| 摘要 |
PURPOSE:To improve mechanical strength by providing the upper surface of a mold coil with a strengthening layer consisting of a fiber base material impregnated with a resin while making a mold material of th side of a mold coil have a predetermined thickness. CONSTITUTION:Around a coil body 3 wound in the shape of a japanese character < an earthed insulating layer 4 is provided to be covered with a mold material layer 5 such as a resin concrete or resin mortar. Then the upper surface of said mold material layer 5 is provided with a stregnthening layer 6 consisting of a strengthening fibrous base material 6, wherein, for instance, a glas cloth, glass mat or glass unwoven cloth is impregnated with resins. And the thickness t2 of the mold material layer 5 on the side of the mold coil 2 is made so as to be more than 1.0 time and less than 3.0 times of that t1 of the mold material layer 5 on the upper surface. Thereby the destruction caused by the electro-magnetic force of the mold coil 2 is made to occur through a long path in the mold material layer 5 thus to remarkably improve mechanical strength. |
