Advantages of HV cable transmission links by using real time thermal rating (RTTR) and water monitoring

In modern high-voltage cable systems, temperature overloads or water ingress are often limitation parameters for its lifetime. However, two highly sophisticated monitoring techniques are available to control these parameters. A system based on distributed temperature and load monitoring to enable cables to be more effectively loaded without exceeding thermal limits and a system for monitoring the dry condition of the insulation and alarming the ingress of water into the cable in the event of external sheath damage. Both systems are already introduced into commercial plants and have shown their excellent performance. The measuring principles, hardware and software concepts of these systems are presented as well as different cable designs, sensors and cable laying arrangements. Furthermore, the advantages and yet available experiences of these systems are evaluated and discussed. General aspects of monitoring and individual steps helpful to users for checking if monitoring offers advantages in their application complements this contribution.