GB986106A - Improvements in or relating to transformers - Google Patents

Abstract

986,106. Transformers. V. & E. FRIEDLAND Ltd., J. DOGGART, and D. F. BARTON. June 14, 1961 [July 19, 1960], No. 25177/60. Heading H1T. A transformer has terminals fixed on the bobbin or bobbins, and the terminals project freely through apertures in a cover, which is fitted over the assembly, so as to be accessible from the exterior. In a bell transformer, two bobbins carrying the primary and secondary windings 14, 15, Fig. 1, are carried respectively by limbs of a core comprising a stack of U- shaped laminations, the open ends of the laminations being placed at opposite ends of the stack alternately. Each bobbin has, at each end, an integral projection on which a terminal 22 is secured. The ends of the windings are soldered to tags mechanically attached to these terminals. A tapping on the secondary winding 15 is connected to a similar terminal 33 on an insulating plate 31 mounted on the bobbin between its ends. A polypropylene insulator plate 39, which separates the primary and secondary coils 14 and 15, has end flanges 40 engaging a groove 38, Fig. 2, formed by rebates in adjacent edges of cheek plates 18. This assembly is enclosed by a plastic casing comprising a base plate 46, Fig. 7, and an interfitting cover 45 through which pass air flow passages between fins 66, extending from the cover top to projections 67 which locate the core ends. The ends of the core are clamped between projections 67 and abutments 50 on the baseplate. Detachable cover plates 55, Fig. 5, cover the terminals which project through holes 61, Fig. 7, in the casing side-wall 56, Fig. 5, and are flanked by side plates 62 and blocks 59 to which the cover 55 is secured. The casing also has a sloping lead wall 57 adjacent to each set of holes. The use of alternately placed U-shaped laminations for the core reduces the cross-sectional area of the yokes so that they become saturated under shortcircuit conditions and prevent damage to the windings.