What is the maximum cable length available for an Exi certified sensor?
Answer:
It depends on the output signal of the sensor and values on the Exi certificate:
Example with our certificate ISSeP07ATEX012X:
- Non-amplified output (Wheatstone bridge – mV/V): Options I4 or I6
Our certificate ISSeP07ATEX012X specifies that:
- The capacitance of the cable may not exceed 14 nF
- The inductance of the cable may not exceed 10 µH
The capacitance of our standard cable (4 wires) is 130 pF / m, its inductance 0.7 µH / m. The maximum length is in this case 14 m because we then reach the maximum inductance.
2. Current output (4…20 mA – 2 wires) : Option C6
In this case, the same certificate specifies that:
- The capacitance of the cable may not exceed 53 nF
- The inductance of the cable may not exceed 150 µH
The capacitance of our standard cable (2 wires) is 150 pF / m, its inductance 0.65 µH /m. The maximum length is in this case 230 m because we then reach the maximum inductance