Abstract:Sulfur hexafluoride (SF₆) is a potent greenhouse gas with a global warming potential index (GWP) of 23 900 times that of carbon dioxide and an atmospheric lifespan of 3 200 years. It is widely used in high-voltage switchgear. The widespread use of SF₆ poses a huge potential threat to the greenhouse effect problem, and limiting its use in power switchgear is an effective way to promote the development of the green power industry. The current situation, trends, and critical technologies of environmentally friendly switchgear at home and abroad in recent years were reviewed in this article. The development of environmentally friendly switchgear switches is based on the development of SF₆ removal technology-environmentally friendly alternative gas-insulated switching and vacuum breaking + environmentally friendly gas-insulated switching. The insulation performance, breaking performance, and decomposition characteristics of SF₆-alternative gas C₄F₇N, C₅F₁₀O, perfluorocarbons (c-C₄F₈, C₃F₈, CF₄), CF₃I, and HFO were summarized and compared. The current status and development trend of existing environmentally friendly gas-insulated switchgear products was introduced. Through comparative analysis, it was recognized that C₄F₇N, C₅F₁₀O are promising alternative gas solutions. The critical technology of vacuum breaking + environmentally friendly gas-insulated was described. The results indicated that solid particles generated after multiple discharges of CF₃I and c-C₄F₈ in environmentally friendly gases affect their insulation performance. The weak dielectric strength of perfluorocarbon gas restricts its research progress. Comparative analysis showed that C₄F₇N and C₅F₁₀O promise gas alternatives, and the insulation and breaking performance of C₄F₇N and C₅F₁₀O mixed gases meet the equipment requirements. However, their insulation performance is sensitive to the uniformity of the internal electric field in the equipment, and the irreversible decomposition process produces complex products. At present, high-voltage gas environmentally friendly insulated switchgear has developed to 170 kV/50 kA, using three types of environmentally friendly mixed gases: C₅F₁₀O/O₂/CO₂, C₄F₇N/O₂/CO₂, and C₄F₇N/CO₂. The critical technology of vacuum breaking + environmentally friendly gas-insulated was described. The current research status of high current vacuum arc magnetic field control technology, vacuum arc extinguishing indoor and outdoor insulation technology, vacuum interrupter X-ray leakage and temperature rise characteristics was summarized. Based on this, the current situation and future development trend of vacuum-breaking type environmentally friendly electric switching equipment were summarized. The results indicated that longitudinal magnetic control is an effective method of arc control. However, research on vacuum arcs under longitudinal magnetic fields mainly focuses on small gaps. Analysis suggested that a significant challenge will be developing longitudinal magnetic control for vacuum switches to higher voltage levels. By optimizing the opening curve of vacuum circuit breakers, the efficiency of longitudinal magnetic control can be effectively improved; The development of vacuum switches towards higher voltage levels poses a considerable challenge to vacuum interrupters’ indoor and outdoor insulation. Increasing the contact gap and adopting multiple breaks are currently the main ways to improve the insulation capacity of the arc extinguishing chamber. However, there are problems with vacuum insulation saturation and difficulty in voltage sharing. Environmental friendly gas pressurization and insulation coating can effectively improve the outdoor insulation capacity of vacuum arc extinguishing, which puts forward higher requirements for the airtightness and vacuum bellows of switchgear. The development of vacuum switches towards higher voltage levels and the increased rated current have put forward higher requirements for heat dissipation and X-ray shielding in vacuum interrupters. Previous studies have shown horseshoe-type longitudinal magnetic contacts have good thermal flow capacity. The commercial single break vacuum arc extinguishing chamber has developed to 145 kV/40 kA, and the development trend of vacuum breaking environmentally friendly power switchgear has been summarized based on existing products. Based on the current research status, further research focuses on the development of environmentally friendly high-voltage power switchgear towards higher voltage levels were summarized, including the decomposition characteristics of environmentally friendly gases under different fault conditions and the relationship between their decomposition products and insulation arc extinguishing performance, magnetic control technology for large diameter and large distance vacuum arcs, optimization design of insulation coordination for vacuum breaking environmentally friendly power switchgear, and control of vacuum arc extinguishing room temperature rise under high current, intended to provide a reference for the future development of SF₆-free eco-friendly power switchgear.