Study on Vibration Detection of On-Load Tap-Changer Faults by Fiber Grating Sensors based on Cantilever Beam Sensitization

As a core component of power systems, power transformers can suffer from mechanical faults in their on-load tap changers (OLTCs), which may lead to serious grid accidents. To address the limitations of traditional vibration sensors in complex environments such as strong electromagnetic interference and high temperatures, this paper proposes a fiber Bragg grating (FBG) vibration sensor based on a cantilever beam sensitization structure. By theoretically analyzing the strain coupling mechanism between the cantilever beam structure and the FBG, a dual-cantilever beam packaged FBG sensor is designed. The sensor is embedded in a KM-type OLTC to simulate four typical faults: loose drive shaft bolts, loose arc plates, contact wear, and spring fatigue. Experimental results show that the sensor can accurately detect vibration signals corresponding to different fault types in an oil-immersed environment, with a frequency measurement error of less than 1%. Additionally, it exhibits advantages such as resistance to electromagnetic interference and high-temperature tolerance. The study verifies the feasibility of using FBG sensors for real-time monitoring of mechanical faults in transformer OLTCs and provides a high-sensitivity solution for the condition monitoring of power equipment.