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Line monitoring is now available in the SEL-T400L Time-Domain Line Protection, further enhancing the ultra-high-speed relay’s capabilities. This new feature detects, locates, tabulates and alarms for recurring disturbances on the line, including low-energy events and faults. This helps utilities improve line maintenance efforts and costs and can reduce the number of line faults by identifying low-energy precursor events before they become faults.

A simple and intuitive feature that requires no additional software, the line monitor triggers on current traveling waves launched by low-energy fault precursors, such as partial discharge due to a dirty insulator, encroaching vegetation or an incipient cable fault. The line monitor then locates fault precursors with high accuracy, tabulates the precursor events for locations along the line and alarms if the event count exceeds a user-settable alarm threshold at any location. With this information, utilities can reduce line faults by selectively cleaning or replacing insulators, trimming vegetation, improving antigalloping solutions, applying line spacers or improving lightning protection.

The SEL-T400L must use the double-ended traveling-wave-based fault-locating method for the line monitor to be operational. Therefore, either a direct fiber-optic channel or an IEEE C37.94 multiplexed channel is required between the two SEL-T400L relays.

The line monitor, which is also available in the SEL-T401L Ultra-High-Speed Line Relay, is included with all new SEL-T400L purchases and is also available to existing SEL-T400L users via a relay firmware upgrade.

Learn more about the SEL-T400L on the product webpage .