html{display:none} Generator Protection | Schweitzer Engineering Laboratories

Generator Protection

Generator Protection

Apply SEL generator protection products and avoid expensive equipment damage and failure while maintaining system performance and increasing availability. SEL quality-tested features provide complete primary and backup protection from all types of faults. SEL’s power interconnection, protection, communications, control, and metering equipment is ideally suited for utility-, industrial-, and commercial-scale power generation systems. SEL solutions protect and control base load, peaking, and stand-by generators of every size and fuel type. Our automatic generation control (AGC) and synchrophasor technology give system operators unprecedented diagnostic and control capabilities to maximize power output, stability, efficiency, and reliability.

SEL products and systems protect and control generators and plants that use hydroelectric, coal, gas, geothermal, wind, biofuel, solar, and other energy sources. Upgrade to a proven SEL protection system today, and be confident that your generation system will be working tomorrow.

Request a Follow-Up



Request a Follow-Up

Advantages of an SEL Generator Protection Solution

  • Design a complete generator protection system, including advanced stator, field, and generator step-up (GSU) relaying.
  • Scale your solution across your generation fleet, from reciprocating standby units to large combined cycle plants and from traditional generation to distributed generation.
  • Integrate remote I/O, annunciators, and transformer monitors to increase unit monitoring and display for operators.
  • Select from multiple protocols for integration into plant control and transmission SCADA systems.
  • Employ software-defined networking (SDN) to increase the security and reliability of the control network.
  • Depend on high-quality SEL products, which lead the industry with the highest mean time between failures and include a ten-year, no-hassle warranty.
  • Meet and exceed revenue accuracy standards and monitor power quality by integrating an advanced meter.

Complete SEL Generator Protection Solution

Combustion Gen System-01

Protection and Integration Components


SEL-400G Advanced Generator Protection System

The SEL-400G offers primary and backup protection for generators of all sizes and types, including hydro, pumped-storage hydro, steam turbine, and combustion gas turbine generators.


SEL-700G Generator Protection Relay

The SEL-700G is the right solution for utility and industrial generator protection, with an autosynchronizer, flexible I/O, and advanced communications. Apply the SEL-700G for comprehensive primary and backup generator protection.


SEL-2664S Stator Ground Protection Relay

Protect high-impedance grounded generators from ground faults at standstill, during startup, and while running by using the multisine frequency injection and neutral overvoltage-based protection in the SEL-2664S.


SEL-2664 Field Ground Module

Add the SEL-2664 to the SEL-300G or SEL-700G to protect all the critical components in your generator with one comprehensive relay. Add the SEL-2664 to the SEL-2664S for complete ground fault protection on both the rotor and stator. Or, combine the SEL-2664, SEL-2664S, and SEL-400G for an advanced generator protection solution.


SEL-2600 RTD Module

Measure and transmit data from up to 12 RTDs and a single contact status located in transformers, breakers, motors, generators, or other system apparatus.


SEL-2740S Software-Defined Network Switch

The SEL-2740S is the industry’s first field-hardened SDN switch and is designed to improve substation LANs for mission-critical applications. By providing centralized traffic engineering, the SEL-2740S combined with the SEL-5056 Software-Defined Network Flow Controller gives you path- and packet-level control of your communications flows. The SEL-2740S can also act as a transparent PTP clock supporting the IEEE C37.238 power system profile.


SEL Real-Time Automation Controller (RTAC)

SEL programmable automation controllers (PACs) are built for utility and industrial applications. They provide rugged and reliable I/O solutions at an economical price. SEL RTACs are hardened to meet stringent IEEE and IEC tests for harsh environments, and they are backed by SEL’s no-questions-asked, worldwide, ten-year product warranty.


SEL-735 Power Quality and Revenue Meter

The SEL-735 combines leading power quality capabilities with exceptional revenue metering accuracy at an economical price. Power quality reports with IEC 61000-4-30 Class A compliance help identify and troubleshoot problems in power system equipment. Advanced communications deliver critical and historical information in real time to virtually any communications system. The SEL-735 is the essential meter for substation, power plant, and industrial metering.


SEL-2523 Annunciator Panel

The SEL-2523 has 42 inputs and 11 outputs, making it a great fit for traditional annunciation. Its programmable logic and up to four communications ports supporting DNP3, Modbus, and SEL protocols allow it to make easy work of your most demanding applications.


SEL-2414 Transformer Monitor

The SEL-2414 provides standalone or distributed monitoring and control of transformers. With flexible communications options, it can connect to a SCADA or automation system. Multiple I/O options are available to help you monitor your system.


SEL-2505 Remote I/O Module

The SEL-2505 provides simple bus protection using contact inputs and outputs from existing relays. It can also provide secure pilot communications for existing two- and three-terminal line applications. In addition, you can add local or remote trip- and close-coil monitoring capability.


Generator Protection

Numerous current, voltage, frequency, distance, power, and out-of-step elements in SEL generator protection relays provide comprehensive protection for large, medium, and small generators.

Unit Protection

Apply sensitive percentage-restrained current differential elements and an unrestrained element, along with synchronism-check and volts-per-hertz elements, to protect both the generator and the step-up transformer. Harmonic-blocking elements protect the unit transformer bushing and end windings while maintaining security for inrush and through-fault conditions.

Stator/Field Ground Protection

With SEL generator relays, adding the neutral voltage connection provides 100 percent stator ground protection for most machines, based on third-harmonic voltage measurements. Connecting the neutral current input provides protection for solidly grounded or resistance-grounded machines. State-of-the-art voltage injection allows you to monitor field ground resistance.

Dual Differential Zone Protection

The SEL-400G Advanced Generator Protection System has two independent, universal differential elements, which provide protection for two independent protection zones. This allows separate generator and step-up transformer protection in a single device.

Resistance Temperature Detector (RTD)-Based Thermal Protection

Acquire thermal data for alarm, monitoring, and trip functions in SEL relays with an external SEL-2600 RTD Module, which provides 12 RTDs.


Use the optional, built-in automatic synchronizer function in either the SEL-700G Generator Protection Relay or SEL-400G to automatically synchronize the frequency, voltage, and phase angle of the generator and connect to the power system. This eliminates the need for expensive external synchronizing equipment.

Metering and Reporting

View generator automatic synchronizer, SER, and 180-cycle oscillographic event reports in COMTRADE and CEV formats to analyze generator startup, shutdown, or system faults. SEL relays measure electrical, thermal, and generator run-time quantities.

Software-Defined Networking

Traditional Ethernet switches generally behave similarly regardless of the environment (one size fits all). With SDN, LAN switching can be tuned or optimized for the specific requirements of the environment. Only SEL has implemented SDN with the goal of optimizing an operational technology (OT) network. SEL SDN allows you to purpose-engineer networks like you purpose-engineer the power system.

Advanced Time Synchronization

The SEL-2488 Satellite-Synchronized Network Clock receives Global Navigation Satellite System (GNSS) time signals and distributes precise time via multiple output protocols, including IRIG-B; the Precision Time Protocol (PTP) to serve as a grandmaster clock, as defined by IEEE 1588; and the Network Time Protocol (NTP).