Estimation of the Clamping Pressures of Transformer Windings from Vibration Measurements

Abstract

The ability to monitor the level of clamping pressure on transformer windings, that is, the degree of winding looseness, is important in ensuring a high availability of electrical power and to prevent the high costs incurred by unexpected failures. In this paper, three-dimensional computer modelling of a three-phase power transformer from its specifications and geometry was employed to estimate the 100-Hz vibration magnitude of the tank due to the winding vibrations for a particular axial clamping pressure. The experimental and calculated clamping pressures were found to be in good agreement. In order to develop the computer model, it was necessary first to determine dynamically the non-linear modulus of elasticity of the spacers by building a finite-element model of a single winding, determining its eigenfrequencies using an assumed modulus and comparing them with experimentally-determined eigenfrequencies. The actual modulus was then found by trial and error.

Applications of FEM in condition monitoring of transformer clamping system

“…Even though the clamping system of a power transformer winding is critical for its reliable operation, it was found that no direct clamping pressure monitoring system has been developed yet. However, to overcome this problem, many researchers have developed on-load transformer tank vibration monitoring based techniques to estimate the health of power transformer winding clamping systems [7][8][9][10]. Nevertheless, due to the lack of understanding of the dynamic behaviour of winding clamping pressure, none of the existing techniques is reliable [11,12].…”

Understanding the moisture temperature and ageing dependency of power transformer winding clamping pressure

“…Existing literature has revealed that the vibration spectrum of a transformer captured from its tank surface is sensitive to the health of its winding and core clamping systems [52,[149][150][151][152][153]. This chapter is based on two publications authored by the PhD Candidate [154,155].…”

“…Therefore, vibrations in the frequency range 100 Hz -1 kHz, which are generated by the winding and core assembly contain useful information about the structural health of the power transformer [52,127,[148][149][150][151][152][153]. The time-varying electromagnetic forces harmonically excite the winding structure and generate mechanical vibrations.…”