Advanced Line Differential Protection, Automation, and Control System

Apply the SEL-411L for complete protection and control of any transmission line. The SEL-411L provides differential protection with both phase- and sequence-based operating elements for sensitivity and high-speed operation. You can choose from many popular fiber and multiplexed communications options. Distance protection and logic from a complete SEL-421 Protection, Automation, and Control System are included to provide backup protection and integration. Any transmission line (short, long, or series-compensated) can be well-protected with the SEL-411L.

Applications

Line Current Differential Protection—Apply subcycle single- or three-pole line current differential protection with backup distance protection for critical transmission lines using serial or Ethernet for differential communications. Patented generalized Alpha Plane technology combined with overcurrent supervision, external fault detection, and disturbance detection logic enables the 87L function to operate with exceptional security and sensitivity. You can invert individual or grouped CT or PT polarities to account for field wiring or protection zone changes.

Series-Compensated and Long Lines—Prevent Zone 1 overreach on series-compensated lines with optional logic in the SEL-411L-1 Advanced Line Differential Protection, Automation, and Control System. Built-in charging compensation improves the sensitivity and speed of differential protection for long lines.

In-Line Transformers—Simplify protection schemes and reduce equipment costs by providing complete protection for the combined line and transformer. The 87L function of the relay allows in-line transformer applications that compensate for vector group, ratio, and zero sequence of the in-zone transformer. Use harmonic blocking, restraint, or both for stabilization under magnetizing inrush conditions.

Out-of-Step Blocking and Tripping—During power swings, the relay automatically selects either out-of-step blocking or out-of-step tripping. Out-of-step blocking enhances your security by blocking distance elements during stable swing conditions. During unstable power swing conditions, the SEL-411L implements out-of-step tripping to maintain generation load balance.

Multiterminal Transmission Lines—Protect lines with up to four terminals. Apply the SEL-411L on breaker-and-a-half bus configurations or other two-breaker schemes with the relay’s dual CT and PT inputs. Efficiently dispatch line crews to quickly isolate line problems and restore service faster. The multiterminal fault location system quickly locates faults even on lateral transmission lines.

Traveling-Wave Fault Locator—Accurately pinpoint faults with time-synchronized traveling-wave fault location. Save time and money by sending maintenance crews to the tower nearest the fault.

Bay Control, Reclosing, and Breaker Failure Detection—Apply complete bay control, reclosing, and breaker failure protection for two breakers. Monitor circuit breaker performance, including the average and last tripping time, motor run time, and contact-interrupting duty.

Reliable Distance Protection—Provide reliable backup protection with five zones of phase and ground distance elements that include directional overcurrent elements for subcycle operation and security.

Thermal Overload Protection—Use the three independent IEC 60255-149 thermal elements to activate a control action, issue an alarm, or trip when equipment overheats as a result of adverse operating conditions. The SEL-2600 RTD Module can provide ambient temperature measurements.