Stability of fiber Bragg grating sensors for integration into high-voltage transformers for online monitoring

Based on the changes occuring on the electricity market, online monitoring of h-v transformers becomes an important aspect to supervise the actually operating conditions of old devices and to assess the residual lifetime. The use of optical sensors based on fiber Bragg gratings offers the possibility to measure the temperature and the partial discharges directly at the active part of h-v transformers. For a successful integration of the FBGs inside the transformer the long-term stability and optical fiber´s influence on the dielectric strength of transformer oil is investigated.