html{display:none} SEL-3355 Rack-Mount Computer | Schweitzer Engineering Laboratories


Rack-Mount Computer

The SEL-3355 hardened industrial substation computer is built to withstand harsh environments in utility and industrial applications. By eliminating all moving parts, including rotating hard drives and fans, and using error-correcting code (ECC) memory technology, SEL computers have over ten times the mean time between failures (MTBF) of typical industrial computers. Designed, manufactured, and tested to the same standards as our protective relays, every SEL-3355 comes with an industry-leading ten-year warranty and is made in the USA. Discover why made in the USA is important.

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Industrial Automation Platform—Deploy complete automation control and operator station functionality in a single package directly to the plant floor without the concern of environmental conditions. SEL rugged computers are powerful and reliable computing platforms that support soft programmable logic controllers (PLCs) and operator HMI control engines. Design engineers can leverage virtual machine (VM) resources integrated into the chipset of SEL computers to reduce project costs. SEL computers are available with Xeon quad-core 2.0 GHz and 2.8 GHz processors to meet the needs of even the most demanding computing applications.

HMI Visualization, Monitoring, and Control—Make a secure system visualization, monitoring, and control point for your substation or plant. You can leverage CIS Security Benchmarks settings to meet NERC CIP and other industry compliance standards.

Information Processor: Data Concentrator/Protocol Converter—Collect and format relay data for legacy remote terminal units (RTUs), and send the data directly to SCADA systems using legacy protocols. You can leverage multiple paths for data access, collect data at one rate, and service them to any client via any supported protocol.

Centralized Authentication Server—Extend central authentication to your branch office or substation by logging in with enterprise credentials and using the same account throughout your network. You can set up role-based access controls and employ high-availability services for always-on service.

Original Equipment Manufacturer (OEM) Software Appliance—The SEL-3355 has the processing power and rugged hardware necessary for operating in critical infrastructure environments. Whether you are currently shipping a tough appliance or thinking about deploying your software as a dedicated appliance for rugged environments, consider the SEL-3355 to complement your solution.

Synchrophasor Archiver, Server, and Console—Install a single rugged computing platform to concentrate, archive, and display synchronized phasor measurements from a wide area with SEL-5073 synchroWAVe Phasor Data Concentrator (PDC) Software. Implementing RAID capabilities provides the fastest and most reliable database storage.

Engineering Workstation—Meet or exceed IEEE 1613 and protective relay specifications for harsh environments with any SEL computer, made to withstand vibration, electrical surges, fast transients, and extreme temperatures. You can access the engineering workstation remotely and securely using Microsoft Windows Remote Desktop tunneled over IPsec or through Intel Active Management Technology (AMT) with remote KVM over IP.


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      Test all LEDs with the lamp test button

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      The “ENABLED” LED shows the operational status. Green indicates normal operation, and red indicates that the system is halted or booting or that an error condition has occurred.

      The "ALARM" LED indicates that a nonoptimal system condition exists. The alarm LED illuminates red when the alarm contact operates.

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      Link and activity LEDs show the link status and network activity on each Ethernet port

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      Transmit and receive LEDs indicate activity on serial ports

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      See hard disk drive activity at a glance with the LED indicator

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      Three programmable bicolor LEDs are available for custom applications

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      Install up to four hot-swappable SSDs behind the easily accessible front panel. You can tailor the drive technology to your application with SLC, MLC, and iMLC SSD options. A RAID configuration provides even higher data availability.

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      Attach one or two USB 3.1 devices, enabling custom, application-specific peripherals

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      Connect up to three independent digital displays using one DisplayPort and two DVI-D interfaces

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      The two high-speed Gigabit Ethernet ports can be teamed for redundancy or used individually

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      Attach up to four USB 3.1 devices, enabling custom, application-specific peripherals

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      Use the line-in, line-out, and microphone jacks for high-definition analog audio applications

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      Two built-in EIA-232 ports are configurable for +5 V on Pin 1

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      DisplayPort technology provides higher performance features than other digital interfaces

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      Wire a Form C alarm contact output either normally closed or normally open. The alarm LED on the front provides indication of the alarm contact state.

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      Use SEL rugged or third-party PCI expansion cards for additional networking, serial, time, video, or other applications

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      Choose dual power supplies, and attach power from independent sources for increased availability. The supplies are hot-swappable for maximum online serviceability.



Industrial computer systems require 24/7 availability and ease of service when necessary. In order to address these needs, SEL computers employ “server class” reliability, availability, and serviceability (RAS) attributes.

SEL designs, manufactures, and tests every computer in-house. Our computing systems currently have an MTBF of over 100 years, ten times higher than that of the typical industrial computer. And, SEL computers are backed by a ten-year, no-questions-asked warranty.

Designed to keep your system operational for longer periods, the SEL-3355 can be optioned with dual load-sharing power supplies and a RAID-configurable four-bay SSD enclosure. The SEL-3355 includes either an Intel Core i7 multicore or a Xeon quad-core processor. SEL computers also feature SEL’s unique system monitor (SysMon) with a watchdog timer.

Intel AMT allows you to view logs for evaluation and service even when the unit is powered off. You can reboot into another OS for diagnostics or to batch software and then bring the system back online, all remotely. Additionally, SEL’s SysMon logs computer events specific to the installed system to aid in quick recovery.

Robust Hardware Design
SEL computers are designed for maximum reliability, with no fans or moving parts, and are backed by a ten-year warranty. The SEL-3355 has a durable power supply, an advanced thermal management system, error-correcting memory, and single-level cell (SLC) SSDs to provide reliable operation in the harshest environments.

Reliable Operation—Meets IEEE 1613, IEEE C37.90, and IEC 60255 Protective Relay Standards
Install the SEL-3355 in harsh environments. It is designed to withstand 15 kV electrostatic discharge, fast transients, radiated emissions, up to 15 g shock, seismic and sustained vibration, overcurrent, dielectric strength, and pulse magnetic field disturbances.

Wide-Range Power Supply
The power supply supports 120/240 Vac or 125/250 Vdc. You can choose two power supplies and use one with 120 Vac and the other with 125 Vdc for backup.

Watchdog Functionality
Monitor and alarm for numerous system services and conditions with an embedded controller that provides an extra level of computer system reliability. The embedded controller includes a programmable system monitor interface and alarm configuration.

High-Performance Intel Core i7 Multicore and Xeon Quad-Core Processors
The SEL-3355 features Intel multicore processors with Intel vPro technology and up to 32 GB of ECC RAM, providing the power you need for any application.

Multiple I/O Ports
Directly connect to various local peripherals and high-speed network interfaces with two Ethernet ports, audio I/O, six USB 3.1 ports, three digital video ports, and two serial ports.

Flexibility With PCI Slots
Four PCI Express and one legacy PCI expansion slots let you add additional serial ports, Ethernet ports, I/O, or other PCI Express cards that your application requires.

Operating System Choices
You can purchase the SEL-3355 as hardware-only or with a variety of modern Microsoft Windows OSs to provide extreme flexibility and functionality along with enhanced security features.

Large Storage Capacity
With a four-drive SSD bay, you can create one large volume or configure a typical RAID system that provides redundant and more reliable storage. The following SSD options are available:

  • SLC—highest endurance and reliability
  • Commercial multilevel cell (MLC)—highest capacity, lower cost
  • Industrial MLC (iMLC)—higher capacity with reduced endurance

Operating Systems

  • Microsoft Windows 10 loT Enterprise LTSC
  • Microsoft Windows Server 2016 Standard (CALs required)
  • Microsoft Windows Server 2019 (CALs required)
  • Linux (drivers available for REHL 6/7, CentOS 6/7, and Ubuntu 16.04/18.04)


Xeon quad-core 2.0 GHz is standard; Xeon quad-core 2.8 GHz is optional.


4 GB of ECC RAM is standard. Choose up to 32 GB of ECC RAM.

Storage Options

Choose from single-level cell (SLC), commercial multilevel cell (MLC), and industrial MLC (iMLC) drives from 30 GB to 1,920 GB.

Power Supply

Choose one or two hot-swappable power supplies from the available high-voltage (125–250 Vdc/120–240 Vac) and low-voltage (48 Vdc) options.

PCIe Expansion Cards

Conformal Coating

Protect equipment from harsh environments and airborne contaminants, such as hydrogen sulfide, chlorine, salt, and moisture. Learn more about conformal coating.


SEL Computers Defy Brazil’s Heat

SEL-3355 Computer Rugged, Reliable Design

SEL-3355 Computer Thermal Management

SEL-3355 Computer Design and Testing

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

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Product Certifications