Chromatic classification of RF signals produced by electrical discharges in HV transformers

The results of investigations into the use of chromatic processing of radio frequency signals emitted from transformers known to be suffering from partial discharging are described. The work formed part of a project operated by National Grid Transco involving several industrial parties and UK universities. The chromatic processing methodology developed at the University of Liverpool has been explored for discriminating between various radio frequency signals measured with different techniques, by Glasgow Caledonian University, UMIST, the University of Southampton and the University of Bath. Such discrimination is based on three chromatic parameters: hue (dominant frequency), lightness (nominal signal strength) and saturation (effective signal bandwidth). The chromatic results are capable of yielding patterns, which appear to be associated with indications of discharges of different types and from different sources/locations.