GB246855A - Improvements in or relating to automatic voltage limiting means - Google Patents

Abstract

246,855. International General Electric Co., Inc., (Assignees of Allgemeine Elektricitõts Ges.). Jan. 29, 1925, [Convention date]. Controlling heating systems.-In an arc welding system, wherein a small voltage is to exist between an electrode l and work m, before these contacts com plete a circuit, and thereafter an increased voltage is impressed upon the circuit, a single automatically operated switch f is used. Before the electrodes l, m engage with each other, they are at a difference of potential due to the winding a of a transformer. Immediately after engagement, current flows through coils g, h, k, causing the switch to close and complete a circuit through both windings a, b of the transformer. a steadying choke c, holding-on coil k, and the arc between the contacts l, m. When the arc is broken, the voltage of the winding b is impressed upon coils g, h so that they aid each other, and upon an opposing coil i which neutralizes the effect of coils g, h, so that the switch drops to its initial position. An impedance z. prevents the magnetizing current through thecombined coils g, h, i attaining such a high value that the switch is prevented from dropping. A modified arrangement is described in which the coil i is shunted across part of the choke c, in which case it is possible to dispense with the coil k.