Transformer Winding Material Identification Methods Based On Capacity-volume Ratio And Resistance Temperature Coefficient

Distribution transformer winding material is closely related to its operation performance. A feasible transformer winding material identification method is helpful to improve the safety and reliability of distribution network, and it has important practical significance and engineering value. Based on the analysis of copper and aluminum winding transformer property comparison, two transformer winding material identification methods have been proposed and proved by experiment.Based on the designing process and statics of transformer, differences of structural parameters between copper and aluminum windings have been identified first in the paper, followed by comparisons of several properties of both the copper and aluminum windings. The analysis results indicate that thermal stability, winding instability, bending mechanical strength and insulating property of aluminum winding transformer act equivalently to those of copper winding transformer. And the radial mechanical strength as well as ultimate capacity of aluminum winding transformer is slightly lower, while the axial mechanical strength is much lower. Besides, the aluminum winding transformer is much advantageous in its cost and machinability.After theoretical derivation and interrelation analysis on transformer performance parameters no-load loss P0, no-load current I0(%), load loss Pk and short circuit impedance Uk(%), it’s concluded that only by increasing the cross sectional area of windings that the four performance parameters can be guaranteed to satisfy the related national standard. And the transformer winding material identification method based on capacity-volume ratio has been presented by further analysis of structure differences of aluminum winding transformer. Combining with actual transformer parameters, the feasibility of this method has been validated.Aiming at difference of copper and aluminum resistance temperature coefficient, the relations between resistance and temperature of copper and aluminum have been analyzed. Then another transformer winding material identification method based on resistance temperature coefficient has been proposed. Finally the flexibility of this method has been verified by copper and aluminum wire, small transformer and distribution transformer experiments.The investigation and comparison between copper and aluminum winding transformer analyzed in this paper is beneficial to recognize the pros and cons of aluminum winding transformer clearly, and the work of research provides certain guiding indications for its further development and application. The identification methods proposed in this paper can be employed to identify the aluminum winding transformer in power system, which may be significant for reducing safe risks and potential economic loss.