Are all EMC cables multi-core?

[marko333]

Hello all!

Are all EMC cables multicore?

Im not entirely sure how an EMC cable works, but can you have several single core cables per phase running from a VSD to a motor that are EM sheilded? Or do you have to use several multi-core cables that are connected in some special formation?

Thankyou,

Makro

 

[jbartos]

Suggestion: More info is needed regarding any industry standards that might be followed.
Visit

http://www.electronicstalk.com/news/har/har101.html

http://www.eupen.com/images/downloads/divers/Freco.ppt

etc. for more info

 

[Skogsgurra]

marko333,

The term "EMC cable" is not very well defined. But when it is being used with VFDs it usually means a cable with a dense shield (usually better than 85 % coverage) and sometimes "distributed PE" so that the return path for capacitive leakage currents has the lowest pssible impedance. Low PE impedance is important to avoid "frame voltage" caused by HF return currents.

It is also important that you use all metal cable glands and that they connect 360 degrees around the cable and also that they connect well to cabinet walls (no paint!) and motor connection box (again, no paint!).

Have a look at Belden's site. They show some special cables for VFD applications. ABB has a set of Technical Guides that deal with VFD installations. A lot of information there. Look for "Technical Guide" when you visit their page.