SEL-351S

Protection System

The SEL-351S is an advanced protection system designed for the protection, monitoring, and control of distribution feeders. It integrates comprehensive protection functions with precise monitoring, control, and fault locating into a single package. With its vast array of protection elements and flexible control logic, it reliably protects lines and equipment in both radial and looped networks and includes advanced power quality analysis capabilities.

Key Features

Comprehensive Overcurrent Protection

Provides phase, negative-sequence, residual-ground, and neutral-ground overcurrent elements with directional control to optimize protection for diverse network configurations.
Load-Encroachment Logic

Accurately distinguishes between heavy load conditions and actual three-phase faults, preventing nuisance tripping and enhancing the security of the protection system.
Advanced Breaker Failure Protection

Features built-in high-speed breaker failure elements and native logic to quickly prevent the escalation of system faults.
Second-Harmonic Blocking

Detects magnetizing inrush current during transformer energization to prevent the relay from tripping unnecessarily.
Power Quality Monitoring (VSSI)

Provides Voltage Sag, Swell, and Interruption (VSSI) reports to help troubleshoot and analyze local power quality disturbances.
Communications-Assisted Trip Logic

Utilizes built-in logic for fast tripping, which reduces fault duration and minimizes damage to system loads and power equipment.
Accurate Fault Locator

Pinpoints fault locations precisely, allowing line crews to respond faster and significantly reducing outage times.
Synchrophasors

Supports the IEEE C37.118 standard to provide real-time data for wide-area monitoring and detailed post-event analysis.

Large Operator Interface

Designed with large, easy-to-use buttons and a clear display to maximize operational convenience directly in the field.
SafeLock® Trip/Close Pushbuttons

Optional independent pushbuttons feature high-visibility LEDs that clearly indicate breaker status and facilitate secure local control.
Front-Panel USB Port

Allows for quick and easy connection to a laptop for transferring settings and diagnostic data without the need for special converters.
Built-in Web Server

Enables users to monitor relay status, view metering data, and access event records via a standard web browser over an Ethernet network.
Extensive Protocol Support

Compatible with a wide range of industry standards, including SEL, IEC 61850 (optional), DNP3, Modbus, ASCII, FTP, Telnet, and PRP.
Enhanced Breaker Monitoring

Continuously tracks breaker status and contact wear, providing data that helps operators schedule maintenance more efficiently.
Flexible Hardware Options

Offers various power supply ranges and communication port configurations (Ethernet, Serial, Fiber-optic) to meet specific installation requirements.

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