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The SEL-2240 Axion is a fully integrated, modular input/output (I/O) and control solution for utility and industrial applications, including use as a remote terminal unit (RTU) or ultrarugged programmable logic controller (PLC). With an optional 7-inch color touchscreen display, the Axion is also ideal for application as a bay control unit.

The Axion combines the communications, built-in security, and IEC 61131 logic engine of the SEL Real-Time Automation Controller (RTAC) family with a durable suite of I/O modules that provide high-speed, deterministic control performance over an EtherCAT network.

All of the Axion modules are rated from –40° to +85°C (–40° to +185°F) and can optionally include conformal coating. The system is designed to be flexible; use the right combination of modules and nodes in almost any arrangement to suit the job. The SEL-2244-3 Digital Output Module has substation duty contacts (30 A make, 6 A carry) in order to provide reliable operation and flexible application.

The SEL-3530, SEL-3530-4, SEL-3555 RTACs, and SEL-2241 RTAC Module can all operate as the CPU for an Axion platform. They interface seamlessly with the I/O modules and provide easy integration with other serial and Ethernet devices via preinstalled communications protocols. The RTACs also support multiple SCADA/HMI channels. For high-speed communication, use EtherCAT fieldbus connections to I/O modules or optional IEC 61850 GOOSE messaging with station IEDs.

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RTAC Family Comparison Chart

Axion Modules

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NEW Bay Controller—Combine the scalable architecture of the Axion with a fully integrated, 7-inch touchscreen display and the powerful logic engine of the RTAC for a comprehensive bay control and monitoring solution. The Axion's modular configuration allows you to expand the device to control and monitor over a hundred switching devices in your substation bay. This flexible design scales to hundreds of digital and analog input and output points for a single panel. Control and monitor circuit breakers, disconnect switches, and earthing switches of multiple bays with a single Axion.

Digital Fault Recording (DFR) System—Use the SEL-3555 RTAC with Axion modules, including the SEL-2245-42 AC Protection Module, to develop DFR solutions that exceed the requirements of NERC PRC-002. The SEL-2245-42 Module features 24 kHz recording with recording group configuration for combining multiple module event reports, including digital values, into a single COMTRADE file. The SEL-3555 RTAC with SSD storage provides the perfect controller for recording applications to maintain more than the minimum ten-day storage requirement of all fault records, dynamic disturbance records, and Sequence of Events (SOE) records in the substation.

SCADA RTU—Enable substation reporting and control by using the included serial and Ethernet communications protocols along with Axion I/O modules.

Synchronized CT/PT Measurements for Advanced Control—Employ synchronized CT/PT measurements from multiple Axion chassis distributed across a substation and from multiple Axion systems for advanced time-deterministic control applications, including load shedding and microgrid control.

Flexible Synchrophasor Measurement Unit—Apply the Axion as a scalable and distributable phasor measurement unit (PMU). A single RTAC module in the primary Axion node serves IEEE C37.118.1a-2014 synchrophasor data from remote Axion PMU nodes. Remote Axion nodes use the SEL-2245-4 AC Metering Module located at the measurement points.

IEC 61850 GOOSE Concentrator—Gather a variety of substation I/O with the SEL-2244 Digital I/O Modules, and share the data with IEC 61850 GOOSE messages. Apply the protocol flexibility of the RTAC to concentrate data from non-IEC 61850 relays, and convert these data to GOOSE messages

Power Management Integration With Industrial Control System—Provide a powerful gateway between the substation and the factory using EtherNet/IP. This popular industrial protocol facilitates reliable communication between electronic devices in industrial automation systems. Use the RTAC EtherNet/IP adapter to exchange critical data for real-time monitoring, process control, and power system integration.

Automatic Trip Coil Monitoring—Assess the health of a circuit breaker by capturing trip coil performance in real time. Record trip coil dynamics, including current, voltage, and temperature during operations, and run automatic diagnostics to issue alerts for scheduling preventative maintenance.

SCADA Data Concentrator—Take advantage of multiprotocol support to collect SCADA information and process control commands, and obtain Simple Network Time Protocol (SNTP)/Network Time Protocol (NTP) time synchronization through a single communications link to each Ethernet device.

Remote I/O Expansion—Increase the number of I/O points with as many as 60 modules or six nodes connected to one resident SEL-2241 RTAC. Through EtherCAT connectivity, provide rapid data acquisition rates to the expanded I/O points within your automation system.

Event Recording—Record high-accuracy COMTRADE events with the Axion analog modules. Record up to 24 kHz event records with the SEL-2245-4 AC Metering Modules and up to 1 kHz event records from the SEL-2245-2 and SEL-2245-22 DC Analog Modules.

System Security—Enable encryption for any engineering access channel or SCADA link. Implement system security auditing, logging, and password restrictions to enforce government standards. Use web upload features and project passwords. 

Industrial Control System and PID Control—Create an ultra-rugged PLC system by combining the standard IEC 61131 logic engine, integrated database, and flexible I/O. Use ladder logic, structured text, or function chart programming for custom control strategies. Support advanced process control strategies by implementing control function blocks, such as proportional integral derivative (PID).

Substation Battery Monitoring—Monitor substation battery levels and issue alarms using the new SEL-2245-22 DC Analog Input Extended-Range Module.

EtherCAT Network Topologies—The SEL-2243 Power Couplers provide not only hot-pluggable power supplies, but also fast EtherCAT connections to remote Axion nodes. The power couplers create EtherCAT links in a star network topology, sequential network topology, or combination of both. Apply single or dual power couplers in each Axion node based on connection or redundancy requirements.

Protocol Gateway—Collect downstream data with client protocols. Then, send these data to an upstream human-machine interface (HMI), RTU, or SCADA master with server protocols, converting the data from one protocol to another in the process.


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      Capacitive 7-inch, 800 × 480 color touchscreen with full onscreen keyboard

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      Pushbutton to return to default home screen

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      Front Ethernet port for configuration and maintenance

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      Programmable tricolor LEDs for alert and status information

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      Programmable operator pushbuttons for custom control commands

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      Lamp test pushbutton

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      Diagnostic LEDs

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      Serial activity and user-programmable LEDs.

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      Two independent Ethernet ports, available in either copper or LC fiber, are capable of operating on separate subnets.

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      Four serial ports, software-selectable for EIA-232/EIA-485.

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      Panel wiring harnesses are available to simplify field termination. Choose between 8', 16', and 20' lengths.

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      Optional redundant power supply.

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      All digital inputs are rated for ac and dc operation and time-stamped to 1 ms accuracy.

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      All terminals are clearly numbered for wiring and testing.

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      Choose fast, high-current digital outputs for applications requiring fast action (<50 µs) or interrupting high current (up to 10 A).

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      Indicating LED for each input and output.

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      DC analog inputs are software-selectable for ±20 mA, ±2 mA, or ±10 V input ranges.

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      Measure ac signals with three current and three voltage inputs for recording or protection functions.

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      Self-sourcing dc analog outputs are software-selectable for ±20 mA or ±10 V.

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      Collect synchronized ac measurements (5–400 V, 0–22 A) with an accuracy of 0.1 percent on the SEL-2245-4 AC Metering Module.

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      Use copper or fiber EtherCAT ports to add more Axion nodes.
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      Select from predefined bay screens or configure as many as 25 custom bay screens using the Bay Screen Builder application within acSELerator RTAC. Within the 25 screens, you can control over 100 elements, including breakers, two-position disconnects, and three-position disconnects. You can also view hundreds of analog and digital data in contextual displays.

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      To control a breaker or disconnect switch, simply tap the equipment icon in the bay screen, select a command, and confirm your selection.

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      User authentication is required before issuing commands, providing robust security for device management and control. The full onscreen keyboard allows you to enter required credentials quickly and easily.

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      Access the RTAC’s SOE logs to see informative names that you can customize for your application. The SOE display includes date and time stamps with millisecond accuracy.

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      View important device information, including the SEL RTAC serial number, firmware version, project history, and more.

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      View the Axion module status for each slot and node in the system. The Module Status screen conveniently indicates the operational or alarm status for all slots, including those in remote nodes.



Complete Bay Control and Monitoring
Control and monitor breakers, switches, and other vital substation assets using the Axion’s new 7-inch color touchscreen. Create up to 25 custom bay screens using the new Bay Screen Builder application in acSELerator RTAC SEL-5033 Software.

RTU and Programmable Automation Controller (PAC) in a Single System
The Axion includes I/O, SCADA communications, and control logic support for many industrial and utility applications.

Synchronized Current and Voltage Measurements
The Axion CT/PT Module provides time-aligned current and voltage measurements for high-accuracy waveform recording and advanced power control algorithms.

Top-of-the-Second Synchronized Measurements
All measurements of the SEL-2245-4 AC Metering Module are synchronized to the top of the second to provide time-aligned data for wide-area control schemes with multiple Axion systems.

Modular Phasor Measurement Unit
Stream and process IEEE C37.118.1 compliant synchrophasor messages via the SEL-2245-4 AC Metering Module, which has 4 CT and 4 PT inputs, as well as the SEL-2244-2 Digital Input Module, which has 24 digital inputs.

Simple Setup With acSELerator RTAC Software
Build a system quickly, including I/O modules, using standard device templates.

Flexible I/O Selections
Choose a custom mix of digital I/O modules that suit the application. Include hundreds of points in a single panel, all connected to a deterministic EtherCAT network.

Advanced User Authentication and System Security
Enforce Lightweight Directory Access Protocol (LDAP) user accounts to maintain security perimeter integrity. Apply security corporate logging and port control policies to comply with NERC CIP requirements.

Deterministic I/O Performance
The connected I/O is updated at a deterministic frequency; all inputs provide 1 ms Sequential Events Recorder (SER) time stamps.

More Than SCADA
The Axion includes industry-standard communications protocols to enable multiple SCADA connections as well as distributed control networks among many stations.

Networking Options
Implement I/O networks that use optional fiber-optic cables to provide outstanding signal isolation and flexibility in module placement.

Concentrate and manage data from new and legacy relays and other IEDs using our extensive set of protocols.

Minimum QuickSet Version


Pend Oreille Upgrades Substation with innovative SEL RTAC, Axion and cabling solution

Video Playlists

Videos in this series:

  • How To Install SEL-2240 Axion®
  • How To Set SEL-2240 Axion® Configuring an EtherCat Network
  • How To Set SEL-2240 Axion® Configuring PMU Functionality

Videos in this series:

  • How to Use the RTAC HMI, Part 1: acSELerator Diagram Builder™ Overview
  • How to Use the RTAC HMI, Part 2: Building a Project
  • How to Use the RTAC HMI, Part 3: Shared Tags

Latest Firmware Versions

There are no firmware versions available for this product.

Product Revision Firmware ID Date Available Serial Number
SEL-2241 R149-V0 SEL-2241-R149-V0-Z000004-D20210915 9/22/21 ~3212650001
SEL-2245-2 R102-V0 SEL-2245-2-R102-V0-Z001001-D20140612 8/6/14 ~1142180001
SEL-2245-22 R101-V0 SEL-2245-22-R101-V0-Z001001-D20171107 11/29/17 ~3173330001
SEL-2245-221 R102-V0 SEL-2245-22-R102-V0-Z001001-D20181207 2/8/19 ~3190390001
SEL-2245-3 R101-V0 SEL-2245-3-R101-V0-Z001001-D20150123 2/17/15 ~1150480001
SEL-2245-41 R103-V1 SEL-2245-4-R103-V1-Z001001-D20180629 7/7/18 ~3181880001
SEL-2245-411 R105-V0 SEL-2245-4-R105-V0-Z001001-D20181207 2/8/19 ~3190390001
SEL-2245-42 R104-V0 SEL-2245-42-R104-V0-Z001001-D20200731 8/28/20 ~3202410001

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

Minimum QuickSet Version

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Download the acSELerator RTAC library extensions, and take advantage of the flexibility that the SEL RTAC product line provides for your automation and integration applications. These library extensions are prebuilt code components for the advanced users of the SEL RTAC. Once downloaded, the instruction manuals for each of the library extensions will be accessible via the acSELerator RTAC help menu.

You can find the instruction manuals for the general purpose and optional libraries in the Programming Reference.

General Purpose Toolbox Libraries (Complimentary)

AnalogCondProcess analog quantities and digital filtering.
CrossTaskDataShare data between Main and Automation tasks.
ChannelMonitoringProvide alerts when a channel deviates from user-defined parameters.
DictionariesCreate lookup tables for fast data retrieval.
DynamicVectorsStore an arbitrary number of items, such as an automatically resizing array.
EmailSend alerts and notifications from an RTAC to a mail server.
IPAliasRedundancyShare a single IP between two RTACs in a redundancy scheme by using an IP alias.
MathComplexPerform mathematical operations on values with real and imaginary components.
MathMatrixPerform common matrix operations.
PacketEncodingsSerialize and deserialize information to/from a socket connection.
PowerMeteringPerform energy and demand calculations.
PowerSystemProtectionIdentify fault conditions, and unlock the potential of the SEL-2245-42 AC Protection Module.
QueueKeep track of ordered lists of objects.
QuickSortSort objects.
RecordingTriggersDetect specific conditions in analog and digital signals to initiate the capture of data.
SELEthernetControllerManage both UDP and TCP raw socket connections.
SELRandGenerate random numbers.
SELServerSimulatorsSimulate an SEL-351 client.
SELStringCombine and split strings in constant time.
SnmpLiteIdentify and troubleshoot network connectivity.
SyslogCollectorReceive Syslog messages from other devices.

Optional Value-Added Automation Solutions

To select any of the following libraries, choose the library as an option in the RTAC hardware configuration.

LibraryApplication/DetailsDependency Libraries
Grid Connection ControlControl the point of common coupling (PCC) between the utility and renewable power generation sources.Dynamic Disturbance Recorder, File I/O
Horizon SVP PlusTurn the RTAC into a synchrophasor vector processor. Detect the onset of uncontrolled wide-area oscillations with SVPplus modal analysis.None
Horizon Power System ModelResolve synchrophasor data streams using a model of the power system.File I/O
Dynamic Disturbance RecorderCollect data from within the logic engine to generate Sequence of Events (SOE), time-aligned CSV, and COMTRADE files in the RTAC.File I/O
Meter Trend RecorderRecord analog data in the RTAC, and send data to acSELerator Team SEL-5045 and acSELerator Meter Reports SEL-5630 Software for analysis.File I/O
Report Generator/EmailPlus ClientGenerate custom reports from data available from the RTAC's logic engine. It is bundled with a fully featured email client that integrates into secure email systems. File I/O
FTP SyncConnect to established S/FTP server infrastructure and automatically push files from the RTAC file system to remote destinations. File I/O
File I/ORead and write files to the RTAC file system. It includes a built-in SFTP/FTP client for sending and receiving files and provides programmatic access to fault and SOE records.None

Engineering Services Libraries (Contact Engineering Services for ordering information.)

Distribution AutomationFault location, isolation, restoration, and volt-VAR control of distribution feeders
Automated System Verification and MonitoringProtection system monitoring and verification (NERC PRC-005)
Ground Fault DetectionGround fault identification for ungrounded power systems