GB395173A - Switching arrangement for step transformers for large currents - Google Patents

Abstract

395,173. Regulating transformers. SIEMENS-SCHUCKERTWERKE AKT. GES., Siemensstadt, Berlin. Aug. 6, 1932, No. 22155. Convention date, Aug. 7, 1931. [Class 38 (ii).] A switching arrangement for step transformers for large currents, capable of being regulated under load, comprises tap selectors 2a, 2b connected to primary windings E1, E2 of auxiliary transformers the secondary windings S1, S2 of which can be short-circuited directly or through resistances 4a, 4b, or open-circuited, by rotation of a switch 3. In the position shown in Fig. 2 both secondary windings are short-circuited, the resistances of the primary windings are negligible, and the load current, taken from a tapping between the primary windings E1, E2 is divided equally on the selectors 2a, 2b. On rotating the switch 3 through 90‹ in a clockwise direction the winding S2 is opened, and the resistance of E2 becomes very high compared with that of E1, so that the selector 2b becomes practically dead and can be advanced to a new position. In the next position of the switch 3 both secondary windings are short-circuited through the resistances 4a, 4b, which may be so dimensioned as to produce a voltage drop across the auxiliary transformers equal to the voltage of one step of the main transformer winding 1. In a modification, Fig. 3, the resistances are in the form of choking coils wound on a common core 4. The auxiliary transformers may be wound as autotransformers.