Changes in resonant frequencies of a winding can identify the location of breakdown during impulse tests. This is difficult with a uniform winding. We propose the use of concurrent UHF antenna and winding currents in order to locate breakdown. The work can be extended to identify partial discharge events in dry type transformers.

V. Jayashankar

Antennas

Building materials

Frequency response

Insulating materials

Natural frequencies

Partial discharges

Transformer windings

CURRENT RESPONSES

DRY-TYPE TRANSFORMERS

Resonant frequencies

UHF ANTENNAS

WINDING CURRENTS

Winding

IIT Madras is a public technical and research university located in Chennai, Tamil Nadu. Founded in 1959, it is recognised as an Institute of National Importance.

IIT Madras has been ranked as the top engineering institute in India for four years in a row by the National Institutional Ranking Framework of the MHRD

It currently offers undergraduate, postgraduate and research degrees across 16 disciplines in Engineering, Sciences, Humanities and Management. About 596 faculty belonging to science and engineering departments and centres of the Institute are engaged in teaching, research and industrial consultancy.

IIT Madras

Location of breakdown in windings using concurrent UHF antenna and current responses

Proceedings of the International Symposium on Electrical Insulating Materials

A consistent laboratory reproduction of waveforms during impulse tests with solid insulation materials has been a difficult task. Carbon polyethylene composites can serve as benchmarks for such studies. Experimental results on films and a practical voltage transformer (VT) are shown that can help develop signal analysis tools.

Carbon-polyethelene composites as bench marks for breakdown studies in windings

A method is proposed for recognizing PD events within a winding during impulse tests using a lock-in amplifier technique. The resonant frequencies of the winding serve as the basis of selection of the lock-in amplifier reference frequencies. It is implemented with a virtual instrument and validated with an independent stand-alone lock-in amplifier. A physical model of a winding with discrete elements is used to demonstrate the results. A theoretical basis for the instrument is established using an 'abc' model of PD along with a linear discrete winding model. The influence of location of PD is also addressed. The method will provide online recognition of PD during the impulse test and can be adapted for onsite measurements. © 2007 IEEE.

IEEE Transactions on Dielectrics and Electrical Insulation

A lock-in technique for PD measurement during impulse tests

An objective classification of faults that can occur during impulse tests on power transformers is proposed. It includes nonlinear elements, breakdown, and partial discharge events. An analysis of a layer winding in the time and frequency domains with these faults shows that current assessment methods must be used with caution. A model reference approach is proposed to distinctly improve recognition in such cases. The method is immune to changes of wave shape and the instant of fault is available by observation.

IEE Proceedings: Science, Measurement and Technology

Impulse testing of power transformers - A model reference approach

IEEJ Transactions on Power and Energy

Fuzzy Logic based Fault Classification of Impulse Test Records

IEEE Electrical Insulation Magazine

Partial discharge monitoring of power transformers using UHF sensors. Part I: sensors and signal interpretation

Journal	Proceedings of the International Symposium on Electrical Insulating Materials
Open Access	No