The mechanical strength and integrity of the transformer windings is established by short circuit test. Reactance comparison method and frequency response analysis methods are conventionally used to assess the failures. Concurrent application of various high frequency excitations has also been tested. We show that optimized multisine excitation has the potential of high sensitivity towards displacement identification.

V. Jayashankar

Building materials

Digital signal processing

Electric transformer testing

Frequency response

Insulating materials

Welds

Winding

Comparison methods

CONCURRENT APPLICATIONS

FREQUENCY RESPONSE ANALYSES

HIGH FREQUENCIES

HIGH SENSITIVITIES

MECHANICAL STRENGTHS

SENSITIVE METHODS

Short circuits

WINDING DEFORMATIONS

Transformer windings

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

Sensitive method for detection of winding deformation during short circuit test

Proceedings of the International Symposium on Electrical Insulating Materials

The short circuit test is a special test for proving the mechanical integrity of a power transformer. Conventionally a change in reactance exceeding 2% after the test is an indication of failure. Concurrent high frequency excitation is shown to be more sensitive method for detecting winding deformation. A 'benchmark' layer winding is used to validate the use of high frequency excitation. Axial displacement, compression and buckling of the winding are simulated and the changes are identified. It is clearly established that for all these changes high frequency excitation is more sensitive. © 2009 IEEE.

2009 IEEE Intrumentation and Measurement Technology Conference, I2MTC 2009

On the use of concurrent high frequency excitation during a short circuit test in a power transformer

The ability of a transformer to withstand the dynamic effects of a short circuit test is conventionally evaluated by a measurement of short circuit reactance before and after the test. We propose new techniques for fault detection based on continual assessment during the test. The methods are based on the comparative null method for accuracy measurement in instrument transformers. They include voltage comparison, current comparison and real/reactive power measurements. High resolution sampling based acquisition systems are used to compute changes on a cycle-to-cycle basis. The proposed methods are validated on a number of models including a voltage transformer and a distribution transformer winding. They would be useful for designers in assessing events leading to failure in a more transparent manner. © 2008 IEEE.

IEEE Transactions on Power Delivery

Real-time techniques to measure winding displacement in transformers during short-circuit tests

A new approach for the continual assessment of winding deformation during short circuit test is proposed. The method is validated through FEM analysis of axially unbalanced axisymmetric configurations. Simulation results are shown to validate the proposed method.

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