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Example 7: tested! EMC tests

The "electromagnetic compatibility" of chainflex® cables

 

The subject of "electromagnetic compatibility (EMC)" is becoming increasingly important. For one thing, this is due to a increase in the electromagnetic interference fields in the long-distance range caused in particular by modern telecommunications and communication technology as well as in the local range caused by energy technology.

On the other hand, the requirements for data transmission are also increasing. The signals are becoming more susceptible to interference and the electromagnetic environmental influencing factors more diverse. This can be especially problematic for the coupling between cables which, as is frequently the case in energy-conducting chains, are conducted on a parallel basis over a certain distance. A heavycurrent cable with interference acts as a producer of an electromagnetic interference field which, in turn, acts upon another cable, normally a signal cable, and then causes cableconducted interference there.

Already several years ago, we therefore introduced electrical cables with fiber-optic cables made of glass that are also capable of being subjected to the mechanical stress in Energy Chains®. Even the chainflex® cables with conventional copper conductors were tested with respect to their electromagnetic compatibility in an extensive, application-oriented test program.

An asynchronous motor, for example, was therefore connected via an unshielded heavy-current cable (chainflex® CF30) to a frequency converter. This frequency converter with pulse width modulation becomes the generator of new spectral shares never existing previously in the primary or secondary networks. On a parallel basis with this heavy-current, chainflex® cables were also kept available for digital signal transmission in energy chains. Especially good results can be achieved here by the chainflex® CF12 cable which was specifically designed according to the EMC aspect. This cable possesses twisted-pair cores, the pairs of which are provided with a copper shield, as well as a total shield made of a steel braid in addition. Interference over a broad frequency range can therefore be effectively prevented as a result.

The capacitive as well as the inductive coupling was also tested. In the case of the selected test conditions, it was determined that, even when the energy cables and signal cable 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.

In addition, tests were carried out in accordance with the existing standards on electromagnetic compatibility. These standards provide a general basis for determining the operating behavior of electrical devices that are 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 in particular. Such processes occur, e.g. during the interruption of inductive loads or during the bouncing of relay contacts. Here, too, the shielded chainflex® cables have proved their reliability.

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