The acceleration of global environmental upgrading and energy transformation is driving the green transformation of power equipment. With the joint efforts of power grid users and various manufacturers, the environmental protection scheme of the circuit breaker function unit of the ring main unit has been widely used in the power grid. However, as the switch equipment at the end of the distribution network, the ring main unit is difficult to meet the needs of various users in different usage scenarios with a single circuit breaker solution, and it will also increase customers' investment expenses. Continuously improving various application functional units of the ring main unit is of great significance for promoting environmentally friendly ring main units among various users.
Innovative breakthrough of ABB compressed air load switch
In the field of power equipment, SF6 (sulfur hexafluoride) gas has long dominated due to its excellent insulation and arc extinguishing performance, but its greenhouse effect potential is as high as 24300 times that of CO ₂, making it a major challenge in the global carbon reduction process. The load switch scheme is widely used in the use of ring main units. Mature SF6 based load switches use SF6 as the insulation and breaking medium, with mature technology and cost-effectiveness.
Faced with the industry dilemma of "environmental friendliness, economy, and high performance", ABB has innovatively launched the 12kV Safe Air compressed environmentally friendly gas load switch ring network unit, filling the gap in the field of economical environmental protection solutions for medium voltage ring network equipment and providing an innovative path that combines technical feasibility and economy for the green upgrade of the power grid.
ABB's compressed air load switch adopts an innovative compressed air arc extinguishing structure, which continues the spring operated mechanism that has been validated in the market for more than 20 years, ensuring the stability and reliability of the equipment. Its transmission chain strength meets the new standard GB1985-2023, and adopts a highly reliable electric field design to ensure its mechanical and electrical performance. This product can be flexibly combined with circuit breaker cabinets that meet the standardization specifications of State Grid, and supports flexible shared box solutions, enabling it to meet various application scenarios and usage standards. In addition, the equipment also has flexible expansion methods, allowing for top or side expansion, and is compatible with ABB's Safe Digital digital solution for ring main units, further enhancing the level of intelligence.
Three core technological breakthroughs: the environmentally friendly and efficient way of ABB compressed air environmentally friendly gas load switch
1. Compressed arc extinguishing technology
The arc extinguishing device of ABB's compressed air load switch consists of dynamic and static main contacts, arc contacts, and pistons. Its working principle is to use the overpressure generated by the compressed gas of the piston to "blow out" the arc and disconnect the load current. When the pressure switch is closed, arc pre breakdown occurs at the arc contact. During the opening and closing process, the arc is also ignited at the arc contact, and the arc effect of the entire closing and opening process is concentrated on the arc contact, reducing the loss of the main contact, extending the maintenance cycle of the equipment, and improving the service life and stability of the equipment. Moreover, compared with the vacuum bubble series or parallel disconnection technology, the pressure type arc extinguishing technology has a simpler and more stable contact structure.
The opening and closing process of the pressure switch:
1) The main contact is completely closed.
2) The moving contact moves downwards and compresses the gas.
3) The moving contact separates first, and the arc contact separates later to generate an arc, while driving the compressed gas to flow towards the arc area.
4) The gas flows towards the arc area and flows out in both directions from the arc area, quickly extinguishing the arc.
5) The arc is cut off, and both the moving contact and the arc contact are separated.
The compressed air technology has been widely used in high-voltage circuit breakers. ABB has innovatively applied the compressed air arc extinguishing system to 12kV load switch units, overcoming the performance bottleneck of dry air media and filling the industry gap in this field.
2. The "stationary point" design of the pressure switch and the "precise braking point" for safe power-off
The "stationary" principle of ABB compressed air load switch achieves efficient arc extinguishing through precise control of the synergistic effect of airflow and mechanical action. The core lies in utilizing the gas dynamic characteristics to form a local high-pressure zone, and the specific process is as follows:
When the switch is opened, the moving contact drives the piston to compress the insulating gas in the arc extinguishing chamber, generating high-speed airflow to blow towards the arc. During the process of contact separation, as the displacement of the moving contact causes a sudden change in the cross-sectional area of the airflow channel, the high-speed airflow velocity drops sharply to zero, and kinetic energy is instantly converted into pressure energy, forming a "stagnation point" with zero gas flow velocity. The local high voltage generated at this time has a dual effect: on the one hand, it compresses the arc diameter through the "thermal contraction effect" and increases the arc resistance; On the other hand, the increase in high-pressure gas density significantly enhances the insulation strength of the medium, effectively suppressing arc reignition.
This design creates better arc extinguishing conditions during the contact separation process through precise coordination of mechanical motion and airflow dynamics. Like a precise 'pneumatic brake', it not only avoids insufficient airflow energy caused by too fast movement, but also prevents the arc from continuing to burn due to too slow movement. This dynamic balance ensures that the arc can be extinguished and improves the breaking ability of the switch.
3. The dual advantages of environmental protection and economy
ABB's compressed air load switch uses dry air instead of SF6, which has an extremely low leakage rate (≤ 0.01%) and effectively reduces the impact on the environment. This switch uses dry air as the insulation medium, which is composed of 19.5-23.5% oxygen and residual nitrogen, ensuring that it will not cause any harm to the environment throughout the entire product lifecycle. While ensuring equipment performance, the compressed air load switch adopts a simpler and more efficient structure and design, with higher cost-effectiveness.
Addressing industry pain points and supporting green electricity
Against the backdrop of accelerating global green transformation, ABB will continue to innovate environmentally friendly power technologies and launch environmentally friendly products that are suitable for various application scenarios such as new energy power stations, smart grids, and industrial parks. In the future, we will provide more efficient green solutions to help the power industry achieve sustainable development goals. ABB is committed to using innovative technology to drive the global energy structure towards a clean transformation and contribute to building a green future.