GB698595A - Device for switching on a transformer for a short time interval - Google Patents

Abstract

698,595. Switching systems for transformers. BALTEAU, M. J. F. J. Dec. 27, 1951 [Dec. 28, 1950], No. 30195/51. Class 38 (iv). To ensure uniformity of the current impulses delivered by an X-ray, spot-welding, or other intermittently energized transformer 5, a contact 11 of a switch I vibrates between contacts 9, 10 in synchronism with the supply to the transformer when the latter is energized and comes to rest on one of these fixed contacts when the energization of the transformer is interrupted, thereby preparing a circuit which ensures that when the transformer is next to be energized it will be connected to the supply at such a point in the voltage cycle that current flows in the same direction as immediately prior to the previous interruption. In the arrangement shown, switching is effected by a relay B1 having contacts 6 controlling the supply circuit to the transformer and contacts 14 controlling the connection of the grids 19, 20 of thyratrons T2, T3 to a peaking transformer G energized from the same supply, the thyratrons alternately energizing (when contacts 14 are closed) windings B2, B3 and so causing the vibration of the contact 11. Closure of a time switch A prepares a circuit for the energization of relay B1 over a further thyratron T1, which subsequently conducts under the control of the peaking transformer, the polarity of the half cycle in which conduction occurs being determined by which of the contacts 9, 10 is engaged by the contact 11 which, in turn, is dependent on the polarity of the last half cycle of energization of the transformer. Relay B1 may be so adjusted that its contacts close threequarters of cycle after energization of its coil, so that the contacts close when the supply voltage is passing through zero. The switch A may also be such as to cause disconnection of the transformer at a zero voltage point of the cycle.