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World’s First 550 kV Fast SF6 Circuit Breaker for UHV Converter Transformer Explosion Protection
Release time:
2026-07-17
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550 kV fast SF6 circuit breaker for UHV converter transformer explosion protection, has successfully passed technical appraisal by the China Electrotechnical Society (CSEE). The project is a key research achievement under the State Grid Corporation of China (SGCC) framework program led by the China Electric Power Research Institute (CEPRI). Jointly developed by Taikai in collaboration with leading research institutes and universities under the guidance of Academician Chen Weijiang, the technology was recognized by the appraisal committee as the world's first solution of its kind, featuring completely independent intellectual property rights and achieving an internationally leading technical level.
Preventing converter transformer explosions and fires is vital for UHVDC reliability. Conventional circuit breakers typically require 30–50 ms to complete fault interruption. This response time is often insufficient to isolate internal transformer faults, limiting their effectiveness in preventing catastrophic failures. To address this challenge, Taikai assembled a joint R&D team that leveraged its extensive expertise in high-voltage switching technology to develop and validate a new-generation 550 kV fast circuit breaker from concept and design through testing to engineering application.
Technical Highlights
The breaker adopts a proprietary three-break series puffer-type arc-extinguishing chamber configuration, which substantially reduces arcing duration and improves short-circuit breaking margin. Its closing resistor is arranged in a fully independent segmented gas compartment, achieving complete physical isolation between the main breaking gas compartment and the resistor gas compartment to eliminate mutual insulation interference. The 1500 Ω resistor discs are arranged in a delta configuration, extending the resistor switching-in duration, and significantly optimizing the system excitation inrush current suppression effect.
The R&D team has overcome multiple industry-leading core technical challenges, including electromagnetic repulsion hybrid fast tripping mechanism, high-speed actuation of hydraulic spring operating mechanism, high-strength lightweight transmission structure, and ultra-short arcing high-capacity short-circuit breaking technology. It has passed full insulation performance tests after 5,000 continuous operating cycles and maintains full compatibility with the installation dimensions and electrical parameters of conventional 550 kV circuit breakers. Equipped with a modular dual-redundancy control system and three-out-of-two voting relay protection configuration, the equipment reduces system fault clearing time by approximately 50%, providing reliable active explosion and fire protection for UHV converter transformers.
Field Application
Eight sets of Taikai's 550 kV fast SF₆ circuit breakers have been officially put into service at the Dongping Converter Station of the ±800 kV Longdong–Shandong UHV DC Transmission Project. The equipment has maintained stable grid operation for one year since commissioning in May 2025, fully validating its excellent operational reliability and environmental adaptability. This breakthrough breaks the decades-long technical bottleneck restricting the fast fault-breaking capability of conventional SF₆ circuit breakers, representing a key technological leap in China's independent R&D and manufacturing capacity for high-end UHV power transmission and transformation equipment.
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In recent years, Taikai has achieved a series of innovative technological breakthroughs in core products including 252 kV/550 kV/800 kV fast SF₆ circuit breakers and 550 kV explosion-proof bypass trigger gaps. Moving forward, the company will continue to increase R&D investment, accelerate technological iteration and product upgrading, and contribute high-reliability high-voltage power equipment solutions to the construction of new-type power systems.
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