Preparations for Inteference-free Operation

In the following section we have compiled some general information for you that is important for inteference-free operation.

Cable routing

Route your cables separately in cable groups. This will protect your gateway from any unintended electromagnetic interferences.

The following groups should be routed separately from each other:

Group Cable
A Data and power supply lines for:

DC voltage below 60 V

AC voltage below 25 V

B Data and power supply lines for:

DC voltage between 60 V and 400 V

AC voltage between 25 and 400 V

C Power supply lines above 400 V

You can route cables of the same group together in cable ducts or bundles.

Cables of group A and B:

  • Route the groups in separate bundles or
  • in cable ducts at a minimum distance of 10 cm from each other.

Cables of group C

  • Route the groups in separate bundles or
  • in cable ducts at a minimum distance of 50 cm from the other groups.

Shielding

Shield your cables. This will reduce any unintended electromagnetic interferences.

You can find further information on this topic in the specifications for your fieldbus.

Potential equalization

Potential differences occur when devices are connected to different earths. These potential differences cause malfunctions.

To prevent malfunctions, you have to route an equipotential equalization conductor.

When doing so, bear in mind the following points:

  • Select an equipotential equalization conductor with low impedance.
  • Select the following as a reference value for the cross-section of the potential equalization cable:
  • 16 mm2 for potential equalization cables of up to 200 m in length
  • 25 mm2 for potential equalization cables of more than 200 m in length
  • Use potential equalization cables made of copper or galvanized steel.
  • Connect potential equalization cables extensively with the earth rail.
  • The smallest surfaces possible should be sandwiched between potential equalization cables and signal cables.

If the devices of the control system are connected by shielded signal cables that are earthed on both sides, the impedance must be 10% of the shielding impedance.