Study Of The Rare Earth Giant Magnetostrictive Current Transformer

Giant Magnetostrictive Material (GMM) is another new function material together with rare earth permanent magnetic material,rare earth element luminescent material and high temperature supercoducting material. In the action of definite magnetic field GMM has awfully lardge length or bulk transformation compared with traditional nickel group and iron group magnetostrictive material, it's magnetostrictive coefficient can reach 2500ppm.In this paper, the author put forward a new train of thoughts to design electronic Current Transformers; namely, applied GMM in electronic Current Transformers. The basic idea of this design is: when in the action of magnetic field, the length of the GMM stick will chang, the output light from the fiber-optic sensing probe ( single mode pigtail + Grin-lens ) be reflected by one side of GMM and entered into fiber-optic sensing probe second time, the light force will be modulated, then the output power will change. When deal with the output light through photoelectric conversion and other relative disposal, we can know the electric current loaded in the drive winding from the output voltage and then realized real time supervise the exterior current.In this paper, the author presented two schemes of the current transformer, photoelectricity mode and all-optical mode; designed the related parameter of the inspired magnetic field and bias magnetic field; Analyzed the sensing part, photoelectric conversion part, and give the in-out characteristic curve of the two systems; finally, cometo the conclusion that all-optical mode current transformer has definite practical use.The fiber-optic sensing probe and photoelectric conversion parts also can realize themicro displacement test, this is a new method to test the micro displacement, it has many merits such as has a high precision and good reliability and so on.