Cost-Efficient & Agile Outdoor Monitoring: The Hybrid Optical/Electric CT Solution

The Challenge:​​ Outdoor high-voltage installations and grid upgrades often demand reliable current monitoring but face significant hurdles: stringent budget limitations, the prohibitive cost and downtime of interrupting live conductors for installation, and the need for flexibility to adapt to temporary sites or evolving infrastructure.

​The Solution: Hybrid Optical/Electric Outdoor Current Transformers using Rogowski Coils.​​ This innovative approach bridges the gap between cost-effectiveness and high performance by strategically combining technologies.

​Core Idea:​​ Integrating lightweight, flexible Rogowski coils as the primary sensor with an integrated module providing traditional (analog) current outputs and the option for fiber-optic digital outputs.

Key Features & Advantages Driving Value

1. ​Unmatched Installation Flexibility (Split-Core Design):​​
• ​No Conductor Shutdown:​​ The flexible Rogowski coil core simply opens and clicks around an energized conductor. This eliminates the major cost and logistical nightmare associated with de-energizing lines or busbars required for traditional solid-core CTs.
• ​Rapid Deployment:​​ Installation is fast and safe, significantly reducing labor time and cost compared to conventional solutions. Ideal for projects with tight schedules.
• ​Versatility:​​ Easily adapts to conductors of various sizes and awkward locations. Perfect for crowded substations, mobile applications, or temporary monitoring points.
2. ​Significant Cost Savings:​​
• ​Reduced Material Costs:​​ Rogowski coils eliminate the expensive iron core, laminated steel, and complex mechanical housing needed in solid-core CTs. Manufacturing is inherently less costly.
• ​Lighter Weight:​​ Substantially reduces shipping and handling costs compared to bulky conventional outdoor CTs.
• ​Simplified Logistics:​​ The flexible core design minimizes risk of damage during transit and storage.
3. ​Superior Performance:​​
• ​High Dynamic Range & No Saturation:​​ Lacking an iron core, Rogowski coils are immune to magnetic saturation. They accurately measure currents ranging from very low loads to extremely high fault currents without distortion, providing reliable data for both metering and protection applications.
• ​Wide Frequency Response:​​ Excellent for measuring complex waveforms and harmonics prevalent in modern grids with renewable integration.
4. ​EMI Immunity & Signal Integrity (Optional Fiber Outputs):​​
• ​Hybrid Output Flexibility:​​ The system provides standard analog outputs (e.g., 1A/5A) compatible with existing protection relays and SCADA. ​Crucially, it offers an optional fiber-optic output channel.​​
• ​Complete EMI Immunity:​​ Fiber-optic transmission is impervious to electromagnetic interference, lightning strikes, and ground potential differences, ensuring critical data integrity in harsh substation environments or over long distances.
• ​Enhanced Safety:​​ Fiber isolation eliminates the risk of dangerous overvoltages propagating from the primary circuit back to secondary equipment via copper wiring.

Ideal Use Cases

This hybrid solution shines in scenarios demanding quick deployment, cost control, and adaptability:

1. ​Temporary Monitoring Installations:​​ Commissioning, load studies, fault location, power quality surveys, or monitoring during planned outages. Easy installation/removal maximizes value for short-term needs.
2. ​Grid Upgrades & Modernization Projects:​​ Quickly adding monitoring points during staged grid expansions, substation upgrades, or feeder reconfigurations without requiring complex shutdowns.
3. ​Dual-Purpose Applications:​​ Where both standard analog inputs (for protection relays) and high-integrity digital metering (for revenue accuracy or critical data) are required in the same location.
4. ​EMI-Sensitive Environments:​​ Sites with heavy switching transients or dense cabling where reliable digital data transmission is paramount.
5. ​Retrofit Applications:​​ Adding monitoring to existing switchgear where access for installing solid-core CTs is restricted or shutdowns are unacceptable.