Analogue investigation of water cooling of e.h.v. cables

The paper describes the use of an electrical-resistance analogue to investigate the factors governing the current rating of water-cooled underground transmission cables. The effects of cooling-water temperature, soil thermal resistivity, cable size and spacing, joints and possible alternative dielectric materials on circuit rating are examined and discussed. The results indicate that water cooling can increase the rating of a cable by between 50% and 150%, depending on the method of cooling adopted. The circuit rating will, however, depend on the efficiency of cooling at the joints.