We propose an objective formulation of the impulse analysis problem from a signal analysis viewpoint. The winding response is quintessentially that of a deterministic network to a finite energy signal, with breakdown and partial discharge being inherently nonlinear events. A significant improvement to the acquisition of waveforms is demonstrated by a virtual instrument approach. It retains the advantages of the time- and frequency-domain methods. The drawbacks of the transfer function method are highlighted and a new piecewise linear approach is proposed for analysis. Experiments on a discrete lumped parameter model of the winding are used to validate the PXI based instrument.

Virtual Instrument for Lightning Impulse Tests

Future template numerical interpretation techniques for PD pulse location in transformer windings

An objective formulation of the impulse testing procedure is proposed based on models for winding response as well as fault models. Experimental validation of the fault models for breakdown and partial discharge (PD) is provided. A new adaptive filtering approach is proposed for analysis during impulse tests. The procedure is validated with experimental investigation on a 10 section lumped parameter network.

Programmable continuous time filters for impulse testing of transformers

Investigations, through a sample evaluation, aiming to evaluate the cause of the high-frequency oscillations presented by distribution transformers in impulse tests reveal that internal imperfections, such as cavities and floating particles, cause these oscillations.

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Investigation of High-Frequency Oscillation Discrepancies Presented by Distribution Transformers During Lightning-Impulse Voltage Tests

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

Experimental results on fault simulations during impulse tests across windings and other specifically designed networks are reported. Both breakdown and partial discharge studies are conducted with digital acquisition of fault records.

V. Jayashankar

Papers

Simulation of faults during impulse tests