GE Multilin L30 | Line Current Differential System

GE Multilin L30 Line Current Differential System

Description

The GE Multilin L30 is a high-performance protective relay designed for primary and backup protection of power transmission lines, including those with series compensation. It operates on the current differential principle—constantly comparing the current entering and leaving the protected line section. Under normal conditions, these currents are equal; any significant difference signals a fault within the protected zone, prompting the relay to isolate the fault rapidly and selectively.

As part of GE’s Universal Relay (UR) family, the L30 offers advanced control, monitoring, and communication capabilities, ensuring reliable operation in challenging power system environments. This helps minimize equipment damage during faults and maintains overall system stability.

Key Features

• Current Differential Protection (87L): Provides fast and selective fault detection and clearing, ideal for multi-terminal lines or lines with taps.

• Subcycle Tripping: Detects and clears faults in less than one power system cycle, reducing stress on equipment and improving stability.

• Phase and Ground Overcurrent Protection (50/51, 50N/51N): Comprehensive backup protection against various fault types.

• Distance Protection (21): Adds an extra layer of selective fault isolation based on impedance measurement.

• Directional Overcurrent Protection (67): Ensures operation only for faults in the intended direction.

• Breaker Failure Protection (50BF): Detects failure of breakers to open and initiates backup tripping.

• Power Swing Blocking/Tripping (68/78): Differentiates faults from power swings to avoid nuisance trips during system disturbances.

• High-Speed Communications: Supports protocols like C37.94 and IEC 61850 GOOSE for secure and rapid communication between relays at different line terminals.

• Dual Breaker Control: Manages two circuit breakers per terminal, providing flexible substation configurations.

• Oscillography and Event Recording: Captures detailed fault waveforms and event data for post-fault analysis.

• Self-Monitoring and Diagnostics: Continuously monitors relay health and reports internal issues.

• Flexible I/O: Configurable binary inputs and outputs for custom control applications.

• User-Friendly Interface: Local HMI for control, status display, and settings adjustments.

Typical Specifications

• Rated Voltage: 60–250 V AC/DC (auxiliary power)

• Rated Current: Configurable for 1A or 5A CT secondary connections

• Frequency: 50/60 Hz nominal

• Protection Functions:

• Line Current Differential (87L)

• Phase Distance (21) and Ground Distance (21N)

• Phase Overcurrent (50/51) and Ground Overcurrent (50N/51N)

• Negative Sequence Overcurrent (50Q/51Q)

• Breaker Failure (50BF)

• Power Swing Blocking/Tripping (68/78)

• Weak-End Infeed (WEI)

• Directional Overcurrent (67/67N)

• Under/Over Voltage (27/59)

• Under/Over Frequency (81U/81O)

• Communication Ports:

• Ethernet (RJ45) supporting IEC 61850, Modbus TCP/IP, DNP3 TCP/IP

• Fiber Optic (C37.94, IEC 61850 GOOSE)

• Serial (RS232, RS485 for Modbus RTU, DNP3)

• Digital I/O: Configurable, varies by model

• Accuracy: Meets or exceeds ANSI/IEEE and IEC standards

• Operating Temperature: -40°C to +85°C

• Mounting: Rack-mount or panel-mount options

• Dimensions and Weight: Varies by chassis and configuration

• Compliance: IEC 61850, ANSI/IEEE, UL, CE certified