This Line Protection and Control Intelligent Electronic Device (IED) is designed to provide comprehensive protection, control, and monitoring for overhead transmission lines and underground cable feeders across all voltage levels, from distribution networks to extra-high-voltage transmission systems. The IED combines high-speed line differential protection, distance protection, automatic reclosing, backup protection, and bay control into a single integrated platform, making it suitable for both conventional and complex power system applications.

Key Features
Phase-segregated current differential protection
Full-scheme distance protection
Protection for overhead lines and underground cables
Support for heavily loaded transmission lines
Multi-terminal line protection
Single-, two-, and three-phase tripping
Automatic reclosing with synchronism check
High-impedance differential protection for special applications
Integrated bay control and interlocking
IEEE C37.94 communication interface
Redundant communication support
Multiple backup protection functions
Wide Application Range

The IED is suitable for protecting a broad range of power system assets, including:

Overhead transmission lines
Underground cable feeders
Heavily loaded transmission circuits
Multi-terminal transmission lines
Generator block transformer cable connections
Utility transmission networks
Industrial power systems

Its flexible design allows deployment from medium-voltage distribution systems through the highest transmission voltage levels.

Phase-Segregated Current Differential Protection

The primary protection function is phase-segregated current differential protection, which delivers fast, selective fault detection by comparing current measurements from all protected line terminals.

Key advantages include:

High sensitivity to high-resistance faults
Secure phase selection
Excellent stability during external faults
Fast operating time
Reliable operation under heavy loading conditions

The relay provides six stabilized current inputs per phase, allowing protection of:

Multi-breaker substations in three-terminal line applications
Up to five-terminal transmission lines with single-breaker arrangements

This flexibility makes the IED suitable for complex transmission network topologies.

Communication System

Differential protection communication between line terminals is based on the IEEE C37.94 fiber-optic communication standard, ensuring dependable high-speed exchange of differential current information.

For applications requiring enhanced availability, communication channels can be duplicated to provide full communication redundancy.

Additional communication capabilities include:

Eight dedicated channels for intertrip signaling
Binary signal exchange between line terminals
Support for redundant communication architectures

These features improve protection reliability in mission-critical installations.

Charging Current Compensation

Integrated charging current compensation improves differential protection sensitivity on:

Long overhead transmission lines
Long underground cable circuits

By compensating for line charging current, the protection maintains dependable operation while minimizing the risk of false differential current measurements.

Full-Scheme Distance Protection

The IED includes independent full-scheme distance protection, operating in parallel with the line differential protection.

This function provides:

Complete transmission line protection if the differential communication channel fails
Remote-end backup protection
Independent second main protection scheme when using a separate communication channel
Full line coverage under all operating conditions

This redundant protection philosophy significantly improves overall system dependability.

High-Impedance Differential Protection

An optional high-impedance differential protection function is available for specialized applications, including:

Tee-connected feeders (T-feeders)
Line reactors

This function provides highly selective protection for equipment not ideally suited to conventional differential protection methods.

Automatic Reclosing

The integrated automatic reclosing function supports:

Single-phase reclosing
Two-phase reclosing
Three-phase reclosing
Priority logic for multi-breaker switchgear arrangements

The autoreclosing function coordinates with the synchronism check feature to ensure that circuit breakers are reclosed only under acceptable synchronization conditions.

Both high-speed and delayed reclosing modes are supported to meet various system requirements.

Backup Protection Functions
capabilities.

Recommended other models：