GB826138A - Improvements in or relating to armature coils for dynamo electric machines - Google Patents

Abstract

826,138. Commutator windings for dynamoelectric machines. FLETCHER, G. H. Jan. 29, 1957 [Feb. 16, 1956], No. 4902/56. Class 35. In an armature winding similar to that described in Specification 792,428, in which the slot conductors occupy the width of the slot and are divided into several electrically-connected sections or strands, one of which, at each turn, is extended beyond the rest to provide commutator connections L at the rear end of the coils, the two sides of each coil between adjacent segments are kept equally spaced above and below the horizontal centre-line of the slots to equalize their reactances, by the transposition of one conductor. In the conventional arrangement in which the coil connection and commutator connections are at the same end, the concentric arrangement of the coil conductors with respect to slot position means that both sides of each coil are equally displaced from the central level of the slot, so that, for instance, a deep conductor is connected in series with a correspondingly shallow one, and the coils thus all have the same total inductance. When the commutator connections are made at the rear end of the coils, this symmetry is upset. It is restored, according to the invention, by transposing one conductor to which the next coil is connected from its concentric position. As shown, the conductor 10 connected to the start S of the coil is transposed from its concentric position 6 just below the central level of the slot, to the bottom of the slot. The commutator coils are now 5 and 6; 4 and 7; 3 and 8; 2 and 9; and 1 and 10 of the next slot through the coil-connection F. Similarly conductor 10 is connected to 1 of the next slot in the other direction at S.