Non-contact fiber optic ultrasonic sensor

Abstract

A non-contact optical fiber ultrasonic sensor, in which an optical fiber fixing tube is radially arranged on the left side of the center plane of the height of the side wall of the optical fiber installation ring, and a single-mode optical fiber and an optical fiber collimating mirror with overlapping centerlines are arranged in the optical fiber fixing tube. The right end of the mode fiber is set on the left end face of the fiber collimator, and a reflector is set on the right side of the center plane of the height of the inner wall of the fiber installation ring. The angle between the reflector and the incident direction of the horizontal laser beam is 45°. The lower end of the fiber installation ring A hollow plug is provided inside, and a sensing film is provided on the upper end of the hollow plug in the optical fiber installation ring. It has been proved by experiments that the invention has good response characteristics, stability and sensitivity to ultrasonic signals in the 300KHz band. In the real-time acquisition mode, the spectral signal-to-noise ratio is high, and it is suitable for detecting ultrasonic waves generated by partial discharge in transformers and can be used for real-time acquisition ultrasound.

Description

technical field [0001] The invention belongs to the technical field of sensors, and in particular relates to ultrasonic sensors. Background technique [0002] The power transformer is an important electrical equipment in the power system. It is in a pivotal position in the power system. Once a fault occurs, a large-scale power outage may occur, which will bring great losses to the power system and the national economy. Therefore, the power system attaches great importance to the power transformer. state, especially the health of its insulating media. Since the insulation structure of power transformers usually adopts oil-immersed composite insulation with good insulation performance, with the development of power systems and the increase of voltage levels, partial discharge has become an important cause of insulation degradation of power transformers, so the detection and evaluation of partial discharges is also important. It has become an important means of monitoring its ...

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Problems solved by technology

Although the electric pulse method is the basis of partial discharge research, the electric pulse signal will have a lot of interference (usually above several thousand PCs) when it is detected in the field, and it is difficult to obtain the discharge signal correctly. In addition, the problem of online calibration and online results Equivalence with offline results and other issues have long plagued the online detection of transformer partial discharge by electric pulse method. At present, in the field, engineers and technicians often pay more attention to the detection of partial discharge of operating transformers, especially when the discharge capacity is large. , by detecting partial discharge to determine the degree of damage to the transformer insulation

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