Investigation on different maintenance rules in the case of load variation

With the assumption that the load variance of each apparatus in the reality is of the same value, the former works of Life-Cycle-Cost assessment based on actual data of accelerating degradation neglect the influence of different load to the aging process of apparatus. Nevertheless, the actual operation time can not reflect the real aging time of the insulation system. This paper assumes that in the whole apparatus system the probability density of the power apparatus with load rate factor r follows uniform or normal distribution; therefore, the deviation between the real aging value and the actual operation time is taken into consideration to modify the evaluation of different maintenance strategies. Furthermore, the relation between the real aging time and the actual operation time of power cable can be calculated based on real data. Evaluation of the life-cycle-cost on the basis of actual data of accelerating degradation is put forward to investigate the economic feasibility of different maintenance rules in this paper. The calculation results show that the economic merits of diagnosis rules are influenced by the dispersion of load rate distribution. Frequent diagnosis may not always benefit the economic feasibility of maintenance rules. The maintenance rule without diagnosis may generally save a lot of total cost than those with diagnosis, at the circumstance that the deviation of real aging time distribution is of large value, which may attributed to the uncertainty of failure rate.