Principles of forecasting and mathematical modeling of the change of resistance of insulation systems in electric motors of printing machines and complexes

The creation of mathematical models adequate to the probable processes of functioning of the investigated insulation system is one of the main tasks when studying the reliability of electrical insulation systems and at developing the methods for predicting the reliability. Mathematical model reflects only the degree of our knowledge of the existing mechanism of system functioning, so it is only some approximation to the investigated process. The process of developing a mathematical model lies not only in theoretical development of any hypotheses about the actual behavior of the object, but in a constant verification of the conformity of adopted hypothesis and the availability of statistical data obtained by conducting experiments. The paper proposes a mathematical model to determine the distribution of the breakdown voltage and the reliability function of the insulation system of electrical machines printing systems. Operating experience has shown that the insulation performance of the product largely depends on physical-mechanical properties of polymeric materials. Moreover, if electrical loads operate on electrical insulation only within the period of performance of the product, mechanical loads and, firstly, internal voltage act on the insulation both in the period of operation and disconnecting from the network. They occur in polymeric materials during the process of product manufacturing and act in it throughout its existence, including the periods of transportation, storage and installation. Underestimation of the importance of internal stresses and insufficient consideration of mechanical loads on polymer materials in constructions lead to deterioration of operational properties of the insulation, reducing its reliability. Wear resistant properties are measured by short-term tensile strength and are characterized by time-temperature dependence. Destruction of polymers is a process developing in time. It is associated with rupture of the chain of macromolecules by chemical bonds. Mechanical loads reduce the service life of polymeric materials, therefore, unloading of polymers in the structures, rational design of electrical insulation systems are of great importance in improving the quality of the insulation. The analysis of changes in insulation resistance depending on the ambient conditions and the load of the drive of printing machines and complexes is made