## 3 New Concept for Assessing the Technical Condition of HV Switching Bay Devices  
The groundwork for the new concept is proposed by the authors of [23]. The procedure for determining the technical condition of devices in a 400 kV switchyard is discussed by the authors of [23]. The device's condition is defined as a state indicator. The technical condition of the device, denoted as \(c\), is calculated using the internal script in MS Access, which is connected to the technical database in IBM Maximo IS. This database contains a set of criteria with corresponding weighting factors \(u\) (ranging from 1 to 10) and evaluation factors \(o\) (ranging from 1, indicating good, to 10, indicating bad). The weighting factor \(u_{j}\) is determined based on the role and importance of criterion \(j\) for the type of device installed in the transmission system. The evaluation factors \(o_{j}\) for each criterion are determined by the engineer responsible for supervising the individual transmission substation. The condition of the device \(c\) is calculated using (1), which represents the sum of the normalized weighting units of the criteria. \[c=\frac{\sum\limits_{j=1}^{n}\left(u_{j}\cdot o_{j}\right)}{\sum\limits_{j=1} ^{n}\left(u_{j}\cdot o_{j,\max}\right)}\cdot 100\%. \tag{1}\]  
Equation (1) provides an overview of the condition of devices for each HV device in the substation. A lower value of \(c\) indicates a better condition of the device, while a higher value of \(c\) indicates a worse condition. The total value of condition \(c\) is normalized on a scale from 1 (good) to 100 (bad). A manual grade input is required to assess the device's technical condition, making the evaluation inherently subjective. The criteria are developed most thoroughly for calculating the technical condition of CBs. The model in Equation (1) was developed for the RCM diagram, where a smaller creation percent means a better partial condition, and vice versa. The better partial condition of the criteria is reflected in lower grades, and vice versa. Based on Equation (1), which represents the existing concept, a new approach for calculating the technical condition of devices in an HV SB is introduced using (2). This new concept primarily targets the key components in an HV SB, such as CBs, Ds, and ITs. The maintenance tasks used to monitor and evaluate the condition of these devices are reviewed in Section 2. For each device, these tasks determine whether the condition is satisfactory (i.e., no deficiencies or internal defects (DIDs) are detected) or deficient (DIDs are detected). All the maintenance activities described in Section 2 are integrated into the new concept for assessing a device's technical condition, as outlined using (2). \[c=\left(\prod\limits_{i=-1}^{-N}GCR_{i}\right)\cdot\left(\frac{\sum\limits_{j= 1}^{M}GCR_{j}\cdot w_{j}}{\sum\limits_{j=1}^{M}GCR_{j,MAX}\cdot w_{j}}+1\right). \tag{2}\]  
The new concept for calculating device condition (2) is designed such that a higher value indicates a better overall condition, and vice versa. The value of assessment is the same as for the health index. In this manner, a better particular criterion grade reflects a better partial condition for the partial criterion \(CR_{j}\). This is the exact opposite of the existing concept (1), where a lower value signifies a better technical condition. The inversion in the new approach stems from the mathematical use of a limit sequence involving powers of 1/2. This sequence is used to reflect maintenance prioritization, where lower numerical values correspond to a poorer technical condition and, consequently, a higher maintenance priority. More details are provided later in this manuscript. In Equation (2), the first term (in parentheses) represents the multiplicative criteria, with a maximum value of 0.5, while the second term (also in parentheses) represents the additive criteria, with a maximum value of 2. In Equation (2), the counter \(i\) is assumed to be a negative integer \(i=-1\), \(-2\),..., \(-N\).