Breaking the "Extreme Cold" Barrier: All-Lifecycle Anti-Freezing Solution for 138kV Dead Tank Circuit Breakers Ensures Zero-Fault Operation in -30℃ Grids

Project Overview

Twelve 138kV dead tank circuit breakers at a high-altitude substation in Northern China were long plagued by extreme cold of -30℃, leading to SF6 liquefaction, insulation degradation, and frequent mechanical jamming during operations. In the winter of 2023, one unit suffered a tank fracture and gas leakage due to low temperatures, resulting in a 60-hour power outage and losses exceeding 600,000 RMB. Our company urgently implemented an "All-Lifecycle Comprehensive Anti-Freezing Governance Solution": adopting an SF6/N2 gas mixture (liquefaction point < -40℃), high-toughness steel for the tanks, and a dual-circuit intelligent heat-tracing and temperature/pressure monitoring system. Post-upgrade, the units have operated with zero faults for two consecutive winters in -30℃ conditions, reducing annual O&M costs by 65% and firmly securing the safety of the power grid during extreme cold.

Exceptional Design · Root Cause Eradication

• Dual Upgrade of Media & Materials: The SF6/N2 gas mixture (SF6 ≤50%) prevents liquefaction. The tank is constructed from high-strength steel with a -40℃ impact toughness ≥27J, combined with cold-resistant fluororubber seals to eliminate fracture risks.

• Intelligent Thermal Protection: Features a detachable insulation layer and dual-circuit electric heat tracing (automatic activation below -20℃), keeping internal tank temperatures stable above -10℃. Real-time linkage between temperature and pressure sensors provides early warnings and proactive hazard intervention.

• Precise O&M Empowerment: Dedicated winter pre-season maintenance (replacement of low-temperature lubricants and seal inspections) combined with a modular quick-repair design reduces fault response time to under 2 hours and decreases manual reliance by 75%.

Empowering Infrastructure Development

This solution has been solidified into the "Technical Specifications for Low-Temperature Adaptability of High-Voltage Circuit Breakers in Alpine Regions" and applied at scale across over 40 substations in Inner Mongolia, the Qinghai-Tibet Plateau, and Xinjiang. To date, it has averted 52 low-temperature-related faults and saved over 12 million RMB in annual O&M costs. Through our "Material-Structure-Intelligence" trinity anti-freezing system, we are spearheading a revolution in the environmental adaptability of power equipment, providing a replicable Chinese solution for global alpine grid safety and fulfilling our mission: "Ensuring power reliability, even in extreme environments."