Modelling of Polymer Coated-based Optical Fiber Sensor for Moisture Measurement in Transformer Oil

Optical fiber based on the polymer coating is one of the best options for water detection sensors in liquid insulation. The water diffusion can be simulated through the finite-element method (FEM) as it provides the finite element analysis to determine the performance of the moisture sensor based on optical fibers. In this work, a commercial COMSOL Multiphysics software was used for the FEM simulation of the coated optical fiber based moisture sensor. The response of the sensor was estimated for different thickness to select the coating thickness before the hardware design to opt for the best sensitivity. The electric field propagation used the 2D model and was estimated by using the boundary mode analysis and frequency domain study. Transport dilute species uses 3D model species to study the diffusion of water into the polymer by varying the thickness and concentration of water (mol/m
³
). The light propagation was simulated based on electromagnetic fields and water diffusion using Fick's law. The modelling of the sensor was done, and the response time required for the sensor was estimated along with the effect of the electric field with varying thickness of PVAc coating.