Simple fault path indication techniques for earth faults

Matti Lehtonen, Osmo Siirto, Mohamed F. Abdel-Fattah

Research output: Chapter in Book/Report/Conference proceedingConference contributionScientificpeer-review

14 Citations (Scopus)


Fault indication is the key element in any fault management system. In case of short circuits, fault indication is straightforward, but especially in ungrounded and compensated neutral networks, the single phase fault currents are typically so small that simple fault current threshold detection hardly gives any satisfactory results. The problem can be solved by combining neutral voltage measurement to the sum current measurement using directional relay characteristics. However, the requirement of both current and voltage measurements makes the solution cost prohibitive especially when retrofitting in the existing secondary substations. Hence, there is the need for a simple but reliable earth fault indicator which is based on current measurements solely. This paper takes the above mentioned challenge and compares a number of possible fault indication solutions which are using local current measurements at the secondary substations only. The methods presented use either the sum current measurement directly, or are based on the comparison of the measured phase currents using symmetrical components.

Original languageEnglish
Title of host publication9th International: 2014 Electric Power Quality and Supply Reliability Conference, PQ 2014 - Proceedings
Number of pages8
ISBN (Print)9781479950201
Publication statusPublished - 2014
MoE publication typeA4 Article in a conference publication
EventElectric Power Quality and Supply Reliability Conference - Rakvere, Estonia
Duration: 11 Jun 201413 Jun 2014
Conference number: 9


ConferenceElectric Power Quality and Supply Reliability Conference
Abbreviated titlePQ


  • Earth fault
  • fault indication
  • unearthed and compensated neutral and medium voltage cable networks


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