Current measuring appliance for a length of cable.

摘要

The invention relates to a current measuring arrangement for a length of a power wire of a power cable (10) fed from one end, having two optical waveguide coils (42, 44) (Faraday coils) integrated in the power cable and having devices (65), existing at one end (8) of the length of cable, for injecting and outputting and analysing optical signals. The current measuring arrangement consists of two optical waveguide coils (42, 44), one of which is wound tightly and the other one of which is wound loosely. The tightly wound optical waveguide coil (42) is arranged at the injection end (8) of the length of cable (KS). The operating current (I) in the length of cable (KS) can be measured with both Faraday coils (42, 44). If there is no fault in the length of cable, the measurement quantity of both Faraday coils is zero. If there is a fault (short-circuit to earth), a finite angular rotation of the plane of polarisation is produced. The current measuring arrangement (42, 44) allows the fault current intensity (IF) and the relative fault current location (z/L) to be measured with respect to the length of the distance (L) in lengths of cable fed at one end.