METHOD FOR TESTING WATER-TREE RESISTANCE OF CABLE INSULATOR

摘要

PURPOSE:To provide a method for testing water-tree resistance whereby generation and development of water-tree on a cable insulator can directly be observed, a required high voltage can surely be applied to the cable insulator sample and highly reliable evaluation of the water-tree resistance can be done. CONSTITUTION:A ring-shaped sample 6 is sandwiched between two transparent insulating plates 7 from both of cut planes and a watertight hollow portion 9 is formed at the center of the sample 6. The hollow portion 9 is filled with water and the end of a metallic lead wire 12 pulled out of a high voltage transformer 11 is inserted into the water. Thereafter, the above components are submerged in a water tank 13 and the water in the hollow portion 9 and the water in the water tank 13 are utilized as electrodes and a high voltage transformer 12 applies a predetermined voltage between the inner and outer peripheral faces of the sample 6. Because water-tree is generated and developed on the sample 6 by the application of the voltage according to the characteristics of the sample, the development of the water tree is observed through the transparent insulating plates 7.