Polyvinylidene fluoride thin film-based magnetic-type capacitive probe

Abstract

The invention discloses a polyvinylidene fluoride thin film-based magnetic-type capacitive probe, and aims to provide a capacitor probe with high signal coupling efficiency. The polyvinylidene fluoride thin film-based magnetic-type capacitive probe comprises a polyvinylidene fluoride thin film, a conductive rubber gasket, a metal electrode plate and a back panel, wherein the polyvinylidene fluoride thin film is attached onto a surface of an equipment shell, the conductive rubber gasket, the metal electrode plate and the back panel are sequentially laminated on a surface of the polyvinylidene fluoride thin film, a groove body is arranged on the back panel and is used for accommodating the conductive rubber gasket and the metal electrode plate, a NdFeB magnetic snap is arranged at one side,deviating from the equipment shell, of the back panel and is used for absorbing and fixing the equipment shell, the polyvinylidene fluoride thin film is used as a capacitive medium between a measuredequipment shell and a sensor and is used for coupling a grounding transient voltage caused by a local discharging electromagnetic wave, the polyvinylidene fluoride thin film and the equipment shell are connected by a magnetic-type lamination structure in a form of the NdFeB magnetic snap, a resistor and a capacitor form a detection loop, reasonable resistance and capacitive parameters are selectedaccording to a bandwidth range of a post amplifier, and a voltage signal is in coaxially transmitted and is led out of a voltage signal on the resistor.

Description

technical field [0001] The invention relates to the technical field of power equipment state monitoring and fault diagnosis equipment, in particular to a magnetic capacitance probe based on a polyvinylidene fluoride film. Background technique [0002] Switch cabinets, circuit breakers, cables and other power equipment are widely used in power grid power transmission, but they have a compact structure, many internal units, low insulation margin, and a high probability of insulation damage or aging. Most insulation defects can be manifested as continuous or intermittent partial discharges under high electric fields, thereby accelerating the aging of equipment insulation systems. Therefore, live detection or on-line monitoring of partial discharge is an important technical means for the operation and maintenance of power equipment, and it has been more and more widely used in the power supply department and power consumption department. Due to its low cost, flexible configurat...

AI Technical Summary

Problems solved by technology

However, the initial signal coupling efficiency of capacitive sensors used in ground wave detection is low, and it is difficult to effectively detect weak discharges with small internal discharges, and when the electromagnetic interference on site is strong, its sensitivity and signal-to-noise ratio are often difficult. Meet the measurement requirements

[0003] In addition, the coupling capacitance of the traditional partial discharge ground wave sensor uses the paint surface or air gap between the electrode sheet and the equipment cavity shell to form a dielectric gap with a certain capacitance. However, it can be seen from the calculation of the coupling efficiency that the The natural capacitance formed has limited efficiency when coupling the voltage to ground. The main reason is that the dielectric constant of the paint surface or air gap is low, between 1 and 3. Therefore, it is necessary to increase the capacitance value by increasing the area of ​​the sensor electrode plate. However, this method will increase the coupling path of background noise and increase the noise threshold level at the same time, and generally has a limited effect on improving the signal-to-noise ratio of the sensor.

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