GE Multilin L90 Line Current Differential System


The L90 provides high-speed current differential protection suitable for transmission lines and cables of various voltage levels while supporting complete distance protection and dual-breaker applications suitable for single and three-pole tripping applications. The L90 uses synchronized sampling at each relay to limit the impact of communications channel issues. The differential element’s balances sensitivity for internal faults and security during external faults. The L90 supports inter-relay protection communications via direct fiber as well as different interfaces.

Key Benefits:

  • Phase-segregated differential protection ensures secure high-speed single-pole tripping
  • High-speed cost-effective five zones quad or mho, phase and ground distance protection with multiple standard and customizable pilot schemes support
  • Reliable and secure protection on lines equipped with series compensation
  • Increased sensitivity through dynamic charging current compensation and communication channel asymmetry compensation
  • Phasor Measurement Unit (synchrophasor) according to IEEE C37.118 (2011) and IEC 61850-90-5 support
  • Three independent fiber or copper Ethernet ports for simultaneous/dedicated network connections with 1 microsecond time synchronization via LAN with IEEE 1588 support
  • CyberSentry™ provides high-end cyber security aligned to industry standards and services (NERC CIP, AAA, Radius, RBAC, Syslog)
  • AAdvanced IEC 61850 Ed. 1 and Ed. 2 certified implementation, complete settings via SCL files and flexible process bus support (IEC 61850-9-2LE or IEC 61850-9-2 Hardfiber) ensures interoperability, device managing optimization and reduced cost of ownership
  • Routable GOOSE (R-GOOSE) enables GOOSE messages going beyond the substation, which enables wide area protection and control applications
  • Application flexibility with multiple I/O options including high density I/O, programmable logic, modularity, and specific customization
  • An integrated large, full color display, provides real-time visualization and control of the protected bay, via a bay mimic as well as annunciator functionality and graphical visualization of phasors
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  • Overhead lines including series-compensated lines and underground cables of different voltage levels
  • Circuits with tapped transformer feeders
  • Suitable for three-terminal line configurations, with channel redundancy and direct transfer tripping (DTT)
  • Wide area system monitoring and control and using integrated protection and synchrophasor measurement
  • Single and dual-breaker circuits requiring single/three-pole autoreclosing and independent synchrocheck supervision
  • Secure application with Capacitively-Coupled Voltage Transformers (CCVTs)


Key Features:

  • Phase-segregated line current differential with adaptive restraint and ground differential, stub bus protection
  • In-zone power transformer enables savings on CTs and protection device requirements
  • Thermal protection, under/over frequency, broken conductor
  • Phase distance (five zones) with independent compensation settings for in-zone power transformers
  • Ground distance (five zones) with independent self and mutual zero- sequence compensation, reverse power
  • Line pickup, reverse power, out-of-step tripping and power swing blocking
  • Thermal overload, phase, neutral and negative sequence directional overcurrent; and broken conductor
  • Over, under and rate of change of frequency, synchronism check for dual-breaker applications




  • Complete IEC 61850 Process Bus solution providing resource optimization and minimizing total P & C life cycle costs
  • Three independent 100Mbps Ethernet ports enable purpose specific LAN support that eliminates latency effect of heavy traffic protocols on mission critical communication services
  • Embedded IEEE 1588 time synch protocol support eliminates dedicated IRIG-B wiring requirements for IEDs
  • Direct I/O secures high-speed exchange of binary data between URs
  • Increase network availability by reducing failover time to zero through IEC62439-3 “PRP” support
  • IEC 61850-9-2LE networked or IEC61850-9-2 Hardfiber process bus support
  • DNP 3.0 (serial & TCP/IP)
  • IEC 60870-5-103 and IEC 60870-5-104
  • Modbus RTU, Modbus TCP/IP
  • HTTP, TFTP, SFTP and MMS file transfer
  • Redundant SNTP and IEEE 1588 for time synchronization
  • PRP as per IEC 62439-3
  • IRC module that combines C37.92 multimode and direct connection singlemode
  • Supports Routable GOOSE (R-GOOSE)


Cyber Security:

  • Password Complexity
  • AAA Server Support (Radius)
  • Role Based Access Control (RBAC)
  • Event Recorder (Syslog for SEM)


Expanded Control:

  • Expanded Bay Controller Capabilities – providing a one box solution
  • Remote voltage phasors enable synchrocheck with remote terminals
  • Added backup protection functions with sensitive reverse power element “32S”
  • Added over/under/rate of change of frequency elements
  • New thermal overload element
  • New broken conductor element
  • Customizable version of the POTT and DCB schemes “POTT1 and DCB1”
  • Neutral directional overcurrent with dual polarity criteria “67N”

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