Transformer sound level caused by core magnetostriction and winding stress displacement variation

Abstract

Magnetostriction caused by the exciting variation of the magnetic core and the current conducted by the winding wired to the core has a significant result impact on a power transformer. This paper presents the sound of a factory transformer before on-site delivery for no-load tests. This paper also discusses the winding characteristics from the transformer full-load tests. The simulation and the measurement for several transformers with capacities ranging from 15 to 60 MVA and high voltage 132kV to low voltage 33 kV are performed. This study compares the sound levels for transformers by no-load test (core/magnetostriction) and full-load test (winding/displacement ε). The difference between the simulated and the measured sound levels is about 3dB. The results show that the sound level depends on several parameters, including winding displacement, capacity, mass of the core and windings. Comparative results of magnetic induction of cores and the electromagnetic force of windings for no-load and full-load conditions are examined.

Model of the Magnetostrictive Hysteresis Loop with Local Maximum

“…Such form of magnetostrictive characteristic model is more convenient for technical applications. For this reason, Equation (3) was successfully used for the technical modeling of magnetostrictive actuators, especially with cores made of giant magnetostrictive materials, such as Terfenol-D [18,19].…”

Load noise prediction of a power transformer

“…Even though empirical equations (Girgis et al (2011) and Hsu et al (2017)) and multiphysics analysis (Hu et al (2016)) were proposed to predict the load noise of transformers, they have the following limitations. As the previously published prediction equations for the load noise only considered the electrical specifications and design parameters without considering the winding vibration, the predicted noise level shows a large deviation from the actual value.…”

“…Multiphysics analysis has drawbacks in that it requires significant computation time and cost because it requires complex modeling including that of electromagnetic, mechanical, and acoustic fields and large-scale computations. Accordingly, it is necessary to develop a prediction equation that can calculate the load noise of the transformer relatively accurately in a short time and at a low cost by overcoming the limitations of the two previous methods (Girgis et al (2011), Hsu et al (2017), and Hu et al (2016)). Therefore, to overcome these limitations, this study aims to develop an equation that can predict load noise with relatively high accuracy in a short time by considering winding vibration.…”

Tensor representation of magnetostriction for all crystal classes

“…On the other hand, the presence of magnetostriction may represent a limiting drawback in some technological applications. In power transformers, in fact, the magnetostrictive vibration of the magnetic core has the undesired effect of being a non-negligible source of acoustic noise [16,17].…”