To address the issues of insufficient ultrasonic sensing sensitivity and decreased radio frequency sensing performance of existing gas insulated switchgear (GIS) partial discharge (PD) acoustic-magnetic integrated sensors due to the influence of built-in near-field metal

this paper proposes a design method for an integrated acoustic-magnetic sensor based on a new type of insulating medium sandwich structure. The finite element method is used to construct and optimize a simulation model for the ultrasonic and high-frequency electromagnetic wave frequency response characteristics of the sensor

including the GIS metal flange

and to conduct actual measurements. The results indicate that:The insulating sandwich acoustic-magnetic integrated sensor achieves an average sensitivity of 61.2 dB and a maximum sensitivity of 64.5 dB in the ultrasonic frequency range of 20~80 kHz. Compared to non-sandwich sensors

the standing wave ratio in the high-frequency electromagnetic frequency range of 0.3~ 1.5 GHz is less than 4

with a bandwidth improvement of 355.6%. Under different degrees of metallic contamination and protrusion defects

the sensitivity of the ultrasonic sensing of the sandwich acoustic-magnetic integrated sensor exhibits performance comparable to that of commercial GIS PD ultrasonic sensors for the first time. Its high-frequency electromagnetic wave sensing sensitivity is superior to that of non-sandwich integrated sensors under different test voltages

with an initial signal detection amplitude increased by approximately 82.9% and 41.9%

respectively. Additionally

the time difference between the PD electromagnetic wave and ultrasonic signals detected by the integrated sensor aligns with theoretical calculations. The research findings are of significant theoretical and practical importance for the development of acoustic-magnetic integrated sensing technology and the intelligent high-sensitivity diagnosis of GIS PD defects.