GB1427980A - Voltage transformer - Google Patents

Abstract

1427980 Transformers STROMBERG AB Oy 27 March 1973 [7 April 1972] 14779/73 Heading H1T A voltage transformer comprises a main insulator 1 of concentric metal foil cylinders separated by insulation, within a hollow insulator 7, at least one first winding 5 outside insulator 1 and at least one second winding 4 inside insulator 1, these being enclosed within a magnetic core structure 2<SP>11</SP>2<SP>1</SP>2<SP>111</SP>, 3, 6, of which parts 3 and 6 are tubular. The insulator 1 provides an air gap but the sections 2<SP>11</SP> and 6 are magnetically joined. The lower and upper ends of the part 6 are connected to the low voltage (earth) and high voltage ends of the winding 5 respectively. The insulating cylinders 12 of insulator 1 are of equal thickness and length and longer than the foil cylinders 11 which are of equal length and overlap but are axially displaced in equal steps, H/m, the length H of the stepped section of insulator 1 being at least that which withstands the voltage and m being the number of insulating cylinders. The stepped sections of insulator 1 are axially outside the core or opposite the first winding. Filler insulation 13 is provided so that the primary winding is wound on a cylindrical surface. The primary winding may comprise several coils above each other in an axial direction. In other embodiments the primary and secondary windings 5 and 4 may be interchanged and the tube 6 may be inside insulator 1.