GB314082A - Improvements in or relating to regulating transformers working in parallel - Google Patents

Abstract

314,082. Siemens - Schuckertwerke Akt.-Ges. June 22, 1928, [Convention date]. Systems depending on static transformers.-To prevent regulating transformers operating in parallel from getting out of step contact devices are associated with the regulating mechanism of each and connected in a circuit controlling a signal, safety or locking device. As shown in Fig. 2, the safety circuit comprises two parallel branches a, b between points 4, 5, both of which are interrupted when drums 1, 2, operated respectively in step with two transformer regulators, fall out of step. The brushes or the contact drums may be coupled to the .regulating gear. Fig. 3 shows a development of the contact mechanism for two transformers each of which includes a sector switch member 101 co-operating with fixed contacts 102 - - 105 and switch members 110, 120 controlling the tap connections to secondary windings 100, 200. The apparatus is operated by spindles 6 geared to maltese cross gear 108 driving the tap switches. The tolerance allowed by the safety contact arrangement 31, 33 depends on the width of the contact brushes and the contact 33 and this may be reduced by introducing contacts intermediate with the contacts 31, 33 and connected by further brushes in a third parallel circuit between the points 4, 5. Fig. 6 shows a system in which two transformers are regulated by reversible motors each controlled by a pair of electromagnetic switches 152, 153 included in the safety circuit. Both the switches for one direction are controlled by a switch 154 or 157 which may be energized by a push button 158 or 159, the push button contacts being interlocked by cross connections to prevent simultaneous energization of switches 154, 157, and each electromagnetic switch making a maintaining circuit controlled by the safety contacts between the points 4, 5. The push button circuit includes contacts 165, 166 on each regulator such that the control circuit cannot be closed unless all are correctly positioned. Any transformer can be cut out, by switches 168 arranged to shortcircuit the contacts 165, 166 and the safety contact devices (not shown) associated with that transformer being operated by the main transformer switch.