| 摘要 |
<p>In a variable transformer, two high-conductivity brushes are mounted in a carriage and adapted for longitudinally traversing the transformer winding to contact exposed segments of the winding. By relatively elevating and exposing the odd and even turns along two different traverse paths, contact with the individual odd and even turns is obtained by the dual brush system without short-circuiting adjoining turns, the brushes being interconnected through an external current-limiting or compensating circuit. Spacings between exposed segments of the winding along these respective traverse paths are filled with dielectric material and are wider than the high-conductivity brushes; thus these brushes can never short circuit adjacent turns. The brushes are positioned so that at all times at least one of them contacts an exposed winding segment. Potential differences between exposed winding segments contacted by respective brushes are offset by the voltage difference compensating circuit, such as a diode circuit, connected between the brushes, whereby no turn-to-turn current can flow, irrespective of the external load conditions being applied to this compensating circuit. The winding or windings are advantageously closely coupled to the magnetically permeable core, thereby minimizing leakage flux and associated leakage reactance. Very large size variable transformers now become feasible by employing this invention.</p> |
