The overall aim of the project is to develop a methodology for the evaluation the status of the operating power cables, and the estimation of the life time of these cables. The objectives of the work are: 1. Establish the corresponding relationship between the aging state of cable insulation and the characteristics of space charge under different operating conditions. 2. Obtain the aging characteristics and life of the space charge of the aging cable samples, and establish and verify the evaluation model of the cable aging based on the space charge characteristics. 3. Establish the relationship between the important parameters of space charge characteristics and the physical theory of on-line monitoring parameters. 4. Establish the cable state evaluation model based on space charge characteristics and on-line monitoring parameters.