Example 7: tested! EMC tests

The "electromagnetic compatibility" of Chainflex® cables

The subject of "electromagnetic compatibility (EMC)" is becoming increasingly important. This is due, in part, to an increase in electromagnetic interference fields over long distances; caused by modern telecommunications, communication technology, and energy technology.

The requirements for data transmission are also increasing. Signals are becoming more susceptible to interference from diverse electromagnetic influences in the local environment. This can be especially problematic for cable coupling conducted on a parallel basis over a certain distance. A heavy-current cable with interference produces an electromagnetic field which will, in turn, interfere with another cable - normally a signal cable - and then cause cable-conductor interference there.

Several years ago, igus® introduced fiber-optic cables made of glass and suitable for the mechanical stresses involved in cable carrier applications. Even Chainflex® cables with conventional copper conductors were tested for electromagnetic compatibility in an extensive, application-oriented test program.

In one test, an asynchronous motor was connected via an unshielded, heavy-current cable (Chainflex® CF30) to a frequency converter. On a parallel basis with this heavy-current, Chainflex® CF12 cables were kept available for digital signal transmission inside a cable carrier.

Chainflex® CF12 cables were specifically designed according to EMC standards and possess twisted-pair cores, the pairs of which have a copper shield, as well as a total shield made of a steel braid. Interference over a broad frequency range can be effectively prevented as a result.

The capacitive as well as the inductive coupling was another thing tested. The test determined that - even when energy and signal cables touch one another over a longer distance - error-free data transmission is possible if a shielded Chainflex® cable is used and this shield is grounded on both sides.

Tests were also carried out in accordance with standards on electromagnetic compatibility. These standards provide a general basis for determining the operating behavior of electrical devices repeatedly exposed to electrical interference. They were not introduced specifically for cables. In particular, tests with the burst generator were carried out. Here, fast transient interference signals are generated in pulse groups that simulate switching processes. Such processes occur during the interruption of inductive loads or during the bouncing of relay contacts, for example. Here, too, the shielded Chainflex® cables proved their reliability.