The Pathfinder MK9B continues the enormous success of the MK8 but now can detect very low value SEF faults, as a result of 2 algorithms running in parallel. The first follows that of the traditional MK8 in detecting fault current above 15 amps which have a duration longer than 50msecs. These faults will trip the NORMAL – RED flag. However, if a current of between 3 and 15 amps is detected and has a duration longer than 3 seconds the MK9B will trip the SENSITIVE EARTH FAULT – YELLOW flag. In this way the fault engineer will know more about the fault, and has the ability to locate very low value faults with confidence.
The single switch turns the instrument on/off and carries out a battery test by flipping each of the flags in turn before returning them to black. The MK9B will respond to both earth fault and phase to phase faults, and is mounted at eye level on the supporting pole.
Testing at PNDC Strathclyde has proven the principal of detection of low value currents, and just as importantly the stability of the MK9B beyond the fault or on a spur with no fault to remain untripped.