Adding Intelligence to Ceramic Insulators by Markku Ruokanen
The move toward digitalization of substations brings with it several challenges when it comes to data capture and transmission. Fibre optic technology is one of the solutions possible since it is immune to EMI/RFI and has also achieved a high level of maturity that has helped drive down cost. Moreover, optical sensor technology does not need a power source at the measuring point and the light source can be hundreds of meters away and outside the substation itself. Installing fibre optic cable at a substation is another challenge since it must pass through the insulators. Fortunately, manufacture of fibre optic post insulators has become possible in an industrial, cost-effective manner using isostatic technology. The fiber optic hole is located on the neutral axis and as such does not affect mechanical performance while making it possible to measure acoustic waves and vibrations inside the ceramic post. The stress level of the insulator does not affect acoustic signal frequency or propagation within the material itself. Data collected, once filtered and analysed, can then be used for substation monitoring and in this sense is a first step toward an ‘intelligent’ insulator that senses its environment and provides important system data needed for substation management. This presentation explains the method of manufacturing ceramic insulators containing a fibre optic hole. It also explores potential future applications in monitoring forces, movements and vibrations of ceramic insulators as part of the digital substation.