Product/Technical Services

Line Differential Protection GRL100

Product Overview

GRL100 provides high-speed, phase-segregated line differential protection, with communication over dedicated optical fibre links, 64 kbit/s multiplexed communication channels or microwave links.The relay can be applied in various EHV/HV network configurations, including overhead lines or underground cables, two-terminal or three-terminal lines, short or long distance lines. The main protection is supported by a complete range of back-up protections, auto-reclosing with check-synchronising and enhancements such as highly accurate fault location, metering, data recording and communications. A GPS-synchronised model is now available, designed for use over SDH/SONET communication networks in which propagation delays may differ between the send and receive paths.

Technical Description

Protection functions

  1. Phase-segregated line differential protection for use with digital telecommunication systems

  2. Zero-sequence current differential protection for high resistance earth faults

  3. Applicable to various lines
    - Two-terminal or three-terminal lines
    - Overhead lines or underground cables, etc.

  4. Operating time typically 1 cycle

  5. Master/master design

  6. Automatic transmission delay compensation

  7. Charging current compensation

  8. Overcurrent backup protection

  9. Stub fault protection for one-and-a-half breaker scheme

  10. Broken conductor detection

  11. Direct intertripping

  12. Out-of-step protection

  13. Breaker failure protection


Metering and recording functions

  1. Metering
    - Power system voltages, Local and remote terminal currents, differential currents, power, frequency

  2. Recording
    - Event record
    - Fault record
    - Disturbance record

  3. Fault location

  4. Calendar and Time
    - IRIG-B port for external clock

Autoreclose functions

  1. Single-shot autoreclose
    - single-phase / three-phase / single- and three-phase autoreclose
    - Multi-phase autoreclose for double circuit line

  2. Multi-shot autoreclose
    - three-phase autoreclose

Menu-driven human interfaces

  1. Liquid Crystal Display (LCD) display with operation keys
    - Relay setting and data display

  2. Personal computer (PC) interface
    - Relay setting
    - Recorded data display
    - Waveform analyzing

Automatic supervision

  1. Automatic monitor

Fault detector (Option)

  1. Serial redundancy for tripping