Moreover,because normal optical fibers are cut off also the blocked time of the optical fiber system and the loss of the normal fibers are artificially increased,thereby causing so-called "non-breakdown blockage".

To avoid losing both money and commodities, it is veryurgent for one party to prevent acceptance of active risk or accidental risk from another.

Combined with the research status of single-phase-to-ground fault locating for small current grounding system,a new idea based on non-fault-phase transient current is presented.