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.