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SEL-7251

Electromechanical Direct-Replacement Assemblies

Streamline retrofit projects by replacing electromechanical relays with SEL direct-replacement assemblies. These complete, preassembled retrofit kits combine a field-proven SEL digital relay with mounting plates, interposing terminal blocks, test switches, and other hardware that closely match the function, form factor, and terminal blocks of specific legacy relays.


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Simplify Installation and Configuration—Install direct-replacement assemblies in only a few hours, with minimal panel changes. Assemblies are designed to replace sets of three electromechanical relays that are aligned horizontally on the same panel; only simple cuts are required to remove the dividers between the old relays. Terminal block arrangements and wiring designations closely match legacy products, and SEL provides wiring marking labels with all retrofit kits.

Modernize With Advanced Technology—SEL solutions offer the fastest, most reliable protection available. They also improve systemwide visibility and control through cybersecure remote engineering access, automated event collection, and precise fault location, among other benefits.

Minimize Engineering Work—Eliminate time-intensive and costly engineering tasks, such as revising drawings and diagrams. All assembly kits include conversion drawings, so modification of the existing documentation for your system is not required for installation.

Target Specific Assets for Upgrades—Because SEL direct-replacement assemblies don’t necessitate a full replacement of switchgear or panels, you can replace legacy relays piece by piece and modernize in economical stages.

Partner With SEL on a Turnkey Solution—SEL offers services that include system design, settings conversion, installation, and commissioning—everything needed for a complete turnkey retrofit solution. We also create custom assembly designs to meet specific protection, communications, and mounting requirements.

Get the Industry’s Best Support—All SEL-manufactured products and workmanship within panels and enclosures are backed by a worldwide, ten-year warranty. Diagnostic services, repairs, and local technical support are available for the lifetime of every SEL-manufactured device—at no extra cost. Third-party devices carry a transferred manufacturer warranty.

Related Materials

Purpose-Built Replacements

Direct-replacement assemblies are available to replace the electromechanical relay models listed below.

Features

    1. 1

      SEL-787

    2. 2

      Relay power, CT, and control terminal blocks

    3. 3

      Relay mounting plate

    4. 4

      SEL-787

    5. 5

      Two 14-pole test switches with clear covers

    6. 6

      Configurable label nameplate for test switches

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    2
    3
    4
    5
    6
    1. 1

      Neutral relay plate (if applicable)

    2. 2

      Neutral relay CT and control terminal blocks (if applicable)

    3. 3

      Relay power and PT terminal block

    4. 4

      SEL-751

    5. 5

      CT and control terminal blocks

    6. 6

      SEL-751

    7. 7

      Configurable nameplate

    8. 8

      Relay mounting plate

    9. 9

      14-pole test switch with clear cover

    10. 10

      Neutral terminal block plate (if applicable)

    1
    2
    3
    4
    5
    6
    7
    8
    9
    10
    1. 1

      Neutral relay plate (if applicable)

    2. 2

      Relay power and PT terminal block

    3. 3

      SEL-851

    4. 4

      Neutral relay CT and control terminal blocks (if applicable)

    5. 5

      CT and control terminal blocks

    6. 6

      SEL-851

    7. 7

      Relay mounting plate

    8. 8

      Configurable nameplate

    9. 9

      14-pole test switch with clear cover

    10. 10

      Neutral terminal block plate (if applicable)

    1
    2
    3
    4
    5
    6
    7
    8
    9
    10
    1. 1

      SEL-787Z

    2. 2

      SEL-HZM

    3. 3

      Relay power, CT, and control terminal blocks

    4. 4

      SEL-HZM

    5. 5

      Relay mounting plate

    6. 6

      Configurable label nameplate for test switches

    7. 7

      Two 14-pole test switches with clear covers

    8. 8

      SEL-787Z

    1
    2
    3
    4
    5
    6
    7
    8
    1. 1

      Neutral relay plate (if applicable)

    2. 2

      Relay power and PT terminal block

    3. 3

      SEL-751

    4. 4

      Neutral relay CT and control terminal blocks (if applicable)

    5. 5

      CT and control terminal blocks

    6. 6

      SEL-751

    7. 7

      Relay mounting plate

    8. 8

      Configurable label test switch nameplate

    9. 9

      14-pole test switch with clear cover

    10. 10

      Neutral terminal block plate (if applicable)

    1
    2
    3
    4
    5
    6
    7
    8
    9
    10
    1. 1

      Neutral relay plate (if applicable)

    2. 2

      Relay power and PT terminal block

    3. 3

      SEL-851

    4. 4

      Neutral relay CT and control terminal blocks (if applicable)

    5. 5

      CT and control terminal blocks

    6. 6

      SEL-851

    7. 7

      Relay mounting plate

    8. 8

      Configurable nameplate

    9. 9

      Neutral terminal block plate (if applicable)

    1
    2
    3
    4
    5
    6
    7
    8
    9

Electromechanical Direct-Replacement Assembly Models

Electromechanical Direct-Replacement Assembly Models

Details

SEL direct-replacement assemblies embody best practices in engineering and field-tested expertise in mechanical design, cable management, protection, precise time, automation, and communications.

The SEL Difference

Direct-replacement assemblies are manufactured according to the same world-class manufacturing principles we use for all our industry-leading products. This allows us to design, manufacture, test, and deliver high-quality and comprehensive solutions.

Vertical integration and standardized application designs help us maintain competitive prices and quality while still meeting the highest functionality requirements and offering delivery within weeks—not months.

Design Validation That Guarantees Expected Performance

We build a prototype of and test each application module design to ensure it meets functional specifications. This procedure allows our manufacturing facility to properly document processes and test manufacturing equipment for production.

Quality

We engineer, manufacture, and test our direct-replacement assemblies to ensure adequate operation before delivery.

Application Considerations

Because digital devices have different space and operational requirements than electromechanical relays and relay and panel wiring methods vary, you’ll want to consider these factors when planning a direct-replacement assembly installation.

If these parameters don’t work for your application, please contact SEL Engineering Services. We’ll be happy to discuss a custom assembly design to meet your needs.

Panel and Relay Configuration

Existing sets of three electromechanical relays need to be collocated on the same panel and aligned horizontally.

  • The gap between each relay should be no larger than 1" (26 mm) for easiest application.
  • Gaps may be up to 1.125" (30 mm) if additional bolts or screws are installed to plug holes remaining from the legacy device mounting.

For 50/51 overcurrent protection applications with an existing neutral relay, the neutral relay needs to be collocated on the same panel either to the immediate left or right of or directly above or below one of the existing three-phase relays.

Power Supply

A power source for the SEL relay needs to be routed to the direct-replacement assembly. SEL relays accept 110–250 Vdc/110–240 Vac and 24–48 Vdc power supplies.

Wiring and Connections

All outputs should be parallel-connected for each phase or neutral unit on a common trip bus.

Test switches are C-C style FT configuration with a test plug and jack for each phase and neutral CT.

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