Diagnostics of Oil-Paper-Insulations Using Relaxation Currents
Stefan Tenbohlen Universität Stuttgart
Maik Koch Hochschule Magdeburg
The dielectric response of oil-paper-models was measured with relaxation currents, also known as Polarisation and Depolarisation Currents (PDC). The measurements cover the influences of moisture content in cellulose, a wide temperature range, insulation geometry, ageing state and measurement voltage. At multilayer insulations the dielectric response appears to be nonlinear, i.e. modeling with equivalent circuits according to Debye is hardly possible. The transient behavior of oil conductivity was found to be the reason for nonlinearities and is explored more exactly. The obtained set of measurement data was applied on power transformers to determine water content in cellulose.
Keywords: Power Transformer, Monitoring, PD-Measurement, Partial Discharge