Application of Sweep Frequency Response Analysis (SFRA) for inter-turn detection of in medium-voltage coils manufacturing

摘要

It is known that for some years it has been developed a technique based on the sweep frequency response analysis (SFRA) for the diagnosis of power transformer windings. Since the first works to nowadays many developments and improvements have been made. The relevance of this method has resulted in the creation of new standards for applying the method, such as CIGRE and IEEE. Since its appearance, the industrial interest of this technique lies in the possibility of identifying small strains that could appear in the coils of power transformers, as a result of forces that occur during a short circuit or any possible shock during transport. Basically, this technique is based on the analysis of the impedance of the windings in the frequency domain. Given that the winding can be modeled as an equivalent circuit with a complex network of capacities, inductances and resistances, its frequency response is unique. Thus, any alteration in the winding results in a variation of the equivalent circuit and therefore its frequency response changes too.