Abstract
This paper analyzes the problem of occurrence and development of fatigue processes in the insulation of traction motors of autonomous locomotives. Factors causing destruction (cracking, delamination, occurrence of voids) of insulation in operation have been studied in the course of the research. Three characteristic stress cycles (reversible, repetitive, random) were described to make fatigue failure predictions. Outcomes of investigations of temperature conditions of windings of electric machines of diesel locomotives show that during operation the insulation experiences variable thermomechanical stresses. Received data can be recommended to take into account during the creation of new electric machines for diesel locomotives, as well as during the operation and resource recovery of already existing ones.