AIS CT Design Innovation Solution Enhancing Measurement Accuracy and Mechanical Stability

​

Challenge Objective:​​ Address the pain points of conventional Air Insulated Switchgear (AIS) Current Transformers (CTs) regarding measurement accuracy (especially under overload and transient conditions), mechanical stability, and long-term reliability. Achieve core technological innovation to comprehensively enhance product performance.

​Core Technology Optimization Solutions:​​

1. ​Ring Core Material Revolution: Nanocrystalline Alloy Replaces Silicon Steel​
• ​Core Solution:​​ Abandon traditional silicon steel, adopting high-performance iron-based Nanocrystalline Alloy as the core material.
• ​Technical Advantages:​​
• ​Ultra-low Core Loss (≤0.5W/kg):​​ Significantly reduces hysteresis and eddy current losses compared to silicon steel, markedly decreasing heat generation and improving energy efficiency.
• ​Ultra-high Saturation Flux Density (1.8T):​​ Far exceeds the saturation point of silicon steel (typically <1.6T), significantly enhancing anti-saturation capability.
• ​Guaranteed Precision:​​ Maintains stable operation in the linear region even under 120% rated current overload conditions, ensuring sustained fulfillment of stringent 0.2S class accuracy requirements.
• ​Broad Frequency Response:​​ Excellent high-frequency characteristics lay the foundation for precise transient current measurement.
2. ​Anti-Vibration Structural Design: Rigid-Flex Composite Encapsulation​
• ​Core Solution:​​ Employ integral vacuum casting and curing of secondary windings and key leads using a high-toughness epoxy resin + directionally reinforced glass fiber composite material.
• ​Technical Advantages:​​
• ​Exceptional Mechanical Stability:​​ Forms a high-strength, high-rigidity monolithic structure, effectively absorbing and dispersing mechanical stress and vibration energy.
• ​Vibration Resistance Proven:​​ Passed stringent broad-band random vibration sweep testing (10-500Hz, simulating harsh conditions), with measured displacement <0.1mm, well below standard limits. Eliminates risks of secondary terminal loosening and solder joint fatigue fracture caused by vibration.
• ​Environmental Tolerance:​​ Excellent resistance to weather, moisture, and dust, protecting against harsh operating environments.
3. ​Distributed Air Gap Technology: Precision Remanence Management​
• ​Core Solution:​​ Precisely introduce a series of micron-level (~50µm) distributed and controlled air gaps into non-critical magnetic path regions of the core via a specialized process.
• ​Technical Advantages:​​
• ​Effective Remanence Control:​​ Efficiently limits residual flux (remanence) generated in the core after fault current interruption, significantly reducing its impact on subsequent measurement accuracy (especially for small currents).
• ​Transient Performance Leap:​​ Significantly improves the CT's transformation capability for non-periodic decaying DC components (DC Offset) generated by power system faults (e.g., short-circuits), ensuring transient current transformation error <5%. Meets modern smart grid requirements for high transient accuracy in protection CTs (incorporating aspects of TP-class CT characteristics).
• ​Maintained High Accuracy:​​ Preserves core integrity in critical magnetic path regions, ensuring high-precision measurement (Class 0.2S) under normal operating currents.

​Comprehensive Benefits (Quantifiable Value):​​

• ​Measurement Accuracy Assurance:​​ Consistently achieves Class 0.2S accuracy requirements under demanding conditions (e.g., 120% overload, complex transients), providing more reliable "eyes" for energy metering and protection systems.
• ​Reliability Leap:​​ Significant reduction in failure rate ≥60%. Mechanical failures caused by vibration are virtually eliminated. Core material and structural upgrades substantially enhance overall stability.
• ​Extended Service Life:​​ Optimized design significantly reduces impacts from material aging, stress fatigue, and thermal effects, increasing projected overall lifespan to ≥40 years, dramatically reducing lifecycle maintenance and replacement costs.
• ​Power System Security Foundation:​​ High-accuracy transient transformation capability is crucial for ensuring rapid and accurate fault clearing by protection relays, strongly supporting secure and stable grid operation.

​Implementation & Validation:​​
The core technologies of this solution (Nanocrystalline Core, Anti-Vibration Composite Encapsulation, Distributed Micro Air Gaps) have been rigorously validated through type testing, environmental testing (temperature rise, humidity, condensation), and long-term accelerated aging tests. Vibration testing strictly adhered to standards including IEC 60068-2-6. Electromagnetic performance tests (accuracy, transient characteristics, temperature rise, insulation, etc.) were conducted in accordance with IEC 61869-1, -2, and relevant national standards. Test report data robustly supports the solution's efficacy.