SE-105 Series

Ground-Fault Ground-Check Monitor

The SE-105/SE-107 is a combination ground-wire monitor and ground-fault relay for resistance-grounded systems. It continuously monitors the integrity of the ground conductor to protect portable equipment from hazardous voltages caused by ground faults. The SE-105/SE-107 is an excellent choice for trailing cables 5 kV and under in underground mining applications. For higher voltages or long-cable applications, see the SE-134C/SE-135.


Littelfuse website

Features & Benefits

  • Adjustable pickup (0.5, 2.0, 4.0 A)

    Unit can be used on a wide variety of trailing cable applications

  • Adjustable time delay (0.1 - 2.0 s)

    Adjustable trip delay for quick protection and system coordination

  • Harmonic filter

    Prevents false operation

  • Zener-characteristic termination assembly

    Provides reliable ground-check loop verification

  • Fail-safe ground-check circuit

    Ensures ground-check circuit remains safe even in the event of equipment failure

  • Conformal coating

    Additional coating protects circuit boards against harsh environment

  • SE-105: selectable UV or shunt-trip mode

    Provides flexibility for different applications

  • SE-107: UV-trip mode only

    Eliminates chance of unauthorized change to trip circuit

Ordering Information

120 Vac
120 Vac/Vdc
240 Vac
120 Vac
120 Vac/Vdc
240 Vac


CT200 Series
SE-TA6A Series
RK-102, RK-105, RK-105I


  • IEEE Device Numbers:  Checking or Interlocking Relay (3GC), Ground Fault (50G/N, 51G/N)
  • Input Voltage:  See ordering information
  • Dimensions:  H 150 mm (5.9”), W 109 mm (4.3”), D 100 mm (4.0”)
  • Trip Level Settings:  0.5, 2.0, 4.0 A
  • Trip Time Settings:  0.1-1.0 s
  • Contact Operating Mode:  Selectable fail-safe or non-fail-safe (SE-105), Fail-safe only (SE-107)
  • Harmonic Filtering:  Standard feature
  • Reset Button:  Local and remote
  • Output Contacts:  Isolated Form A
  • Approvals:  CSA certified, UL Listed (E340889), C-Tick (Australian)
  • Conformally Coated:  Standard feature
  • Warranty:  5 years
  • Mounting:  Surface

Technical Resources

SE-105 SE-107 Datasheet

SE-105 Manual

SE-105 Manual French

SE-105 CAD Drawing

RK-105 CAD Drawing

SE-MON GFGC Software

Littelfuse Protection Relays Ground-Fault Paper TN

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It’s been a pleasure working with Fuseco on this project. Initially, we thought that the power quality issues on this job were insurmountable. Fuseco conducted a power quality site audit and consulted with us to find a suitable solution that would work reliably in this challenging environment. The reactors and harmonic filters specified & supplied by Fuseco have been the perfect solution.

Peter Carney


Just wanted to say thank you again to the Fuseco team. When presented with an electrical harmonics problem of this nature, I wasn’t sure how to approach it. You guys explained it in logical, scientific terms and expertly demonstrated the capability of your technology. It is now one month post-installation and I can say that the Active Filter is working well and the harmonics levels on this site are now negligible.

John Ulverstone


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