Modelling the degradation of condition indices

To ensure that the electricity distribution network achieves satisfactory l evels of reliability and safety it is necessary to have well-founded and ju stifiable asset management policies in place. For many items of electricity distribution equipment, failures have been rare and inferences about futur e lifetimes are difficult to make. The paper argues that in such situations , importance should be given to obtaining condition information to aid asse t management. A key requirement in using such data is the capability to mod el changes in an item's condition and the Markov model is proposed as being particularly suitable. The application of the Markov model to a collection of oil condition data, recorded during maintenance activity, is explained. The impact of such a model in making asset management decisions is then il lustrated.