GE L30 | Line Differential System

GE L30 | Line Differential System

The L30 is a cost-effective line current differential protection relay intended for sub-transmission and medium voltage lines and cables providing reliable and secure operation even under the worst case power system conditions. The L30 provides secure high-speed fault detection and clearance suitable for three-pole tripping applications. The L30 supports inter-relay communications via direct fiber as well as standard RS422, G.703 and C37.94 telecommunication interfaces. The L30 also provides synchrophasor measurements over Ethernet per IEEE C37.118.


  • Overhead 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
  • Applications requiring three-pole autoreclosing and independent synchrocheck supervision

Key Benefits

  • Proven current differential protection ensures secure high-speed tripping
  • Increased sensitivity through dynamic charging current compensation and communication channel asymmetry compensation
  • Adaptive restraint characteristic provides excellent security against measurement errors including CT saturation
  • In-zone power transformer functionality enables savings on CTs and protection device requirements
  • 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 advanced 1 microsecond time synchronization via LAN with IEEE 1588 support
  • Complete IEC 61850 Process Bus solution provides resource optimization and minimizes total P&C life cycle costs
  • Increase network availability by reducing failover time to zero through IEC 62439-3 "PRP" support
  • CyberSentry™ provides high-end cyber security aligned to industry standards and services (NERC® CIP, AAA, Radius, RBAC, Syslog)
  • Advanced fault and disturbance recording, including internal relay operating signals, eliminating the need for external recording devices

Functional Block Diagram

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