Localization of Changes in a Model Winding Based on Terminal Measurements: Experimental Study

By using some properties of driving-point functions and adopting an iterative circuit synthesis approach, the location, extent, and type of change introduced in a model winding could be identified, based on terminal measurements. In this study, a model winding was used. From knowledge of its measured short-circuit and open-circuit natural frequencies, and pertinent winding data, an equivalent circuit was synthesized (called reference circuit). Next, changes were introduced at different locations in the model winding and its natural frequencies were measured. Corresponding to every new set of measured natural frequencies, a new circuit was synthesized (with topology remaining unchanged). A comparison of these circuits with the reference circuit revealed that a mapping could be established between changes introduced in the model winding and those predicted by the synthesized circuits. Many case studies are presented by considering continuous-disc and interleaved winding representations. Reasonably good results were obtained. Thus, localization of changes, based on terminal measurements, is shown to be a possibility. So, it is believed that these findings could be of some assistance in addressing the ultimate task of locating mechanical deformations in actual transformer windings.