Twentieth century handbook for steam engineers and electricians, with questions and answers; a practical nontechnical treatise .. (1916)
Swingle, Calvin F. (Calvin Franklin), b. 1846 · Chicago, F.J. Drake & company · leaf 1081
called Drum cores when the central holeis just large enough for the shaft and the insulation aroundit (Fig. 439) ; and are named Ring cores when the inter-nal diameter of the ring is much larger than the shaft.(Fig. 441.) The armature in Fig. 442 has a ring core, butthe end plates being in… … Fig. 441 SIMPLE GRAMME RING WINDING pasted on. The rust, varnish and paper are all insulatorsand when the punchings are assembled in a core, preventEddy currents from flowing from one end of the armatureto the other and heating it. These cores are sometimes smooth, but more frequentlyare slotted…
