System Overview:
SF6 was synthesized by the French chemists Moissan and Lebeau in 1900. Since the 1960s, the SF6 gas has been widely used in the power system due to its excellent insulating and arc-quenching properties. Today, SF6 gas has almost become the sole insulating and arc-quenching medium for high-voltage and ultra-high-voltage circuit breakers and GIS.
Sulfur hexafluoride is a colorless, odorless, non-toxic, non-flammable, and non-corrosive gas under normal temperature and pressure, with a gas density of 6.139 g/L. It exhibits strong chemical stability and does not decompose at temperatures between 500°C and 600°C. SF6 boasts excellent electrical insulation and arc-quenching properties, making it widely used in the electrical industry, such as circuit breakers, high-voltage transformers, gas-insulated composite capacitors, high-voltage transmission lines, and transformers. In the power industry, SF6 serves as a crucial medium for arc-quenching and insulation in enclosed medium and high-voltage switches. It is also a simple asphyxiant. Exposure to an atmosphere with oxygen levels below 19.5% can cause dizziness, coma, increased salivation, delayed reactions, nausea, vomiting, loss of consciousness, and death. Exposure to an atmosphere with oxygen levels below 12% can lead to sudden loss of consciousness without any warning, and the inability to自救. The decomposition products of SF6, such as sulfur difluoride (SOF2), sulfur tetrafluoride (SF4), sulfur dioxide difluoride (SO2F2), and sulfur difluoride (SF2), are highly harmful to humans. Therefore, in switchgear rooms equipped with SF6 equipment, inadequate ventilation can lead to a lack of fresh air, oxygen deficiency, or indoor air pollution due to SF6 gas leaks, posing serious threats to the health and even lives of personnel entering the room for operations and maintenance. This presents challenges to the safe operation of the power system. Consequently, China's "Regulations for Safety in Electric Power Work" specifically stipulates that oxygen and SF6 detection and alarm devices must be installed in relevant locations, along with necessary ventilation and air exchange equipment.
The GTS-II SF6 Gas Leak Detection and Alarm System is specifically designed to address the aforementioned issues. The system consists of four major modules: the operation control panel, detection host, centralized power supply unit, and gas sampling unit. It can real-time detect SF6, environmental temperature and humidity, oxygen content, and control the on/off of fans, air conditioners, and more. The system automatically records various alarm and real-time data, and controls fans and other equipment according to the set mode. It is an intelligent collection system that can be flexibly configured according to specific requirements of various application scenarios and can provide an interface for remote communication devices to enable remote control, remote measurement, and remote signaling functions.
The GTS series SF6 gas monitoring system is an open system platform that integrates laser technology, data collection, data processing, and communication technology. All its functions are designed in a modular manner, facilitating engineering installation and maintenance.
This system can be widely applied in various SF6 switchgear rooms, integrated switchgear rooms (GIS rooms), and other similar locations.
Section II: SF6 Leak Detection Principle
Spectra can represent the dynamic states of atoms and molecules within a substance. This internal motion of the substance can be manifested in the form of radiation or absorption of energy, i.e., electromagnetic radiation, and spectra are arranged in order of wavelength. Since the motion of atoms and molecules is diverse, so is the representation of spectra. According to wavelength and measurement methods, spectra can be categorized into: gamma rays, X-rays, optical spectra, and microwave spectroscopy. Optical spectra can further be divided into vacuum ultraviolet, near-ultraviolet, visible, near-infrared, and far-infrared spectra.
Experiments have proven that when infrared light of specific wavelengths passes through SF6 gas, these gas molecules absorb the infrared light of specific wavelengths, and the absorption follows Lambert-Beer's law of absorption, meaning the absorption is naturally exponential to the concentration of SF6 gas.
By employing these principles, we designed an optical device using an active suction method. When the sampled gas contains SF6, the intensity of the infrared light in the detection chamber diminishes accordingly. Based on the degree of reduction, we can calculate the SF6 gas concentration using the Lambert-Beer Absorption Law.
This product employs infrared spectroscopy absorption technology for SF6 gas leakage detection. Compared to other detection techniques, the use of infrared spectroscopy absorption for detecting SF6 gas offers high precision, stability, and reliability, without being restricted by environmental conditions such as temperature and humidity.
