Analisi asset cabina secondaria Confronto vita regolatoria e vita tecnica

This paper addresses the age of assets installed in the MV/LV secondary substations of Unareti S.p.A., a Distribution System Operator in the Milan area. It was developed as part of an internship at the Asset Performance department of the A2A Group. In the management of electricity distribution networks, tariff regulation defines a regulatory life for each type of asset, i.e., the amortization period recognized in the tariff by the Regulatory Authority for Energy, Networks and the Environment (ARERA). However, the actual useful life of assets can deviate significantly from this economic-accounting parameter, in either direction. This divergence, if not adequately analyzed and managed, can result in suboptimal investment decisions, latent risks of unplanned failure, and inefficiencies in planning the renewal of the installed asset base. This thesis aims to quantify and interpret this gap through an analysis of data extracted from company management systems for three asset categories present in secondary substations: the MV/LV distribution transformer, the medium-voltage disconnector (both motorized and non-motorized), and batteries. For each type, the distribution of the age of the operating fleet, the average age at decommissioning, the history of maintenance work orders, and the correlation between age and frequency of corrective interventions were analyzed. The results were interpreted considering the physical degradation mechanisms specific to each asset. The results show that the three assets exhibit structurally different aging profiles, each governed by distinct dynamics: the robustness of transformers, which, given the absence of moving parts, achieve useful lives exceeding the regulatory threshold with a predominantly corrective maintenance strategy; the operational duty cycle and switching frequency of the disconnectors, with significant differences between the motorized and non-motorized variants; and accelerated electrochemical aging for VRLA batteries under the thermal conditions of underground substations in Milan. In all three cases, the ARERA regulatory life appears to be a parameter that is partially misaligned with the actual observed useful life, with concrete implications for the optimal maintenance strategies to adopt. This work provides a structured knowledge base for guiding asset management policies toward more informed approaches that integrate regulatory parameters with assessments of the actual condition of assets, in line with the principles of the ISO 55001 standard and condition-based maintenance strategies.