“Coupling thermal step method and thermo-stimulated currents in polymers”

In dielectric materials submitted to high voltage, we can observe an accumulation of space charges which modify the residual electric field distribution. Consequently, the space charges are one cause, between others, of electrical breakdown of materials. Therefore space charge measurements are of high interest. We have set up a new method to measure residual space charges in insulating materials. The principle is based on a thermal step which is diffusing through the sample, crossing over the interfaces without causing the charges to recombine because the maximum of temperature is too weak-therefore the measurement is reproducible. It permits making measurements on various thicknesses and geometries, from films to cables. We present here some results on XLPE obtained by the Thermal Step (TS) method coupled with Thermo-Stimulated Discharge Currents (TSDC)