Patent ID: 11892488

Abstract:
The present invention relates to a method and monitoring device, for monitoring N number of transformer bushings operating in substantially the same environment. N being any number more than 1. The method comprises estimating an absolute value for the capacitances of each of the bushings, the absolute values for the capacitances being denoted Cx, and estimating an absolute value for the loss factor or the power factor of each of the bushings, the absolute values for the loss factors or the power factors being denoted Fx. X is a number representing which bushing the value is associated to and X larger than 1. The method further comprises calculating Δ-values for all C values and Δ-values for all F values, according to: ΔCX=CX−CX+1, for all values up to, and including, ΔCN−1,ΔCN=CN−C1, for ΔCN,ΔFX=FX−FX+1, for all values up to, and including, ΔFN−1,ΔFN=FN−F1, for ΔFN, and determining whether the Δ-values are within predefined ranges.