Frequency Response Measurement of a Power Transformer.

An abstract submitted for:

The 14

th

_{International Conference on Quality in Research (QiR 2015)}

Lombok, Indonesia

10 – 13 August 2015

Frequency Response Measurement of a Power Transformer

W. G. Ariastina, I N. S. Kumara, C. G. Indra Partha, I G. Dyana Arjana, I W. Arta Wijaya and A. A. N. Amrita

Department of Electrical and Computer Engineering, Udayana University, Bali-80362, Indonesia

Abstract:

Power transformers play major roles in delivering the electrical energy. Unpredictable major events such as earthquake and external short circuit may affect the initial position of transformer windings and core. Displacement of windings may be occurred, which further may cause the torn of insulating paper and pressboard. This condition obviously may affect the insulation integrity of the transformer. Damage on the transformer insulation may lead to an insulation failure, hence causing interruption of power delivery. In order to assure the good condition of a transformer, an immediate inspection of the insulation condition after those major events should be carried out. The inspection should also be carried out after relocation and shipment of a transformer.

Sweep frequency response analysis (SFRA) has been used widely for determination of transformer windings and core condition. This technique utilises the electrical transfer functions of the transformer windings over a wide range of frequency. The low voltage with a variable frequency signal is injected into one winding terminal and the response signal is measured at the other terminal. The frequency response measured from a particular winding then is compared to the available reference response data. The SFRA condition monitoring technique may assist engineers to detect abnormalities in transformers such as winding deformation and displacement, shorted or open turns, faulty grounding, core movement, and other internal structure and connection problems.

This paper presents results of SFRA test on a power transformer. The SFRA test results are accompanied by a set of DGA and PD test results. The combined test results indicated that there is an abnormality in the transformer windings that causes very large impulse during ultrasonic test. The serial DGA tests showed the beginning of insulating paper degradation. This integrated monitoring technique has been very useful in indicating the possible occurrence of failure within the transformer windings.

Keywords: SFRA, condition monitoring, power transformer

Contact details:

W. G. Ariastina

Program Studi Magister Teknik Elektro Universitas Udayana

Jalan PB. Sudirman Denpasar, Bali - 80000 I N D O N E S I A

Tel/Fax: +62 361 239599 Email: w.ariastina@unud.ac.id