Dual Optical Measurement for Early Detection of Tracking in Polymeric Insulators Using Fluorescent Fiber and Emission Spectroscopy

One of the major failure mechanisms in outdoor polymeric insulators is tracking. This paper presents a novel dual-optical measurement system which combines fluorescent fiber sensing and optical emission spectroscopy (OES) for early detection of tracking in insulators. The proposed system captures both the time dependent temporal features and the wavelength dependent spectral energy of the discharges simultaneously. The analysis conducted with large dataset of more than 1,000 fluorescence pulses and 3,000 spectral acquisitions during IEC 60587 tests. The progressive shift is observed in the photon emission energy from ~3.75 eV during the initial surface discharge to ~1.37 eV during the tracking stage. In addition, the stage-dependent progression of the fluorescence-based temporal features, such as rise time, pulse width, and energy, has also been investigated. By unsupervised t-SNE clustering, clear separability of degradation stages was visualised, with a silhouette score of 0.72 and 0.88 for OES and fluorescence, respectively. Field representative validation carried out on a polluted 11 kV insulator confirmed that these optical signatures remain consistent under practical conditions. The proposed method is non-contact, immune to electromagnetic interference, and suitable for automated field monitoring.