## 3 New Concept for Assessing the Technical Condition of HV Switching Bay Devices
### Data Preprocessing: Methodology for Classifying DIDs in HV Switching Bay Devices  
Section 2 discusses the maintenance tasks (SI, GC, M, T, and UI, as shown in Figure 2) for devices in the HV SB (CB, D, and IT) aimed at detecting possible DIDs. All maintenance activities, including the identification of DIDs, are recorded in the IBM Maximo IS. Over the years, an extensive set of DIDs has been compiled in TSO ELES, which are of such a nature that the device could continue to operate without failure or faults. A detailed analysis was conducted of these DIDs. Based on the research carried out by the authors of [8], a suitable and meaningful classification of DIDs into groups was developed for each element of the HV SB (CB, D, and IT). A detected DID can affect the potential occurrence of a future failure or fault in the device's primary circuit parts (electrical subsystem--E), mechanical parts (mechanical subsystem--M), the dielectric properties of the devices (insulation subsystem--I), and the auxiliary parts of the devices (auxiliary subsystem--A). Based on detailed analyses, the general form of the defect and internal damage of the HV SB device can be expressed as \(DID_{el,ij,}^{k}\), where \(el\in\{\)CB, D, IT\(\}\), \(i,j\in\mathbb{N}\), and \(k\in\{\)E, M, I, A\(\}\). The first group of DIDs pertains to deficiencies or internal defects occurring in parts of the primary circuit, which could result in the failure or internal fault of the primary circuit (\(k=\) E). These include poor connections relative to HV connections and primary contacts. The second group of DIDs relates to deficiencies or internal defects in the mechanics of the drives, which could result in mechanical failure or mechanical faults (\(k=\) M). These include internal defects associated with the actuating system, drive, and drive/control box. This group also includes the mechanical defects of post-insulators. The third group of DIDs pertains to defects in the dielectric properties of the insulating medium (\(k=\) I). This group includes primarily insulator damage and the deteriorated dielectric properties of the insulating medium (SF\({}_{6}\) or oil). The fourth group of DIDs relates to deficiencies in the auxiliary systems of the devices (\(k=\) A). These include grounding systems, supporting structures, and devices related to control and signaling. Each deficiency or internal defect in the database is described briefly using an indicator. Based on the analysis, tasks are assigned for each DID, specifying the type of DID discovered (SI, GC, M, and T) and identifying a probable initial cause (IC) for its occurrence. Remedial action is also determined to eliminate the DID. The most critical aspect of the DID classification is the rate of deficiency or internal defect (RDID). Each DID is categorized into one of three levels, \(RDID_{el,i,j}^{k}\in\{1,2,3\}\). Minor deficiencies are assigned an \(RDID\) level of 1. Significant deficiencies and minor internal defects are assigned an \(RDID\) level of 2. Major internal defects are assigned an \(RDID\) level of 3. The levels for each individual \(DID_{el,ij}^{k}\) are defined based on the Maintenance Code rules for the maximum period of time for remedial action and the analyses of DIDs. The maximum deadline for eliminating deficiencies or internal defects is closely related to their assigned level. For \(RDID=1\), the maximum agreed deadline for dispatch (DFD) is 1 year, expressed as \(DFD\) (\(RDID=1\)) = 1 year. For \(RDID=2\), the maximum agreed deadline for dispatch is 3 months, expressed as \(DFD\) (\(RDID=2\)) = 3 months. For \(RDID=3\), the maximum agreed deadline for dispatch is 1 week, often requiring immediate action, and it is expressed as \(DFD\) (\(RDID=3\)) = 1 week. This comprehensive methodological approach for classifying deficiencies and internal defects facilitates the creation of a database of the deficiencies and internal defects within a TSO. It enables the statistical analysis of DID occurrences.