Feb 2013
Electricity Distribution
Ground Mounted Fault Passage Indicator
Feb 2013
Northern Powergrid
Chris Goodhand, Innovation Manager (01977 605641)
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Innovation Funding Incentive
High Voltage Technology
The development of a new type of fault passage indicator that is intended to measure the magnetic field strength associated with each phase conductor in a three phase cable to give an indication of both phase to phase and phase to earth faults. The device is intended to use three magnetic field sensors placed around a trefoil cable in close proximity to each phase core. The device is intended to overcome the problems associated with earlier types of fault passage indicators, namely:

  • They only provide earth fault indication

  • They are difficult to retrofit to existing switches

  • Issues of unreliability where split-core current transformers have been used

Many of those presently in service require a manual re-set following fault detection (this has been overcome by more modern types but the retrofit problems remain).

The projects aims to correlate the externally detected magnetic fields around a three phase cable to the positive, negative and zero sequence currents within the phase conductors, thereby determining fault types.