Numerical and Experimental Validation of Discharge Current With Generalized Energy Method and Integral Ohm´s Law in Transformer Oil

The discharge currents were evaluated and validated using the generalized energy method and the integral Ohm´s law combined with the recently developed discharge analysis technique for dielectric liquid media, such as transformer oil. The terminal current in voltage-driven systems was found to play an essential role in characterizing the pattern of electric discharge, such as corona, breakdown, etc. Until now, the generalized energy method and integral Ohm´s law were normally adopted to evaluate this terminal current, but no experimental validation was reported and no test was performed in a dielectric liquid media. The generalized energy method can be derived directly using Poynting´s theorem and is well suited for the finite element method. As an alternative approach, the integral Ohm´s law can be applied to multiport systems. To confirm the numerical results, an experimental setup was proposed with a multiport system composed of a tip and separated conducting ring shells. The numerical results were compared with those from experiments, which would be the first trial in a dielectric liquid with a multiport system. The calculated current profile was similar to that from the experimental result, but the breakdown voltage from the calculated results was relatively high.