CT and Grounding Switch Magnetic Circuit Reuse Integrated Solution: Enabling Compact GIS Substation Construction

Background​
During urban power grid upgrades, limited land resources present a core challenge. Traditional GIS equipment occupies significant vertical space due to the separate structures of current transformers (CTs) and grounding switches, becoming a bottleneck in substation miniaturization design.

​Solution: Modular Integrated Design​
This solution innovatively deeply integrates CT functionality into the grounding switch operating mechanism, achieving spatial reuse and performance breakthroughs:

• ​Space-Efficient Reuse:​​
• Embedded CT Coil: Removes the traditional standalone CT insulator, embedding high-precision measurement coils directly within the inner cavity structure of the grounding switch's insulated operating rod.
• GIS Enclosure Magnetic Circuit Closure: Breakthrough utilization of the GIS equipment's high-strength metal enclosure itself as the core low-resistance path for CT magnetic flux, forming a complete closed magnetic circuit. Vertical space occupation is significantly reduced.
• ​Precise Magnetic Circuit Compensation:​​
• Dual-C Laminated Silicon Steel: To address potential magnetic field distribution non-uniformity caused by non-axisymmetric equipment structure (estimated linearity deviation ≤5%), the core employs dual-C type 0.23mm high-permeability silicon steel sheet laminated modules.
• Directed Magnetic Flux Guidance: The symmetric C-shaped structure design precisely compensates for magnetic circuit asymmetry, ensuring current measurement linearity deviation remains stable at ≤0.5% under both steady-state and transient conditions (up to 40kA peak), meeting Class 0.2S accuracy requirements.
• ​Contact Synchronization Monitoring:​​
• Dual Hall-Effect Sensor Synchronization: High-sensitivity Hall-effect sensor arrays are embedded at key transmission nodes of the grounding blade's power linkage.
• State Synchronized Output: Real-time collection of the blade's open/close mechanical position status, achieving high-precision time synchronization (timestamp alignment accuracy ≤1ms) with the phase current signal output from the CT.

​Core Scenario Value: Urban Compact GIS Substations​

• ​Spatial Compression Breakthrough:​​ Equipment vertical structure depth reduced by 1.2 meters directly, driving overall substation layout optimization. Average substation footprint successfully reduced by 30% (e.g., 220kV GIS distribution area).
• ​Lifespan Consistency Design:​​ Integrated structure simplifies the transmission chain. CT and grounding switch share core moving parts (e.g., operating rod bearing system). Validated over 10,000 full-capacity open/close operation cycles, achieving synchronized mechanical lifespan targets.
• ​Intelligent O&M Enablement:​​ Highly reliable millisecond-level synchronization of Hall position signals and CT data provides unprecedented device-level data support for analyzing grounding switch operation transient currents and assessing arc reignition risks.

​Summary of Technical Advantages​