Application Current transformers can convert large currents into small currents in a certain proportion, thereby providing current for various instruments and relay protection, and isolating the secondary system from high voltage. This way can protect workers and equipment, can also simplifies and standardizes the manufacture of meters and relays. Advantages In order to improve the current transformer precision, has to improve the magnetic permeability of current transformer cores. Compared with silicon steel core, nanocrystalline core has better magnetic permeability. Compared with permalloy core, the cost of nano core is lower. So nano core is the ideal material of current transformer. It is widely used in precision current transformer, zero sequence current transformer, medium and high frequency transformer.