WATERTREE – Predicting failure of dynamic subsea cables by insulation breakdown

The offshore energy sector is moving towards installation of floating offshore wind turbines and farms with tidal and wave energy devices. A challenge for these installations is the cable which hangs from the base of the installations to the seabed or a hub. This arrangement exposes the cable to the dynamics of the marine environment it is installed in creating concern for failure of these dynamic cables. One failure mechanism of subsea cables is the degradation of the insulation layers by so-called “water treeing” induced by strong electric fields in the defects in the material caused by mechanical stresses. This project develops simulation models and a methodology that enable growth analysis of water trees in dynamic subsea cables due to mechanical and electrical loadings. It allows for prediction of the time it takes for a water tree to grow to a size which causes cable failure. The ability to predict when a dynamic cable is at risk of failure is crucial for planning of maintenance.

Partner organizations

• NKT Cables AB (Private, Sweden)
• RISE Research Institutes of Sweden (Research Institute, Sweden)