KEMET offers the following ESD/EMI Cores for round and flat cable.
Turns and Impedance Characteristics
When the desired performance of an EMI core cannot be obtained with a single pass through the core, the impedance characteristics can be changed with multiple turns.A turn is counted by the number of lead-wire windings which pass through the inner hole of the core. Windings on the outside of the core do not count.Adding turns will result in higher impedance while also lowering the effective frequency range.
Core Material and Effective Frequency Range
There are two ferrite material options for KEMET EMI Cores: Nickel-Zinc (Ni-Zn) and Manganese- Zinc (Mn-Zn). Each core material has a different resistance and effective frequency range. The Mn-Zn core material has lower resistance compared to the Ni-Zn; therefore, be sure to provide adequate insulation before use.For reference, the Ni-Zn core material is typically effective for the frequencies in the MHz band range such as the FM-band, while the Mn-Zn core material is typically effective for the kHz band range such as the AM-band.It is recommended to verify actual effectiveness in the target application with measurements.