Optimization Of Metallic Shields For Extruded Dielectric Cables Under Fault Conditions

Full scale laboratory tests were conducted to determine the maximum temperatures which round wire and flat strap metallic shields can withstand without damage under fault conditions. A computer model was developed to calculate the shield temperature rise with high accuracy for given cable designs, short-circuit currents and sequences. A simplified short-circuit test procedure was developed to facilitate evaluation of new cable designs. This procedure utilizes the computer program and a newly introduced concept of short-circuit equivalence factor which provides a tool for equating laboratory and field conditions. The results of this project, sponsored by EPRI, enable the cable engineer to optimize metallic shield designs with a substantial reduction of initial and operating costs.