回転機固定子巻線の繰返し曲げ荷重下における変形ならびに破壊挙動

抄録

This paper presents the deformation and fracture behaviors of the stator windings under repeated bending loads. In this investigation, two different kinds of stator windings, which were impregnated with epoxy and polyester resins, were examined. The stiffness of the stator windings was measured after a certain number of repeated bending loads was applied to the stator windings. At the same time, the tanδ characteristic was also measured and then the mechanical damage produced in the stator windings was discussed. The breakdown voltage was also measured in the last stage of each test and the fracture of the insulation was discussed. The results obtained are as follows.
(1) When the repeated bending loads beyond a certain strain level were applied, a remarkable reduction was found in the stiffness of the stator windings with the increase of number of repeated bending loads. The stiffness at which the breakdown voltage decreased to the rated voltage was reduced to 60∼75% of the initial stiffness.
(2) Below this cyclic strain level, the reductions in stiffness and breakdown voltage were comparatively small and no fatigue damage was found in the stator windings.
(3) The maximum strain amplitude which could be applied to the stator windings without fatigue damage up to 10⁷ cycles was about 30∼42% of the ultimate tensile strain.