Depth of Burial of Subsea Power CablesDepth of Burial of Subsea Power Cables

Depth of Burial of Subsea Power Cables

Submarine power cables operate in a dynamic seabed environment where cables can become exposed and prone to mechanical damage or heavily buried, leading to insufficient heat dissipation. Furthermore, legislation in some countries demands annual Depth of Burial (DoB) inspection of new cables within the first five years after installation in order to limit the heating of the seabed. To reduce the risk of cable damage and to conform with legal requirements, cable operators today are obliged to monitor the DoB of submarine cables in regular intervals, e.g. by carrying out costly magnetometer measurements or submarine robot inspections. Natural events such as sediment mobility or seismic activity can change the DoB within a short time.

 

Depth of Burial Monitoring via DTS

Distributed Temperature Sensing (DTS) enables monitoring of the dynamic temperature variation in a power cable due to the applied load current. For offshore power cables, which usually have integrated optical fibers, this only requires installation of a DTS unit at an onshore or offshore location. The observed dynamic temperature variation will depend on the characteristics of the marine environment.

For a large range of sediments, the Depth of Burial module enables the determination of the DoB of a power cable by combining DTS data with a physical model of the cable and the seabed environment. To enable predictive maintenance and monitor changes in the DoB of a submarine power cable, the DoB module can be run at regular intervals.