Due to the motion of the armature, a local concentration of current and Joule heating occurs at the rail-armature interface and causes significant erosion and damage.

• 同时由于电枢运动，电流趋向导体表面流动并在电枢尾部与轨道接触面上趋于集中，使电枢尾部焦耳热剧增导致出现高温烧蚀。