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 adaptive restraint 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.
Applications
• 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, 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 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
• In-zone power transformer enables savings on CTs and protection device requirements
• 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
• 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
Applications
- Transformer asset monitoring using loss-of-life, aging factor, hottest spot
- Applicable for transformers with up to six windings in a ring bus or breaker-and-a-half configuration
- Reliable and secure protection for three-phase transformers, autotransformers, reactors, split-phase and phase angle regulating transformers
- Stand-alone or component in automated substation control system
Functional Block Diagram
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