The ABB RED670 (Relion 670 series) is a high-performance Intelligent Electronic Device (IED) specifically designed for the line differential protection of overhead lines and cables. It provides exceptionally fast and selective phase-segregated differential protection, making it ideal for transmission networks, multi-terminal lines, and series-compensated circuits.

 

Technical Functionality

The RED670 utilizes a phase-segregated current differential algorithm to detect internal faults by comparing the currents entering and leaving the protected zone. To maintain high-speed communication between line ends, it supports dedicated fiber-optic links or digital communication networks using the IEEE C37.94 standard. The “Guard” functionality refers to its advanced “Charging Current Compensation,” which prevents false tripping caused by the capacitive charging currents inherent in long high-voltage cables.

 

Key Specifications

 

Operational Precautions

• Communication Symmetry: Ensure that the communication delay between line ends is symmetrical; significant jitter or asymmetrical delays can cause a “Differential Current” alarm or an unwanted trip.
• CT Star Point Orientation: Verify that the Current Transformer (CT) star points at both ends of the line are oriented correctly toward the protected zone to ensure the differential calculation remains stable.
• Fiber Cleaning: For direct fiber links, use high-purity optical cleaning kits. Dust on the SFP or LC connectors can lead to “Communication Fail” alarms, effectively disabling the differential protection.

 

Common Questions Q&A

Q: Does the RED670 support distance protection as a backup? A: Yes, the RED670 often comes with integrated full-scheme distance protection (up to 5 zones) to provide a secondary layer of protection if the communication link fails.

Q: Can it protect lines with an in-zone transformer? A: Absolutely. The RED670 includes transformer compensation features that account for phase shifts and transformation ratios within the protected zone.

Recommended Similar Models

1. REL670: A dedicated distance protection IED without the line differential feature.
2. REC670: The matching bay controller for managing breakers and switchgear.
3. RET670: Specialized transformer protection for the same 670 series family.
4. RED650: A more compact line differential relay for standard sub-transmission applications.
5. REB670: High-speed busbar protection for complex substation architectures.

Technical documentation and stock status for the ABB RED670 are available through our current power automation inventory.