EI Core/ ferrite core / ferrite ei core General Description 1, MnZn/NiZn ferrite EI core is characterized by less core loss, high yield-resistance and high permeability, and ferrite EI core is easier to achieve high voltage electrical. 2, EI cores are used for voltage and current transformers. Applications include pulse transformers, telecommunication, broadband transformers, filters and inducing meters, and more. For more detail info, please feel free to visit our website or inquire us at any of your convenience.