When selecting a magnetic ring, two factors are mainly considered: the impedance characteristics of the magnetic ring and the interference characteristics of the filtered circuit.
In appearance, the preferred choice is "as long as possible, as thick as possible, as small as the inner diameter, as small as the inductance" magnetic ring. That is, the longer the magnetic ring, the better, and the more closely the aperture and the cable through the better.
One of the advantages of magnetic ring is that there is no electrical connection with the filtered circuit, nickel zinc ferrite or manganese zinc ferrite can be selected according to the frequency characteristics of interference signals. The high frequency characteristics of the former is better than the latter, the permeability of manganese zinc ferrite is thousands to tens of thousands, while that of nickel zinc ferrite is hundreds to thousands. The higher the permeability of magnetic ring ferrite, the greater the impedance at low frequency and the smaller the impedance at high frequency. Therefore, in the suppression of high frequency interference, it is appropriate to choose nickel zinc ferrite, on the contrary, manganese zinc ferrite.
It is not that the larger the impedance, the better the suppression effect of interference signals, because there is a parasitic capacitor on the actual magnetic ring. This parasitic capacitor is in parallel with the inductor, but when the high-frequency interference signals are encountered, this parasitic capacitor will short-circuit the inductance of the magnetic ring and lose its function. Generally, when the low-frequency end is disturbed, the cable will wind 2~3 turns. On the one hand, it can increase the area through the ring and increase the equivalent absorption length. On the other hand, it can make full use of the hysteresis characteristics of the magnetic ring and improve the low-end characteristics. When the high frequency end disturbs, the turns can not be wound (because of the existence of distributed capacitance), choose a longer magnetic ring.
The current through the magnetic ring is proportional to the volume of the magnetic ring, the imbalance between the two, easy to cause saturation, reduce the component performance, the effective way to avoid saturation is to put two wires of the power supply (V+, V or L, PE) through a magnetic ring at the same time.
Nanmagnetic spirit, closely follow the advanced technology, engaged in the research and development of products: RH magnetic ring, T magnetic ring, FS flat magnetic ring, UF assembled magnetic ring, BB ribbon magnetic beads, RID (double hole magnetic beads, six hole magnetic beads, small magnetic beads), KT * ring, KS (ferrosilicon aluminum, magnetic core) and other products.
About the number of turns: the more the number of turns, the better the effect of inhibiting low frequency interference, while the effect of inhibiting high frequency noise is weak. In practice, the number of turns of magnetic ring should be adjusted according to the frequency characteristics of disturbing current. When the frequency band of the interference signal is wide, two magnetic rings can be set on the cable, each magnetic circle around a different number of turns, so that a high frequency interference and low frequency interference can be simultaneously.
In addition, the appearance of the magnetic ring can be checked by visual inspection under normal lighting conditions, and the overall size can be checked by vernier caliper with accuracy of 0.02mm under normal lighting conditions.
The products of Zhijia magnetic industry are mainly used in: power cord, USB data cable, signal cable, flat screen cable, cable, electronic toys, electrical appliances, machinery, communication power equipment and high-tech products
