Pathfinder MK9B

Portable Pathfinder for 11 & 33kV networks with SEF detection capability

The Pathfinder MK9B builds upon the MK8's success by detecting very low-value Sensitive Earth Fault (SEF) faults using two parallel algorithms. It identifies fault currents above 15 Amps lasting longer than 50 milliseconds (Normal-Red flag) and detects currents ranging from 3 to 15 Amps with a duration over three seconds (SENSITIVE EARTH FAULT-YELLOW flag). This empowers fault engineers with enhanced fault information and precise location capabilities for low-value faults.


  • The Pathfinder MK9B expands on the success of the MK8 by incorporating two parallel algorithms for detecting low-value SEF faults.
  • The MK9B follows the MK8's approach of identifying fault currents above 15 Amps lasting longer than 50 milliseconds, indicated by the Normal-Red flag.
  • In addition, the MK9B can detect currents between 3 and 15 Amps with a duration exceeding three seconds, triggering the SENSITIVE EARTH FAULT-YELLOW flag.
  • The inclusion of these algorithms provides fault engineers with comprehensive fault information and enables the precise location of very low-value faults.
  • The instrument features a single switch for convenient on/off operation and performs a battery test by sequentially flipping each flag before returning them to their default state.
  • The MK9B is designed to respond to both earth fault and phase-to-phase faults.
  • It is mounted at eye level on the supporting pole for ease of access and visibility.
  • Rigorous testing conducted at PNDC Strathclyde has confirmed the MK9B's ability to detect low-value currents and highlighted its remarkable stability even beyond faults or in spur lines without any faults.