What is the difference between a copper braid screening and an aluminium laminated foil screening?
Virtually all ÖLFLEX® connection and control cables are screened with tin-plated copper braiding. UNITRONIC® data cables are screened with copper braids and aluminium-laminated synthetic foils, which are generally wrapped around the core bundle in overlapping spirals. Some data cables, such as the UNITRONIC® Li2YCY PiMF or ETHERLINE® Cat.5, actually feature both an aluminium foil and an additional copper braid.
Copper braids primarily protect the cable against inductive coupling in the low frequency range in which virtually all connecting and control cables operate. If, for example, a UNITRONIC® data cable is installed in the direct vicinity of an ÖLFLEX® connecting cable that may not have copper screen braiding, the data cable should be protected against inductive interference from the connection cable by means of a screening braid. The same applies if a connecting cable is installed in the proximity of an insufficiently shielded or EMC-compliant machine or in the vicinity of an electric motor, which can also generate fields of inductive interference.
Aluminium foils are primarily used in data cables, as data is generally transferred at very high frequencies, thus necessitating protection against capacitive coupling.
The so-called coupling resistance and the transfer impedance act as indicators of the shielding performance – the lower the measured transfer impedance, the greater the effectiveness of the cable screening.