Search

This paper presents a new technique based on vibration measurement to diagnose power transformers, which is called the onload current method (OLCM). It can acquire the fundamental frequency component of the core vibration signal without running the transformer at the open-circuit condition. The diagnostic method adopted and the experimental test results are reported. Tests have been performed at normal operating conditions in both the manufactory and the laboratory. With the tests performed in the manufactory, the vibration characteristics of transformer windings and core are described, and then the principle of OLCM is introduced. To verify the validity of OLCM, the laboratory tests are conducted which relates the transformer vibrations to the simulative fault. But the presented method was verified on a 5-kVA transformer which is a very far cry from an actual power transformer. It needs to be developed further before OLCM can be used effectively on the transformer in the field. Index Terms--Core, magnetostriction, onload current method (OLCM), transformer, vibration, windings.

Filter capacitors in an HVDC converter station produce audible noise, which can be as loud as that of converter transformers and, therefore, needs to be reduced. Compressible space component (CSC) absorbers can be used to reduce the audible noise due to their broadband frequency and outstanding performance. In this paper, a mechanical model of a CSC absorber is proposed as an audible noise reduction measure for the filter capacitor in the HVDC converter station and then three CSC absorbers with different gas volumes are designed and installed at the bottoms of capacitors, respectively. Audible noise experiments of the filter capacitors with different CSC absorbers are performed and the experimental results are compared with those of a regular filter capacitor. Results indicate that the CSC absorber is a broadband absorber and is effective to reduce audible noise of the filter capacitors. [ABSTRACT FROM AUTHOR]