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Electromagnetic Interference

Understanding EMI involves the analysis of electromagnetic pollution between a source of disturbance and its victim.

THE EMI

Electromagnetic interference is emitted by a source polluting a victim. Electromagnetic interference is transmitted by a process known as coupling. An EMI problem only occurs when the three elements source, coupling and victim are evident. To obtain a good EMI we simply need to eliminate one of the three elements or reduce its effect.

Metallic cable trays with excellent electrical continuity which are integrated into an installation's equipotential earthing network reduce the effects of coupling and therefore improve an electrical installation's EMI.

Define EMI
THE CABLOFIL SOLUTION
  • It's open structure makes it easy to ensure correct separation by visual inspection.
  • It's easy installation and metal structure guarantee excellent electrical continuity in all cases: couplings, bends, level changes, crossing walls, etc.
  • It's open structure can reduce crosstalk.
BEST PRACTICES FOR REDUCING EMI
* BICSI Standard specifies how far cables must be kept apart. This depends on the type of data cable, the number of power cables and the type of cable tray. Otherwise, the distance of 8" provides a simple and sensible rule of thumb. For precise details, please contact our technical support service.
EMC TESTS

Tests conducted by the accredited and independent AEMC Measures and CETIM laboratories demonstrate the performance of CABLOFIL in regard to the EMI of the electrical installation.

When integrated into the earthing network, CABLOFIL's metallic cable trays help electrical installations achieve excellent EMI levels.
DATA CABLE IN AN EXTERNAL ELECTROMAGNETIC FIELD

A data cable (Category 5e UTP) is placed in an insulated anechoic chamber and subjected to a powerful artificially-generated electromagnetic field in order to simulate electromagnetic interference.

Results and interpretations

A simple comparison of the measurements for the different cable tray configurations (wire mesh and perforated tray, with and without cover) makes it possible to quantify the role played by the tray in terms of EMI.

These tests show that there is no significant difference in >>Faraday cage<< effect offered by wire mesh or perforated cable tray.

These results show that it is vital:

  • Use metal tray
  • Earth the cable tray
  • Use a cover if required

Non metallic and non-ferrous cable trays (PVC, Aluminum composite materials) are ineffective against electromagnetic interference.

DATA CABLE ALONGSIDE A POWER CABLE

Results and interpretations

A Category 6 UTP data cable is placed inside an insulated anechoic chamber and subjected to an electromagnetic field generated by a power cable. The following parameters are studied:

  • Cable-tray earthing
  • Separation distances: 0, 4", 8", 12"
  • Cable-tray type: wire mesh, perforated tray, trunking
  • Separated cable trays
  • One cable tray, with and without dividers

As a result, a total of 118 configurations are tested.

Electromagnetic Interference
Electromagnetic Interference

Results and interpretations

This second test configuration confirms that metal cable trays reduce interference (wire mesh or perforated tray).

To obtain a good EMI, these results show that it is vital:

  • Use metal cable tray
  • Earth the cable tray

  • Ensure maximum separation distances
  • Use two separate cable trays for power and data
  • Use a divider if sharing containment systems

Never put power cables and data cables in the same closed compartment.