Protection & Control

SEL-787-2/-3/-4 Transformer Protection Relay

Safeguard and monitor a wide range of two-, three-, and four-winding transformers with the SEL-787 platform.

This solution offers advanced automation, flexibility, asset management data, and seamless retrofitting of most electromechanical relays. The optional 5-inch touchscreen display enables direct setting, monitoring, and control of your system, including up to five, two- or three-position, disconnect switches

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SEL-487B Bus Differential and Breaker Failure Relay

The relay offers optimized, low-impedance bus differential fault detection through high-speed, subcycle protection combined with high-security operation for external faults.

This solution delivers superior protection performance while integrating station automation features for seamless deployment in new and retrofit applications.

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SEL-487E Transformer Protection Relay

The SEL-487E is designed to protect and monitor transformers, offering up to six three-phase restraint inputs, three independent restricted earth fault (REF) protection elements, and two three-phase voltage inputs. This relay minimizes transformer damage by responding to internal faults in less than 1.5 cycles and helps prevent catastrophic failures by detecting turn-to-turn faults involving as little as 2% of the total winding.

The included software simplifies commissioning by recommending matrix compensation settings, while through-fault and thermal monitoring enable tracking of transformer wear for timely maintenance. Additionally, breaker wear monitoring reduces unnecessary maintenance costs, saving both time and money.

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SEL-351 ProtectionSystem

The SEL-351 Protection System is an ideal solution for directional overcurrent applications, featuring built-in Ethernet and IEEE C37.118 synchrophasors. Optional Mirrored Bits communications and power quality monitoring capabilities provide additional flexibility to meet diverse requirements.

This system has become the protection standard for utility and industrial electrical systems globally.

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SEL-451 Protection, Automation, and Bay Control System

The SEL-451 serves as an integral component of a full substation protection, control, and monitoring system, effectively reducing maintenance costs by accurately tracking breaker operations.

By monitoring interruption times and accumulated breaker duty, it facilitates proactive maintenance decisions. Information can be integrated with SCADA or automation systems via a communications processor or directly through the Ethernet port.

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SEL-751 Feeder Protection Relay

The SEL-751 Feeder Protection Relay is the ideal solution for industrial and utility feeder protection, supporting conventional and low-energy analog (LEA) current and voltage inputs. It offers flexible I/O options, easy mounting, and fast settings as well as it provides full protection for radial and looped distribution circuits, including:

• Arc-flash mitigation
• Fault location
• High-impedance fault detection
• Broken conductor detection
• Event analysis

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SEL-311C Transmission Protection System

This protection system is designed for comprehensive protection, reclosing, monitoring, and control of transmission lines.

Key features include:

• Four-shot recloser
• Patented capacitance voltage transformer (CVT) transient overreach logic to enhance security of Zone 1 distance elements
• Overcurrent elements with directional control, monitoring, and metering.

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SEL-411L Advanced Line Differential Protection, Automation, and Control System

The SEL-411L Transmission Line Relay offers comprehensive protection and control for transmission lines of any length, including short, long, and series-compensated lines.

It provides differential and distance protection with phase- and sequence-based operating elements for enhanced sensitivity and high-speed operation.

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SEL-421 Protection, Automation, and Control System

The SEL-421 Protection, Automation, and Control System is designed for high-speed distance and directional protection, providing complete control for a two-breaker bay.

It protects transmission lines using a combination of five zones of phase and ground-distance elements, along with directional overcurrent elements. The system features a graphical user interface (GUI) that simplifies the implementation of typical line protection schemes.

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SEL-T401L Ultra-High-Speed Line Relay

The SEL-T401L is a high-performance line protective relay in a compact 3U package, that offers exceptional operating speeds and a comprehensive suite of primary and backup protection functions, making it suitable for various applications.

Designed to simplify line protection, this relay features straightforward protection strategies and fewer settings. It can operate independently or integrate into a redundant protection system with other SEL relays, avoiding common-mode failure concerns.

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