html{display:none} Hydropower | Schweitzer Engineering Laboratories


Whether it’s a full-plant system or a standalone device, an SEL solution can help you meet the highest standards for reliability and security—while also reducing lifetime cost of ownership.

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With an SEL solution, you can:

  • Standardize on a single relay model to protect your entire fleet. SEL products support the full range of hydro generation sizes, configurations, and voltages.
  • Reduce errors and training costs. Use two identical SEL relays, or combine two different SEL relay models, and achieve high-quality primary and backup protection from a single vendor.

Use SEL products for:

  • Monitoring and control of generator-to-substation connections.
  • Generator and step-up transformer protection—either standalone or combined.
  • Integration into Ethernet-based plant control systems using IEC 61850 Edition 2, DNP3, EtherNet/IP, or Modbus TCP.
  • Annunciation, precise time, and equipment monitoring systems.

Generator Protection

Utility and Continuous Generation Solutions

Protect and control entire generation units—including step-up transformers—with a solution based on the SEL-400G Advanced Generator Protection System or the SEL-700G Generator Protection Relay.


SEL-400G Advanced Generator Protection System

Advanced protection for generators, generator buses, and generator step-up (GSU) transformers, all in one package. Automatically synchronize frequency, voltage, and phase control. Detect faults faster, limit generator damage, and return to service faster.

  • Pumped storage protection—no need for additional relays
  • Comprehensive stator fault protection
  • Injection-based rotor/field winding protection (SEL-400G plus SEL-2664S Stator Ground Protection Relay and SEL-2664 Field Ground Module)
  • Synchronization to the grid
  • Metering and reporting
700G new

SEL-700G Generator Protection Relay

Reliable, comprehensive protection for generators of any size. The SEL-700G is a complete protection and synchronization solution with flexible I/O, advanced communications capabilities, and a variety of mounting options. It is ideal for upgrades and retrofits.

  • Current differential protection
  • Breaker wear monitoring
  • Islanding detection
  • Synchronization to the grid

Metering and reporting functions


SEL-2664S Stator Ground Protection Relay

Protect high-impedance grounded generators from ground faults at standstill, during startup, and while running.


SEL-2664 Field Ground Module

Measure field-to-ground resistance before the generator starts rotating, and continuously monitor operations to protect the field from excessive insulation stress.


SEL-2600 RTD Module

Measure and transmit data from up to 12 resistance temperature detectors (RTDs), and send data back to a compatible device via a fiber-optic cable.

Standby and Prime Generation

SEL offers protective relays perfectly suited for standby and prime generators. They can provide complete standalone protection and are ready to integrate with plant control systems.

700G new

SEL-700G Generator Protection Relay

Reliable, comprehensive protection for generators of any configuration or fuel type. The SEL-700G is a complete protection and synchronization solution with flexible I/O, advanced communications capabilities, and a variety of mounting options.

Monitoring, Control, and Integration

Communicate the relay status, stator temperature, and bearing temperature to the plant control system with SEL products.


SEL-2240 Axion

Remote data acquisition in a rugged, modular platform. Choose versions with 4 or 10 slots, and mix and match the modules to fit your application. Each Axion becomes a node in your plant control network, sending deterministic fiber-optic communications to remote terminal units (RTUs), relays, or programmable logic controllers (PLCs).


SEL-3555 Real-Time Automation Controller (RTAC)

Our most powerful automation controller—a powerful and flexible controller built for automation and integration of protection systems, both large and small.


SEL-735 Power Quality and Revenue Meter

Optimize your system by analyzing data, identifying usage trends, and diagnosing system problems. Capture rate-based demand and energy consumption, and apply time-of-use metering.


SEL-2488 Satellite-Synchronized Network Clock

Receive Global Navigation Satellite System (GNSS) time signals, and distribute precise time via multiple output protocols, including IRIG-B and the Network Time Protocol (NTP).


SEL-2523 Annunciator Panel

Annunciation of alarms and system events—plus programmable logic, communications support, a Sequence of Events recorder, and a software HMI.


SEL-2600 RTD Module

Measure and transmit data from up to 12 RTDs, and send data back to a compatible device over a fiber-optic cable.

Communications and Cybersecurity

SEL communications solutions help ensure that communications networks are reliable, cybersecure, and compliant with NERC CIP auditing requirements.


SEL ICON Integrated Communications Optical Network

A wide-area networking multiplexer optimized for utility and industrial applications. The ICON is configurable for SONET or Ethernet transport. It is also ideal for migrating legacy network technologies to a converged network solution.


SEL-2730M Managed 24-Port Ethernet Switch

Ethernet connectivity and secure network management for SCADA, engineering access, and control.


SEL-2740S Software-Defined Network Switch

The industry’s first field-hardened software-defined networking (SDN)-enabled switch. Centralized, software-controlled traffic engineering puts you in control of your communications flows and helps secure the cyber and physical interfaces.


SEL Flow Auditor Software

Streamline data collection for NERC CIP-007-6 R1 audit reporting. Collect network configurations from the SEL-5056 Software-Defined Network Flow Controller in minutes, without the need for network scanning.

3360 Family


A hardened computing platform with error-correcting code (ECC) memory technology and no moving parts, the SEL-3360 is tested to the same standards as our protective relays and has ten times the mean time between failures (MTBF) of typical industrial computers, making it the perfect platform for the SEL Flow Auditor Software.


SEL-3620 Ethernet Security Gateway

Enhanced security for your control systems and critical cyber assets. A router, VPN endpoint, and firewall device all in one, the SEL-3620 supports secure remote access, multifactor authentication, password management, and more.

Products and Service You Can Rely On

SEL products are designed and manufactured for the world’s most challenging environments, exceeding all industry standards for temperature, shock, and electric stress. An optional conformal coating for circuit boards adds an extra level of protection against contaminants in extreme environments.

Every SEL product comes with a ten-year warranty—the best in the industry. If any product fails under warranty, we’ll repair or replace it for free.

Questions? Contact Us!

We’re happy to answer all your questions and help develop the best solution for your needs.

Contact Engineering Services


Unbeatable Support

SEL support teams are stationed in regional offices around the world and staffed with application engineers who are experts in our products and in power system applications.

Technical support for SEL-manufactured devices is always free. No matter how often you need to call or how long your SEL products have been in service, you’ll reach an SEL expert who can provide the service and support you need.

Our cybersecurity team is always ready with the information and resources needed to keep your OT networks and critical systems secure and working effectively. Cyber services support contracts can include incident response, audits, system hardening, and more, depending on your anticipated needs.