Coil winding assembly for instrument transformer - comprising sub-assemblies of unit turns arranged to give closely spaced tappings

摘要

The object of the coil assembly is to give closely spaced tapping points without requiring unused windings at any point. The complete coil is made up using a basic subassembly or subcoil (c) with a fixed number of turns. These subcoils are connected together to form other winding parts; a main coil (a) consisting of z subcoils in series, where Z=1, 2, 3..., and part coils (b) of m subcoils, with M=O, 1, 2,.. The complete winding comprises one subcoil (c) on one side of the main coil (a), and several part coils (b) on the other side. The sum of the subcoils in the part coils is always one less than the number of subcoils in the main coil. Tapping points are provided at each sub, part and main coil connection. By careful choice of turns on the subcoil, the tapping points can progress in very small discrete steps. Arrangements with two separate coil assemblies on this principle can be interconnected with jumpers to get the required tappings.