Combined overcurrent and earth-fault relay SPAJ 144 C

Not active product since 2011

The combined phase and neutral overcurrent relay SPAJ 144 C is used for the selective short-circuit and time overcurrent protection of radial feeders in distribution networks. The relay is also used for feeder earth-fault protection in isolated neutral networks and networks with resistively earthed neutral. The overcurrent unit includes three protection stages and the earth-fault unit two. Further, the relay includes a phase discontinuity protection unit and an integrated circuit-breaker failure protection unit.

The phase and neutral overcurrent relay is provided with serial communication capabilities. Vital relay information is immediately available to the relay operator, locally or remotely. Therefore, the phase and neutral overcurrent relays can be used for any application, ranging from stand-alone relay applications to advanced applications comprising fully remote-controlled substations.


  • Combined phase and neutral overcurrent protection

Product benefits

  •  Protection for a variety of power distribution applications

Product features

  • Phase and neutral overcurrent protection relay for distribution feeders
  • Three-phase overcurrent protection with three stages: I>, I>> and I>>>
  • Non-directional earth-fault protection with sensitive low-set stage I0> and additional high-set stage I0>>
  • Phase discontinuity protection for detection of the loss of one phase or severe phase unbalance
  • Integrated circuit-breaker failure protection for enhanced system reliability
  • Improved system reliability supported by a built-in self-supervision system with auto-diagnosis
  • Serial communication capability for extensive exchange of data between the protection relay and the substation control level

Are you looking for support or purchase information?

Loading documents

Related offering

Select region / language