Why is the indoor AC high-voltage sulfur hexafluoride ring main unit switchgear particularly suitable for prefabricated substations?
Release Time : 2025-09-17
In modern urban power grid construction, prefabricated substations are widely used in residential areas, commercial centers, industrial parks, rail transit, and other locations due to their compact structure, easy installation, reliable operation, and small footprint. As one of the core components of the medium- and high-voltage distribution systems in prefabricated substations, the indoor AC high-voltage sulfur hexafluoride ring main unit switchgear, with its excellent electrical performance and structural characteristics, has become an indispensable control and protection device for distribution systems 12kV and below. Its unique suitability for prefabricated substations stems primarily from its comprehensive advantages in insulation performance, space utilization, operational reliability, environmental adaptability, and system integration.
Highly integrated and space-saving, it meets the needs of compact designs
Prefabricated substations typically adopt a fully enclosed, modular design, resulting in limited overall space and extremely stringent requirements for the size and layout of internal equipment. The indoor AC high-voltage sulfur hexafluoride ring main unit switchgear uses SF₆ gas as its insulating medium, which has a dielectric strength far greater than that of air. This feature significantly reduces the safe distance between live components within the ring main unit (RMU), enabling equipment miniaturization and high-density integration. Compared to traditional air-insulated switchgear, SF₆ RMUs can be reduced by 30% to 50% while maintaining the same electrical performance. This significantly saves valuable space within the box-type transformer and provides greater flexibility in the layout of transformers, low-voltage switches, and other auxiliary equipment.
Excellent insulation and arc-extinguishing performance ensures safe operation
Sulfur hexafluoride gas not only has excellent insulation capabilities but also possesses exceptional arc-extinguishing properties. During switching operations, when an arc occurs, SF₆ gas quickly absorbs the arc energy and cools the arc path, rapidly extinguishing the arc and effectively preventing arc reignition and overvoltage. This is particularly important for frequently operated ring main power supply systems. Indoor AC high-voltage sulfur hexafluoride ring main unit (RMU) switchgear is typically equipped with a load switch-fuse combination. In the event of a short-circuit fault, the fuse quickly interrupts the fault current, protecting downstream equipment such as the transformer. This "load switch + fuse" protection solution offers a simple structure and reliable operation, making it particularly well-suited for prefabricated substations requiring high reliability and low maintenance.
Sealed design adapts to complex operating environments
Prefabricated substations are often installed outdoors or in semi-outdoor environments, potentially subject to harsh conditions such as high temperature, high humidity, dust, and salt spray. The indoor AC high-voltage sulfur hexafluoride ring main unit switchgear utilizes a fully sealed gas box design, completely enclosing the main circuit conductors, switch components, and SF₆ gas within a stainless steel or aluminum alloy chamber, effectively isolating the device from external environmental influences. This sealed structure not only prevents the intrusion of dust, moisture, and corrosive gases, but also significantly reduces the risk of condensation within the equipment, ensuring stable operation even in humid environments. Furthermore, the high-quality sealing process and long-term stable SF₆ gas pressure significantly extend the maintenance cycle of the ring main unit, typically achieving 10-20 years of maintenance-free service. This makes it ideal for prefabricated substations requiring unmanned or minimal maintenance.
Modular Design for Easy Installation and Expansion
Indoor SF₆ ring main unit (RMU) switches generally adopt a modular structure, allowing for flexible configuration of functional units such as incoming and outgoing lines, interconnectors, and metering systems based on actual power supply needs. During factory prefabrication of prefabricated substations, the RMUs can be preassembled, wired, and commissioned with other equipment, enabling "plug-and-play" operation. This significantly reduces on-site installation and commissioning time and improves project efficiency. Furthermore, the modular design facilitates future expansion or retrofitting by simply adding corresponding functional units without having to replace the entire system, enhancing system scalability and cost-effectiveness.
In summary, the indoor AC high-voltage sulfur hexafluoride ring main unit switchgear, with its compact size, strong insulation performance, excellent arc extinguishing capability, tight sealing, long maintenance-free intervals, and modular design, perfectly meets the compactness, reliability, environmental adaptability, and integration requirements of prefabricated substations. In a ring or radial power supply system with a rated voltage of 12kV and a rated current of 630A or below, it not only undertakes the control and protection tasks of the power system, but is also a key equipment to ensure the efficient, safe and stable operation of prefabricated substations.
Highly integrated and space-saving, it meets the needs of compact designs
Prefabricated substations typically adopt a fully enclosed, modular design, resulting in limited overall space and extremely stringent requirements for the size and layout of internal equipment. The indoor AC high-voltage sulfur hexafluoride ring main unit switchgear uses SF₆ gas as its insulating medium, which has a dielectric strength far greater than that of air. This feature significantly reduces the safe distance between live components within the ring main unit (RMU), enabling equipment miniaturization and high-density integration. Compared to traditional air-insulated switchgear, SF₆ RMUs can be reduced by 30% to 50% while maintaining the same electrical performance. This significantly saves valuable space within the box-type transformer and provides greater flexibility in the layout of transformers, low-voltage switches, and other auxiliary equipment.
Excellent insulation and arc-extinguishing performance ensures safe operation
Sulfur hexafluoride gas not only has excellent insulation capabilities but also possesses exceptional arc-extinguishing properties. During switching operations, when an arc occurs, SF₆ gas quickly absorbs the arc energy and cools the arc path, rapidly extinguishing the arc and effectively preventing arc reignition and overvoltage. This is particularly important for frequently operated ring main power supply systems. Indoor AC high-voltage sulfur hexafluoride ring main unit (RMU) switchgear is typically equipped with a load switch-fuse combination. In the event of a short-circuit fault, the fuse quickly interrupts the fault current, protecting downstream equipment such as the transformer. This "load switch + fuse" protection solution offers a simple structure and reliable operation, making it particularly well-suited for prefabricated substations requiring high reliability and low maintenance.
Sealed design adapts to complex operating environments
Prefabricated substations are often installed outdoors or in semi-outdoor environments, potentially subject to harsh conditions such as high temperature, high humidity, dust, and salt spray. The indoor AC high-voltage sulfur hexafluoride ring main unit switchgear utilizes a fully sealed gas box design, completely enclosing the main circuit conductors, switch components, and SF₆ gas within a stainless steel or aluminum alloy chamber, effectively isolating the device from external environmental influences. This sealed structure not only prevents the intrusion of dust, moisture, and corrosive gases, but also significantly reduces the risk of condensation within the equipment, ensuring stable operation even in humid environments. Furthermore, the high-quality sealing process and long-term stable SF₆ gas pressure significantly extend the maintenance cycle of the ring main unit, typically achieving 10-20 years of maintenance-free service. This makes it ideal for prefabricated substations requiring unmanned or minimal maintenance.
Modular Design for Easy Installation and Expansion
Indoor SF₆ ring main unit (RMU) switches generally adopt a modular structure, allowing for flexible configuration of functional units such as incoming and outgoing lines, interconnectors, and metering systems based on actual power supply needs. During factory prefabrication of prefabricated substations, the RMUs can be preassembled, wired, and commissioned with other equipment, enabling "plug-and-play" operation. This significantly reduces on-site installation and commissioning time and improves project efficiency. Furthermore, the modular design facilitates future expansion or retrofitting by simply adding corresponding functional units without having to replace the entire system, enhancing system scalability and cost-effectiveness.
In summary, the indoor AC high-voltage sulfur hexafluoride ring main unit switchgear, with its compact size, strong insulation performance, excellent arc extinguishing capability, tight sealing, long maintenance-free intervals, and modular design, perfectly meets the compactness, reliability, environmental adaptability, and integration requirements of prefabricated substations. In a ring or radial power supply system with a rated voltage of 12kV and a rated current of 630A or below, it not only undertakes the control and protection tasks of the power system, but is also a key equipment to ensure the efficient, safe and stable operation of prefabricated substations.