Gas Insulated Switchgear Ultra-Low Temperature Self-Heating Current Transformer Solution

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​Subject: Ultra-Low Temperature Self-Heating CT Solution​

In harsh extreme cold environments (e.g., Siberian oil/gas fields, Antarctic research stations), conventional GIS current transformers (CTs) face critical failures such as material embrittlement, drastic accuracy loss, and sealing failure. This solution is specifically engineered for operations below -60°C, integrating advanced material science, precision temperature control technology, and aerospace-grade sealing processes to ensure long-term reliability and measurement accuracy of GIS systems under extreme low temperatures.

​Core Challenges & Technological Breakthroughs​

1. ​Innovative Cryogenic-Tolerant Materials​
   Coil Frame:​​ Replaced epoxy resin (prone to low-temperature cracking) with polyimide (PI) as the core frame material. Its exceptional temperature tolerance (-269°C to 260°C) maintains superior mechanical strength and dimensional stability under extreme cold, providing rigid coil support to prevent deformation.
   ​Insulation Medium:​​ SF₆ gas within GIS remains physically stable at ultra-low temperatures. This CT design ensures full compatibility with SF₆.
2. ​Active Precision Self-Heating Temperature Control System​
   ​Integrated Heating Element:​​ Nano-carbon heating films are precision-embedded between coil winding layers. This material features an excellent resistance temperature coefficient (0.0035/°C), enabling self-regulating heating characteristics (PTC effect).
   ​Intelligent Temperature Control:​​ The system automatically activates heating when ambient temperature drops to -50°C. Nano-carbon films efficiently and uniformly heat the CT’s core internal components (windings and core), maintaining them within the optimal operating range of -20°C to 0°C. This temperature significantly exceeds material embrittlement thresholds, ensuring stable electromagnetic performance.
3. ​Aerospace-Grade Sealing & Protection​
   Dual Dynamic Seals:​​ Nitrile rubber (NBR) O-rings provide elastic pre-tension force. Groove dimensions are precisely calculated to guarantee effective sealing at -60°C. Core chambers employ full laser welding for hermetic sealing, eliminating leakage risks of traditional seal interfaces.
   Ultra-High Leak Detection:​​ Helium mass spectrometry leak testing ensures overall equipment leakage rates below 1×10⁻⁷ Pa·m³/s (equivalent to molecular-level sealing), effectively blocking external moisture/contaminant ingress and maintaining GIS chamber cleanliness for long-term operation.