Depth of Burial of Subsea Power Cables
Depth 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.

To reduce the risk of cable damage and to conform with legal requirements, cable operators today are obliged to verify the Depth of Burial (DoB) of submarine cables in regular intervals, e.g. by carrying out costly magnetometer measurements or submarine robot inspections.
However, natural events such as sediment mobility or seismic activity can change the DoB within a short period of time, making continuous DoB monitoring the most reliable approach to risk mitigation.

Depth of Burial State Monitoring (DoBS)

AP Sensing’s DoBS module is a reliable solution to enable predictive maintenance and regular monitoring of changes in the Depth of Burial of a submarine power cable. The trace of the burial depth state is a function of the observed dynamic temperature variations depending on the characteristics of the marine environment as well as the correlation with the cable load. This unique solution doesn’t require the precise and spatially resolved knowledge of additional ambient conditions and soil parameters to prepare the computational model. It also ensures that minor deviations in the input data do not lead to dramatic inaccuracies in the calculation of the burial depth that are observed with other solutions. For offshore power cables, which usually have integrated optical fibers, AP Sensing’s DoBS solution only requires the installation of a DTS unit at an onshore or offshore location to enable an accurate determination of the burial depth state.

DoBS Features

  • DoBS monitoring along the entire power cable with configurable pre-alarms and alarms
  • Reliable detection of changes in the burial depth
  • Accurate location of washed-out cable sections and free spans
  • Thresholds are configurable for alarming and pre-alarming

Benefits of DoBS

  • In contrast to full modelling approaches, AP Sensing’s unique solution works without the need to know the exact environmental conditions as input parameters   (e.g., water temperature, soil type, current effects) and therefore allows more reliable results and a faster commissioning.
  • Unlike model-based solutions that calculate incorrect DoB values even with very small deviations in environmental parameters, AP Sensing's DoBS solution computes stabile results under such conditions.

Output Data

  • DoBS – Depth of Burial State (status trace)
  • Pre-alarms, alarms, faults and system status
  • Via industry protocols, such as Modbus TCP, IEC 60870-5-104, IEC 61850 and others