Magneto-optical current measuring devices

Abstract

Abstract 1477688 Current measuring SIEMENS AG 7 Aug 1974 [17 Sept 1973] 34729/74 Heading G1A A magneto-optical current measuring device comprises a magneto-optical body containing a first magnetically saturable part 2, Yttrium-Iron garnet, and a further part 3, Gadolinium-Gallium garnet, which has a diamagnetic or a paramagnetic property in order continue to provide a response in the event of an overload producing an excess current and magnetically saturating the first part 2. The current measuring device is of the type wherein a current to be measured is passed through a winding to produce a magnetic field and influence a Faraday rotor 1 through which a beam of polarized light 10, 20 is passed. The beam is multiply reflected by reflective surfaces 4&5 before it emerges after having undergone same Faraday rotation, from 11 to 21, in dependence upon the strength of the magnetic field produced by the current to be measured. The Faraday rotor may be made such that the magnetic field produced by a given current at the mid point of the measuring range produces a field equal to half the magnetic saturation field strength of the first part 2 of the magneto-optical body. The description refers to using the invention in a protective transducer arrangement in a normal Faraday rotation current measurement circuit to activate a protective switch when the current gets too high.

Inventors

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Bibliographic Details