## 1 Introduction  
World economy and energy production trends also affect the power grid, plant management and maintenance techniques. Those trends greatly contribute to mergers of companies with different infrastructure, strategies and IT support. Such companies own plants of various conditions, some well past their prime, but seldom brand new. In an environment where the price of production is subject to market competition on a global level, it is necessary to find an optimum or a compromise between investments in the development, reconstruction and maintenance of facilities, on the one hand, and the market price of products or services, on the other hand. When choosing the appropriate maintenance method, the documentation on the plant's behavior, the database or knowledge base in the types of faults, their frequency, as well as the service life of each part or the entire plant, proved to be particularly useful. A digitalized knowledge base with an appropriate information system and the necessary tools for analyzing existing data enables simpler decision-making based on objective information and with less of a labor force needed. For this purpose, special software packages that enable simpler and more efficient plant management are being developed. By connecting such tools with the plant management system, it is possible to document the measures taken and later, analyze the fidelity of the decisions made followed by the accompanying consequences on the plant or production process [1; 2; 3]. Efficient plant maintenance leads to a reduction in production costs and the conservation of resources. Technical maintenance is necessary for ensuring the system's operating efficiency and attaining the desired performance. Since the operation and maintenance costs of technical equipment and systems might range from 15 to 30% of the lifespan cost, they are not eligible. As a result, managing and reducing maintenance costs has become increasingly important to academics, stakeholders and operators. Ordinarily, the increase in efficiency can be achieved by continuous collection and classification of data for observed object and its components to increase reliability and reduce mandatory maintenance measures, implementing strategies for better organization of operation and maintenance, transparency of operations, displaying all costs and evaluation of the justification of individual investments. The successful implementation of the above requires up-to-date knowledge of the technical and economic conditions of plant operation, access to and the analysis of a large amount of information and collected data; therefore, the existence of an efficient information system based on modern hardware and software solutions is necessary. The process of exploitation of the technical system is disrupted by the degradation of its performance. To maintain the level of production, negative changes in the technical system must be prevented by certain countermeasures in order to restore the original operability of the system. The measures taken in this case are considered maintenance. The definition of maintenance as a technological procedure can be defined as the measures necessary for the preservation and restoration of the nominal condition of the object or procedures related to the determination and assessment of the current condition of technical objects and systems, which includes prevention, diagnosis, condition analysis and repair. Norm DIN 31 051 addresses maintenance activities such as servicing, inspection and repair [4]. The general issue of the maintenance strategy is opting for maintenance before or after the fault occurrence. Maintenance after the fault occurrence (Failure maintenance, Breakdown maintenance) operates after a fault and depends on its type and severity. With this type of maintenance, there are no preventive actions. Malfunctions or errors usually lead to a stoppage of the entire system and/or an interruption in its operation.