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Transformer Protection Relay

Protect and monitor transformers with the SEL-487E. It offers up to six three-phase restraint inputs, three independent restricted earth fault (REF) protection elements, and two three-phase voltage inputs. The SEL-487E limits transformer damage by responding to internal fault conditions in less than 1.5 cycles. The relay also helps avoid catastrophic transformer failure by detecting turn-to-turn faults involving as little as 2 percent of the total winding. You can minimize commissioning time and eliminate costly errors with included software that recommends matrix compensation settings. Through-fault and thermal monitoring allow you to track transformer wear and schedule maintenance as necessary. Breaker wear monitoring reduces inefficient and costly breaker maintenance, saving time and money. The SEL-487E includes two differential elements as well as comprehensive feeder and distance protection, making it well suited for protecting a distribution substation using a single device. Apply the SEL-487E-4, with its 6 voltage and 18 current terminals, as a station phasor measurement unit.

Transform the way you modernize your substation with optional Time-Domain Link (TiDL) technology or Sampled Values (SV)-based technology using IEC 61850-9-2.

SEL-400 Series Relay Mimic Diagrams

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Multiwinding Protection—Configure the SEL-487E for transformer differential protection in transformer applications using up to six restraint currents. This includes single transformers with tertiary windings. Three independent REF elements provide protection of grounded-wye windings. You can invert individual or grouped CT or PT polarities to account for field wiring or protection zone changes.

Sensitive Turn-to-Turn Fault Detection—Avoid catastrophic transformer failure by detecting turn-to-turn faults involving as little as two percent of the total winding with the patented negative-sequence differential element.

High-Speed, Adaptive Differential Protection—Implement a two-stage slope that automatically adapts to internal or external fault conditions, even with CT saturation and heavily distorted waveforms, for fast, sensitive, dependable, and secure differential protection. The adaptive differential element responds to internal fault conditions in less than 1.5 cycles.

Diverse Applications—Protect large transformers with breaker-and-a-half high- and low-side connections. With a typical two-winding transformer application, you can use the remaining three-phase current inputs for feeder backup protection.

Generator Step-Up Transformer Protection—Protect generator step-up (GSU) transformers, and apply the built-in thermal elements for monitoring and protecting generator and transformer winding temperatures simultaneously. Thermal elements require inputs from the SEL-2600 RTD Module.

Advanced Asset Monitoring—Track transformer wear with through-fault and thermal monitoring. Advanced breaker monitoring helps reduce inefficient and costly breaker maintenance. The SEL-487E can monitor substation dc power systems for out-of-tolerance voltage levels or excessive voltage ripple.

Configurable Distance Protection—Apply up to four zones of phase and ground distance protection, using mho or quadrilateral characteristics. The SEL-487E distance elements can be applied as transmission line or transformer protection.

Dependable Backup Protection—Provide backup protection with phase-, negative-, and zero-sequence overcurrent elements and 20 configurable time-overcurrent elements. The SEL-487E helps you quickly identify the faulted phase with faulted-phase indications for each overcurrent element. You can set up breaker failure protection with subsidence detection to rapidly detect breaker open conditions and minimize system coordination times.

Centralized Protection and Control (CPC) Solution—Simultaneously protect multiple assets using differential elements for dedicated transformer and bus protection as well as comprehensive distance protection and feeder protection in one relay. Familiar logic and settings in the SEL-487E ensure an easier transition when you deploy CPC solutions in your system.

Station Phasor Measurement Unit (PMU)—Improve power system quality using synchrophasors (IEEE C37.118) from all 24 analog channels (6 voltage and 18 current sources) in your relay. Use synchrophasors over serial or Ethernet communications to easily detect reactive loop flows, turn state estimation into state measurement, and provide an early warning of potential system instability. Implement real-time control and take action based on local and remote messages by configuring the SEL-487E to receive synchrophasor messages from up to two PMUs.

Digital Secondary System Technologies—SEL TiDL and SV-based solutions replace copper with fiber to increase safety, improve reliability, and limit the impact of an electromagnetic pulse. Apply the SEL-487E-5 TiDL relay with the SEL-TMU TiDL Merging Unit in the field to provide remote I/O and digitize analog signals. This simple point-to-point solution with a strong cybersecurity posture is easy to implement. Apply the IEC 61850-compliant SEL-487E-5 SV relay to receive SV data from a remote merging unit via a network. Improve system availability in SV applications with the Parallel Redundancy Protocol (PRP) or seamless failover using a five-port Ethernet card.

Flexible Communications Options—Use small form-factor pluggable (SFP) transceivers for TiDL ports as well as process bus, station bus, and engineering access ports in the five-port Ethernet card. Choose between single- and multimode communications options for increased flexibility. All ports support 100 Mbps SFP transceivers, and process bus ports also support 1 Gbps SFP transceivers.


    1. 1

      EIA-232 serial port streamlines system setup and local access.

    2. 2

      LCD allows you to control and view the status of disconnects and breakers.

    3. 3

      Easy-to-use keypad aids navigation.

    4. 4

      LEDs for viewing custom alarms provide fast and simple information to assist dispatchers and line crews with rapid power restoration.

    5. 5

      Programmable operator pushbuttons with user-configurable labels.

    1. 1

      Choose from a vertical (5U only) or horizontal, panel-mount or rack-mount chassis and different size options.

    2. 2

      Communications protocols include FTP, Telnet, synchrophasors, DNP3 LAN/WAN, PRP, IEC 61850 Edition 2 (optional feature), and the IEEE 1588 Precision Time Protocol Version 2 (PTPv2). 

    3. 3

      Use the three EIA-232 ports for Mirrored Bits communications, DNP3, SCADA, and engineering access.

    4. 4

      The 18 current and 6 voltage channels support transformer differential protection for up to 6 three-phase terminals, 3 independent REF elements, and voltage elements.

    5. 5

      Connectorized hardware configuration or a Euro connector with low-energy analog (LEA) voltage inputs provide flexibility for different line voltage sensors or optical voltage transformers.

    6. 6

      Choose from power supply options such as 24–48 Vdc; 48–125 Vdc or 110–120 Vac; or 125–250 Vdc or 110–240 Vac.

    1. 1

      4U chassis with horizontal mounting options (panel or rack) accommodates your application needs.

    2. 2

      Select a five-port Ethernet communications card for dedicated station bus and engineering access ports.

    3. 3

      LEDs indicate the connection status to an SEL-TMU on a per-port basis.

    4. 4

      Eight small form-factor pluggable (SFP) ports allow the TiDL relay to connect with eight remote SEL-TMU devices and to receive remote analog and digital data.

    1. 1

      The 4U chassis has various mounting options to accommodate hardware needs.

    2. 2

      Select a five-port Ethernet communications card for dedicated process bus, station bus, and engineering access ports.



Current Differential Protection for Up to Six Terminals
Achieve fast, sensitive, dependable, and secure differential protection. A two-stage slope adapts to internal or external fault conditions automatically, even with CT saturation and heavily distorted waveforms.

Security and Dependability
Provide maximum security during external faults and transformer magnetizing inrush conditions. You can detect internal faults quickly, during energization or normal operating conditions, using combined harmonic-blocking and -restraint differential elements. The SEL-487E detects turn-to-turn winding faults for as little as 2 percent of the total transformer winding with the negative-sequence differential element.

Additional Protection
Apply two three-phase voltage inputs for over- and undervoltage, frequency, synchronism check, and volts-per-hertz protection. You can make any overcurrent element directional using voltage-polarized directional elements as torque control inputs to the overcurrent elements. Adaptive time-overcurrent (IDMT) elements allow you to implement transformer and feeder protection. Three independent REF elements enable sensitive ground fault detection in grounded wye transformer applications. Assign the distance element to any terminal on the SEL-487E to provide up to four reversible zones of distance protection. The distance elements can be used for traditional line protection or as part of a transformer protection scheme. Apply the second differential element for bus bar protection. The SEL-487E includes comprehensive feeder protection, including reclosing, and a single device can protect up to six feeders.

Centralized Protection and Control
The SEL-487E delivers a CPC solution that offers complete protection for small substations and is highly adaptable, maximizing the benefits of any given application. Connect to conventional instrument transformers using traditional copper connections or as part of a digital secondary system (DSS) solution, such as IEC 61850-9-2 SV or  SEL TiDL technology. In these DSS applications, merging units acquire data close to the instrument transformers and send the data to remote SEL-487E relays to provide the required information.

Send IEEE C37.118 synchrophasor messages over serial or Ethernet communications to detect reactive loop flows, turn state estimation into state measurement, and provide early warning of potential system instability. Apply control functions based on phase angles, currents, and voltages for basic or advanced applications. Multicast synchrophasor data to simplify system architecture and improve system operations. For applications requiring a dedicated PMU, choose the SEL-487E-4 Station Phasor Measurement Unit.

Monitoring and Asset Management
Monitor and protect critical substation assets with the IEEE C57.91 and IEC 60255-149 thermal models for mineral oil-immersed transformers. You can use the IEC thermal element to trip a breaker or use either the IEC or the IEEE thermal elements to activate a control action or issue an alarm when the transformer is in danger of excessive insulation aging or loss of life. Advanced monitoring features include transformer through fault, substation battery voltage, and comprehensive breaker wear monitoring.

Metering and Reporting
Eliminate external recorder and metering requirements with oscillographic event reports, Sequential Events Recorder (SER) reporting, and three-phase power metering. These tools simplify post-fault analysis and improve your understanding of protective scheme operations.

Front-Panel One-Line Diagrams Control and Monitoring
Select your own system bay configuration, and control as many as 6 breakers and 20 disconnect switches using the built-in mimic diagrams that include programmable analog quantities for readouts.

Automation and Control
Implement SELogic control equations with SELogic variables, timers, latch bits, and remote control elements for customizing advanced protection and control schemes. Control logic can replace panel control switches, RTU-to-relay wiring, latching relays, and traditional indicating panel lights.

SEL TiDL-Based Solutions
Apply a TiDL-based process bus solution, where SEL-TMU devices are placed in the yard close to the primary equipment to digitize discrete I/O signals and analog data. SEL-TMU units exchange these data with an SEL-487E-5 TiDL relay in the control house. Each SEL-TMU can share data with as many as four TiDL relays, providing protection design flexibility.

TiDL combines the proven protection of the SEL-400 series relays with the purpose-built SEL-TMU, simplifying deployment, reducing training requirements, and increasing availability. TiDL technology uses point-to-point connections and a non-Ethernet protocol, providing a simple and secure solution. TiDL also provides built-in data synchronization and synchronous sampling, ensuring protection is available in the relay regardless of whether an external time signal is available.

SEL SV-Based Solutions
Based on the IEC 61850 standard, SV-based solutions maximize flexibility and interoperability. The SEL-401 Protection, Automation, and Control Merging Unit and the SEL-421-7 Protection, Automation, and Control System Merging Unit digitize analog signals from primary equipment and send them using the SV protocol to an SEL-487E-5 SV relay in the control house. Because all SEL SV devices are compliant with IEC 61850-9-2 and the UCA 61850-9-2LE guideline, the SEL-487E-5 SV relay can be used with other manufacturers’ IEC 61850-compliant units.

Flexible Ethernet Communications
The two-, four-, and five-port Ethernet communications card options enable you to communicate using a variety of protocols, including FTP, HTTP, DNP3, PTPv2, PRP, Telnet, synchrophasors, and IEC 61850 Edition 2.

The TiDL and SV relays can be configured with a five-port Ethernet card supporting PRP or failover functionality to increase system availability, as well as the Precision Time Protocol Version 2 (PTPv2) on process bus or station bus ports for time synchronization. Use network monitoring features in the relay to further improve system availability by actively monitoring each redundant path to detect communications network failures. 

The five-port card also features dedicated ports and IP addresses for station bus and engineering access networks to provide selective access control. All ports support SFP transceivers. Single- and multimode communications options provide increased flexibility. All ports support 100 Mbps SFP transceivers, and process bus ports also support 1 Gbps SFP transceivers.

Serial Communications
All four independent EIA-232 serial ports support SEL Fast Message, SEL ASCII, Compressed ASCII, SEL Fast Operate, SEL Fast Meter, SEL Fast SER, enhanced SEL Mirrored Bits communications, and DNP3 Level 2 Outstation as well as dial-out, Virtual Terminal, and communications with SEL-2600 series RTD modules.

Simplified Settings Management
Use acSELerator QuickSet SEL-5030 Software to develop relay settings offline and program SELogic control equations. Configure the TiDL and SV relays using SEL Grid Configurator, a software tool that increases efficiency and improves settings insights. It features a spreadsheet-style editor, protection visualization, comprehensive reporting, custom filters, and multiple-device settings management.

  • Distance protection
  • Second differential element
  • Reclosing
  • Station PMU
  • Digital secondary system solutions
    • SEL-487E-5 relay with TiDL technology
    • SEL-487E-5 relay (subscriber) with IEC 61850-9-2 SV
  • Screw terminal or Connectorized hardware configuration
  • Euro Connector with low-energy analog (LEA) voltage measurement interface
  • 24/48 Vdc, 48/125 Vdc or 120 Vac, and 125/250 Vdc or 120/240 Vac power supply options
  • AC input card configurations with a choice of 1A, 5A, or combination of 1A and 5A CT inputs
  • IEC 61850 Edition 2 communications and IEEE 1588 Precision Time Protocol Version 2 (PTPv2)
  • Ethernet connection options for primary and standby connections:
    • 10/100BASE-T
    • 100BASE-FX
  • Five-port Ethernet card supporting fiber-optic SFP transceivers and 100 Mbps or 1 Gbps data transfer rates
  • Vertical (5U chassis size only) or horizontal-, rack-, or panel-mount hardware packages
  • Up to four additional I/O boards with standard, high-interrupting, or high-speed/high-interrupting outputs
  • Conformal Coating: Protect equipment from harsh environments and airborne contaminants, such as hydrogen sulfide, chlorine, salt, and moisture.

Minimum Software Version

Latest Firmware Versions

There are no firmware versions available for this product.

Product Revision Firmware ID Date Available Serial Number
SEL-487E R114 SEL-487E-R114-V0-Z006002-D20121126 12/4/12 ~1123390001
SEL-487E-2 R114 SEL-487E-2-R114-V0-Z006002-D20121126 12/4/12 ~1123390001
SEL-487E-3 R322-V1 SEL-487E-3-R322-V1-Z115104-D20240509 5/22/24 ~1241430001
SEL-487E-4 R322-V1 SEL-487E-4-R322-V1-Z115104-D20240509 5/22/24 ~1241430001
SEL-487E-5 R406-V0 SEL-487E-5-R406-V0-Z205202-D20240509 5/22/24 ~1241430001

The Firmware IDs for older versions of the firmware can typically be found in Appendix A of the instruction manual.

Minimum Software Version

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411L 421 451 487B 487E - Software Tab

Configuration Software

acSELerator QuickSet SEL-5030 Software

QuickSet is a tool for engineers and technicians to quickly and easily configure, commission, and manage power system devices. QuickSet includes a Graphical Logic Editor and a device template tool to reduce configuration time and streamline deployment.

Learn more and download on the QuickSet software page.

SEL-5037 Grid Configurator Software

SEL Grid Configurator is a no-charge software tool for engineers and technicians to create, manage, and deploy settings for SEL power system devices.

Learn more and download on the Grid Configurator software page.

acSELerator Architect SEL-5032 Software

Architect allows users to configure and document IEC 61850 systems that include GOOSE, Sampled Values (SV), or Manufacturing Message Specification (MMS) communications. Architect automatically compares SCL files with IEC 61850 requirements to ensure standard compliance.

Learn more and download on the Architect software page.

Automated Data Collection

SEL Data Management and Automation (DMA) Application Suite

Available on the Blueframe platform, DMA applications automatically collect, store, and manage device-specific information like oscillography, Sequence of Events (SOE) data, device settings, and property information. They also provide automated password rotation and streamlined device audits.

Learn more on the DMA software page.

Visualization and Analysis

SEL-5601-2 synchroWAVe Event Software

synchroWAVe Event helps engineers diagnose a protective relay’s behavior during a power system fault. It is a powerful and easy-to-use solution for displaying and analyzing SEL relay event reports and COMTRADE files.

Learn more and download on the synchroWAVe Event software page.

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