GB497758A - Improvements in or relating to moving contact electric current converters - Google Patents

Abstract

497,758. Converting. SIEMENSSCHUCKERTWERKE AKT.-GES. June 26, 1937, No. 17829. Convention date, June 29, 1936. Addition to 492,369. [Class 38 (ii)] In a commutator switch converter in which sparkless break at the contacts 14 is obtained by connecting in series therewith a saturable choke 13 and in parallel therewith an impedance path comprising, for example, a condenser 23 and resistance 24, as described in the parent Specification, an auxiliary alternating voltage of adjustable phase and magnitude is injected into the circuit so as to force current through the series choke 13 immediately before closing of the contacts whereby the contacts are relieved of operating voltage at the moment of closing. The auxiliary voltage may be produced by a generator driven synchronously with the supply voltage and adapted to supply voltage of the required wave form. Alternatively, the auxiliary voltage may be produced by a transformer 20, the primary 21 of which is excited from the supply network 11 through a phase shifter 25. A D.C. excited biassing winding 19 may be provided on the transformer 20 to enable the rectangular voltage impulses produced in the secondary to be shifted in phase so that the impulses of unwanted polarity do not interfere with the operation of the choke 13 during opening of the contacts. Specifications 492,807 and 492,887 are referred to.