General technical data
Ferrite technology from Kabelwerk Eupen
Cables and wires play a major role in the coupling and transmission of disturbance variables in electronic devices. Kabelwerk Eupen took this fact as an opportunity to develop and produce ferrite-coated cables.
The basis of this technology is a high-quality ferrite-based layer. A special mixture was developed, composed of a polymer material to which a considerable amount of ferrite (up to 90%) is added. The mixture is applied to copper conductors by extrusion and is called EMC/COM.
The ferrite layer is not electrically conductive; it has very interesting magnetic properties. Because ferrite is a ferromagnetic material, it is constantly remagnetized in an alternating magnetic field. The magnetization follows a hysteresis loop, and with each cycle energy is extracted from the electromagnetic field, which is released again as heat. This process increases steadily with frequency. The ferrite layer on a conductor causes higher frequencies to be strongly attenuated because most of their energy is absorbed in the ferrite layer. This applies both to high-frequency interference traveling on the conductor, which should not disturb the surrounding area, and to interference occurring in the surrounding area, which should not affect the signal on the cable.
The attenuation thus caused is always proportional to the cable length.
Interference immunity has been a topic that responsible developers and system administrators have to deal with not only since the EMC regulations became fully effective on 01.01.1996. Not only the security of important data, but also the reaction to the increased EMC awareness of your customers forces you to rethink. Cables with the ferrite (EMC/COM) coating are therefore effective aids for increasing interference immunity.
Principle structure of ferrite (EMC/COM) - coated cables and wires
The different cable types can be divided into two categories. On the one hand there are the so-called low-pass cables (LP cables), and on the other hand the so-called CMS cables.
The LP cables get their low-pass properties from their EMC/COM ferrite coating, where each individual conductor is coated with a ferrite layer. This means that the cable allows low frequencies to pass (DC voltage, AC voltage, wired communication frequencies) and blocks high frequencies (e.g. radio interference frequencies).
In CMS cables, the ferrite layer is applied over the shield.
LP / Low Pass - Cable
Typical applications: Mains power cable
Overview of ferrite coated cables and wires
- Insulated stranded wires with ferrite coating for interference-resistant wiring of control cabinets and electronic devices.
- Low-pass power cables(LP cables) for connecting sensitive equipment to the mains. The cables provide both an increase in immunity to electromagnetic interference on the network and a reduction in electromagnetic emission.
- Cables for connecting measuring sensors. Due to their very low working voltage, sensors are very sensitive to interference from the environment and are therefore preferably connected via ferrite-coated cables.
- Cables with attenuation of sheath currents (CMS cables), particularly suitable for connections subject to electromagnetic interference radiation.
- Motor connection cables for frequency converters, which prevent the very steep pulses of the converter from disturbing the environment. Also, the steep pulses are flattened by these cables, avoiding winding damage in the motor.
- Shielded cables for domestic installations that attenuate not only high frequencies but also low frequency magnetic fields (e.g. 50 Hz mains frequency or 16 2/3 Hz from railroads).