International Conference On Access To Recent Advances In Engineering And Digitalization (ARACONF), Kayseri, Türkiye, 5 - 07 Mart 2020, ss.82-83
In this study, the optimization of sensing parameters (frequency, sensitivity) was investigated for the diaphragm-based Fabry-Perot interferometric fiber optic pressure sensor (DTFP-FOBS) for detection of partial discharge (partial discharge, PD) formed in high power transformers. The dimensions and detection parameters of the DTFP-FOBS are determined by the diaphragm used in the sensor. The radius and thickness values of the diaphragm used in determining the sensor dimensions are the most effective parameters. In order to detect PD, DTFP-FOBS mostly use silica (SiO2) as diaphragm material. However, the reduction of the radius of the SiO2 diaphragm ensures the resonance frequency (900 kHz-3 MHz) of the sensor to rise too high and goes out of the PD detection band (20 kHz-200 kHz). In addition, the sensitivity of the sensor, whose diameter is reduced, decreases. To eliminate these disadvantages, cellulose triacetate (cellulose triacetate, CTA) has been proposed as an alternative polymer diaphragm. For this purpose, sensor sensitivity and resonance frequency parameters were compared thanks to simulation studies of both diaphragms with different radii and thicknesses using the finite element method. In the light of the simulation results obtained, the fundamental frequency of the CTA diaphragm was calculated as 197 kHz at the radius of 225 μm and the thickness of 20 μm, while the smallest radius value at which SiO2 could reach this frequency was determined as 530 μm. Although the diaphragm made of CTA in these geometric dimensions is smaller in size, its sensitivity has doubled. As a result, it has been observed that the use of CTA as a diaphragm material in DTFP-FOBS specifically for PD application, sensor dimensions can be reduced by 66% compared to SiO2 diaphragm.