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Residual current device being highly sensitive, demands a low coercive and high permeable magnetic material. It should be able to sense all type of signals such as AC with variable frequency, pulsating half and full wave dc, mixed dc and pure dc etc. Conventional soft magnetic material which are used for current sensing, though have moderate to high permeability but are easily influenced with the variation in frequency and temperature. This demerit makes the material not suitable for B & B+ type RCD application. The paper discloses about the property of a nano-crystalline magnetic material which has very low silicon content and high percentage of iron. Its grain size is in nano scale and its lattice structure is with reduced degree of freedom for anisotropy formation, thus making the material thermally stable. Due to above property the coercivity, core loss is very low and that of permeability, Curie temperature is very high and is independent of frequency variation. Hence is mostly suitable for residual current device application. The later part of the paper reveals about the Multiphysics modeling of a CBCT with conventional & nano-crystalline magnetic material. The nodal and vector analysis shows that the output characteristic of nano-crystalline magnetic material core is quiet stable with frequency, operating temperature and ageing variation as compared to conventional material. |
