GB798870A - Improvements in and relating to tap changing switches provided with bridging resistances for regulating transformers - Google Patents

Abstract

798,870. Transformers. SMIT & CO.'S TRANSFORMATORENFABRIEK N.V., W. Feb. 11, 1955 [Feb. 22, 1954], No. 4206/55. Class 38 (2). [Also in Group XXXVII] An on load tap changing switch for changing the connection of line 59 to taps 23-28 of transformer 22 comprises in concentric arrangement, fixed contacts 29-34 connected to the taps, a first rotatable cylinder carrying two groups of contacts 38-45 and 46-53 respectively to taps on resistors 55, 56, contacts 38, 46 being connected to selector contacts 36, 37; and an inner rotatable cylinder carrying contacts 54. To change the connection from tap 23 to tap 24 the cylinders are rotated in the directions shown by the arrows. Connection between contacts 54 and 36 is first broken, line 59 remaining connected to tapping 23 through 54, 46, 37, 29 and through 54, 45, resistance 55, 36, 29. Contact 36 then leaves 29, and line 59 is connected to tapping 23 only through 54, 47, resistance 56, 37 and 29. On further rotation contact 36 engages 30, when the resistances between 54 and 36 and between 54 and 37 have been respectively reduced and increased by about one-third. Thus the rotation decreases the amount of resistance 55 and increases the amount of resistance 56 connected across tappings 23, 24. Finally line 59 is directly connected to tapping 24 through contacts 54 and 36, 37 which engage segment 30. The arc lengths of 29-34, 38 and 46 may be altered so that the selector switch operates under no-load. In modifications the contacts may be divided into two coaxial, axially displaced groups, Fig. 3 (not shown), or the change-over switch contacts may be divided into two diametrically opposite pairs and the resistors 55, 56 with associated contacts may be arranged on opposite halves of the periphery, Fig. 4 (not shown).