Mechanical Effects of Thermally Induced Bending on 550-kV Pipe-Type Cable

Thermo-mechanical bending tests were performed at Waltz Mill to assess the potential problem of structural damage to 550-kV cable caused by flexure within the line pipe. During the tests, realistic bending was accomplished by creating thermal expansion with conductor heating. Testing was performed in a manner which represents the most severe situation for a long, straight run of cable. To duplicate severe mechanical conditions, the cable system was subjected to 327 thermal cycles to a conductor temperature of 1300C. It should also be noted that this cable had previously been exposed to numerous load cycles during other testing at Waltz Mill 1,2, and 130°C is higher than the emergency operating temperature. This paper documents various physical parameters such as forces, movement, and strain which develop during thermal expansion.