Pressure monitoring of a transformer oil tank can grasp the pressure change process caused by gas production when severe internal defects occur and take timely measures to ensure the safe operation of the transformer. Existing pressure sensors generally use metal encapsulation or have an air cavity structure

threatening the transformer's insulation if it is directly used inside the transformer. To this end

this paper proposes a method for developing a high-sensitivity

large-range

and metallization-free optical pressure sensing device with temperature compensation. Fiber grating is encapsulated by fluorosilicone rubber and supplemented by an epoxy resin shielding shell on the outside. At the same time

a double-grating vertical arrangement is adopted to improve pressure measurement sensitivity

further avoiding the influence of temperature rise caused by a defect of the transformer on the measurement result of the sensor. In addition

by optimizing the geometric structure of the internal sensitizing element

pre-stretching length of the fiber grating

gap distance

and other parameters

probe size can be reduced while ensuring the sensor's performance. Results show the proposed method can meet the requirements of sensor fabrication with different sensitivities and ranges

and to a certain extent

both high sensitivity and extensive ranges can be taken into account. The sensitivity of the fabricated prototype is 15 pm/kPa

and the range is about 0.2 MPa. At the same time

the metal-free feature of the sensor makes it suitable for use in various oil-immersed power equipment. It records oil pressure changes caused by oil discharge breakdown

making it sensitive to small pressure changes in early failures.