Published on 07 Jun 2019 by Lana Hajovsky
The use of multi-polar cables for connecting field devices is quite common and is accepted by the standard if in the safety analysis of a system the opening, short circuiting, and grounding of the cable are considered as probable situations and not counted as faults.
Example of a connection with multi-polar cables:
In the example shown above, the multi-polar cable includes different intrinsically safe circuits. An eventual damaging of the cable could short circuit wires of different circuits; therefore,voltages can be present or currents can circulate in HAZARDOUS LOCATIONS, both of which are larger than those for each single circuit.
Practically, the analysis on the effect of accidental contacts is similar to the one used in evaluating the barrier combination.
It must also be said that the fault modalities of the considered cable depend on the type of cable used and are specified in the EN 50.039 standard regarding intrinsically safe systems.