GB506015A - Improvements in or relating to moving contact electric current converters - Google Patents

Abstract

506,015. Converting. SIEMENS SCHUCKERTWERKE AKT.-GES. Nov. 22, 1937, No. 32108. Convention date, Nov. 20, 1936. Addition to 492,369. [Class 38 (ii)] In a commutator switch converter as described in the parent Specification, wherein the contacts 19 constituting the interruption-gap are associated with a main choke 13 and parallel path 25, 26, an auxiliary choke 33 and a parallel path constituted by a discharge vessel 20, for example, is provided. The grid 21 of the latter is energized by an A.C. voltage in synchronism with the supply or is connected to an auxiliary contact 22 of are - resistant material which closes before the main moving contact of the gap 19 and applies a voltage to the grid to initiate the discharge. The resultant current in the vessel 20 and choke 33 is insufficient to saturate the latter, and it absorbs a large proportion of the total voltage-drop and reduces that across the gap to a value such that arcing cannot occur thereat. The vessel 20 may be protected from overloading by means of a resistance 24, or condenser and shunt resistance, or by a reversely-premagnetized choke which only unsaturates with overload currents and so reduces the current. The choke 33 may be short-circuited during switching-off, either by means of a synchronously-driven slip-ring, or by a commutator having resistances between its segments for gradually reducing the current, or by means of a short-circuiting winding with low leakage. The magnetization of choke 33 may be adjusted in readiness for closure of gap 19 by providing a winding 28 which reverses the magnetization during circuit-opening, the winding 28 being in circuit with a further choke 35 fed by an alternating voltage and arranged to be unsaturated during switching-on, or alternatively the choke 33 could be energized by a suitably-arranged D.C. source. The Specification as open to inspection under Sect. 91 contained references to Specifications 492,887, 493,436, and 497,768. These references do not appear in the Specification as accepted.