Cable rating methods applied to a real-time cable system monitor

The authors outline how the National Grid Company (NGC) has a national scheme to provide cable system monitors (CSMs) installed in its area control centres. The CSMs provide online continuous and overload thermal ratings of cables based on system measurements and real-time thermal modelling, and enable the control engineers to assess the present security of the system and plan the operation of the system for the next day or possibly the following week. The CSM also holds archive data for retrieval and subsequent analysis