Operating Manual

IRS31Pro-UMB Operating Manual V10 / 01.2020
G. Lufft Mess- und Regeltechnik GmbH 15
7.2.1 Extending the Supply Cable (e.g. 100 m)
Important: The original cable must be shortened after the shortest possible distance (curbside 5 m) and
extended from there. The loop impedance of the entire cable must not exceed 10 Ω.
Figure 4: Cable Extension
Example: Extension to 100 m with a 0.5 mm² cable with loop impedance of 73.2 Ω/km and parallel
connection of 4 wires in each case:
At 100 m the result per wire is a loop impedance of 7.3 Ω.
By connecting 4 wires in parallel the result is a loop impedance of 7.3 Ω / 4 = 1.83 Ω
Figure 5: Example of an Extension Box