FlowElectrification inPowerTransformers: Electrical Modeling

A charge zonenamedelectrical double layer exists atasolid-liquid interface. Theliquid flowinduces aphenomenon called FlowElectrification: itgenerates a streaming current (caused bytheconvection ofcharges present intheliquid) andapotential rise inthesolid (if this oneisinsulated fromtheground). Thesepotentials mayreach values highenough toproduce electrical dis- charges andprovoke accidents. Although this phenome- nonhasbeenidentified along time ago, its physical de- scription rests unknown (production anddisplacement ofcharges, equilibrium, etc.). Aspartoftheresearch program ofElectricite deFrance, aprototype sensor dedicated toflowelectrification characterization atthe interface between pressboard andoilhasbeendevel- opedwiththeUniversity ofPoitiers. Inthis paper we propose touseanelectrical analogy tomodelthese processes intheprototype. Thiselectrical modelis based ontheanalysis ofexperiences carried outwith the sensor.