Spatial and spectral resolution of electroluminescence in XLPE

This paper describes a new experimental setup that can simultaneously resolve the spectral and spatial distributions of electroluminescence (EL) at points of stress enhancement in XLPE cable. The set-up consists of a photomultiplier tube (PMT) and a charge coupled device (CCD) camera to simultaneously capture the EL when high voltage is applied to the polymer. The spectra, resolved by interference filters, and the phase relationship of EL with respect to the applied voltage are determined by the PMT. For spatial resolution an area around the stress point is magnified and imaged onto the CCD. The brightness of each pixel of the CCD signifies where and how far from the tip EL is emitted. Thus, space charge formation and the location of the luminescent centers are resolved when the polymeric insulation is subjected to high voltage