or expensive civil works. This makes it feasible to instrument any number of remote or inaccessible locations, providing early warning of more cable failure types than with conventional optical monitoring techniques. This dramatically improves availability and safety, while reducing outage costs and optimising scheduled maintenance over the life of the network.
Learn more about DES technology, and its various applications
Distributed Electrical Sensing
Monitoring in power grids
Monitoring in offshore wind
Mixed circuit protection
Transmission line security
Overhead line monitoring
FAQs
Maximum distance for a single sensor is 60 km. The maximum distance is limited by the dynamic range of the Interrogator, so adding additional sensors and/or losses in the fibre network will reduce the available distance (as is the case for any FBG-based measurement system).
Voltage sensors meet IEC class 3P. Current sensors meet IEC class 5P. In general, electrical measurement accuracy is ‘within 1%’.
As a ‘rule of thumb’, each DES Interrogator can handle up to 30 single-phase electrical sensors (10 three-phase sensors) on one fibre but typically systems achieve less than this (sensor numbers in the 20s) once actual project specifications (e.g. distance, losses and measurement ranges) are known. The primary limiting factor is the optical bandwidth required for each sensor, which is dependent on the operating temperature range and the measurement range it must measure (e.g., maximum voltage/current). mDES and DMS Interrogators are alternatives configured for lower fidelity electrical measurements (mDES) or only mechanical measurements (DMS) but can handle multiple sensor fibre arrays.
Additional resources
Take a deeper dive with some customer projects
Case study : Vattenfall
Cable condition monitoring to provide earlier warning of more failure modes
Case study : Red Eléctrica
Cable condition monitoring of underground power cable joints to provide earlier warning of more cable failure modes when compared to conventional monitoring.
Case study : SSEN
Affordable, resilient protection of multi-ended transmission circuits using passive, distributed current sensors.
