Key Benefits

The L90, a member of the UR family of protection relays, is a digital current differential relay system which provides protection for transmission lines. It may be applied on or adjacent to series compensated lines for three phase tripping. The L90 utilizes an innovative current differential scheme with adaptive restraint that allows the relay to operate correctly even when fault currents are distorted by harmonics or CT saturation. Models are available for application on transmission lines with 2 or 3 terminals. The relay may be used as a standalone device or as a component of an automated substation control system.

• High speed single/three pole tripping and reclosing
• Complete support of multiple breaker applications (eg. Ring Bus, Breaker-and-a-half)
• Cost effective and flexible access to information | Multiple communication options and protocols
• Phase segregated dual slope current differential function with adaptive restraint for secure operation
• Increased sensitivity | charging current, and channel asymmetry compensation
• Reduce installation space requirements through compact design | Multifunction device that integrates protection and control functions, programmable pushbuttons and status LEDS, and communication interfaces
• Embedded IEC 61850 Protocol | No external converter required
• 3 zones back-up distance protection
• Customize to specific requirements | Multiple I/O options, programmable logic (FlexLogic™)
• Reduce system event analyzing time and cost | SOE, oscillography, datalogging, IRIG-B time synchronization
• Phasor Measurement Unit | Synchronised phasor information exceeding latest IEEEC37.118 standard
• Enhanced diagnostics continuously verifying the health and correct operating condition of the relay