What are the detection principles of SF6 gas leak detection for electrical equipment?- SF6在线监测系统_SF6检漏仪_SF6传感器_SF6密度继电器

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What are the detection principles of SF6 gas leak detection for electrical equipment?

发布时间：2022-04-25 来源：ydlcb 浏览次数：24次

What are the detection principles of SF6 gas leak detection for electrical equipment?

A: At present, there are many methods of SF6 leak detection in the field, and various detection methods of SF6 leak detector mainly use SF6 as a electronegative gas, which has the characteristics of absorbing free electrons. The measurement principles of commonly used leak detectors include ultraviolet ionization detection, ion capture detection, vacuum high frequency ionization detection, negative corona discharge detection, laser imaging detection, infrared spectrum detection, etc.

1) Ultraviolet ionization detection principle: Ultraviolet ionization detection is the use of ultraviolet light to detect the oxygen and sulfur hexafluoride gas ionization, according to their ion migration speed and electron absorption capacity differences, quickly and easily determine the concentration of trace sulfur hexafluoride in the detected gas. The detection principle is that the ultraviolet lamp in the ultraviolet detector pulsates at a oscillation frequency of 2kHZ, emitting 1849×10-10m ultraviolet light. Ultraviolet light is directly irradiated on the photoelectric surface through the network of accelerating electrodes, so that the photoelectric surface emits free photoelectrons. Oxygen and sulfur hexafluoride in the measured gas are adsorbed on these photoelectrons by passing the measured gas between the photoelectric surface and the accelerating electrode. These photoelectrons are ionized into an ionic state under the action of a voltage applied between the photoplane and the accelerator pole, and move towards the photoplane at their respective migration speeds. Because the electronegativity of oxygen and sulfur hexafluoride gas is not the same, the photoelectron capture ability is not the same, the formation of different migration speed, using the phase difference of the ion flow formed by this speed difference, the phase change of the ion flow can be detected, the existence and concentration of sulfur hexafluoride gas can be checked. Weavers SF6 Quantitative leak detector (Winfoss-C1) is designed and tested with this material.

2) Electron capture detection principle: electron capture detection uses radioactive isotope Ni63 as the ion emitter of the detector. This type of instrument only produces signals for gases that are electronegative (such as halogen substances and substances containing O, S, and N molecules), and the sensitivity increases with the increase in the electronegativity of the substance. The detection principle is that when the carrier gas passes through the radioactive source, the high capacity electrons of the beta ray ionize the carrier gas to form positive ions and slow electrons, and then migrate to the positive opposite electrode to form a base flow. When the negative electric gas (such as sulfur hexafluoride) enters the detector from the probe, it captures the slow electrons in the detector to generate negative ions, and the negative ions in the electric field are lower than the free electrons, and the negative ions of the gas to be tested are combined with the positive ions of the carrier gas to become neutral chemicals, which are taken out of the detection room by the carrier gas, and the original base flow is reduced. The reduction of the base flow is proportional to the concentration of the measured gas. In this way, the changed base flow is output as the concentration indication signal through the signal amplifier, so as to meet the requirements of detecting the concentration of the gas.