23
5 Lines
An almost constant error is produced with two-wire circuits depending on the stranded wire cross section
and the line length. This error can be corrected at the evaluation unit (by using zero point correction, for
example). However, the resistance of the connection line also depends on the temperature. This addi-
tional influence cannot be taken into account.
chapter 3.5 "Circuit types", Page 16
The following table can be used to estimate the measurement errors for copper stranded wires:
The measurement error depends on the construction of the stranded wire, the surface, etc. The specified
values are therefore average values for copper stranded wires at room temperature.
A loop resistance (Ω/m) can also be estimated for stranded wires made of thermal material for thermo-
couples (the specifications apply for room temperature):
Follow the relevant data sheets/drawings in individual cases
Cross section Measurement error per m of line (per loop)
in mm
2
Pt100 Pt500 Pt1000
0.14 0.64 K 0.08 K 0.06 K
0.22 0.41 K 0.07 K 0.04 K
0.25 0.36 K 0.05 K 0.04 K
0.34 0.26 K 0.04 K 0.03 K
0.50 0.18 K 0.03 K 0.02 K
0.61 0.15 K 0.02 K 0.01 K
0.75 0.12 K 0.13 K 0.01 K
1.00 0.09 K 0.02 K 0.01 K
Cross section Thermocouple Resistance Loop resistance (2 conductors)
in mm
2
Pt100 in Ω/m in Ω/m
0.22 Fe 0.5 2.5
CuNi 2.0
NiCr 3.3 4.5
Ni 1.2
0.5 Fe 0.25 1.25
CuNi 1.0
NiCr 1.45 2.0
Ni 0.55
PtRh 0.07 0.2
Pt 0.13
1.5 Fe 0.08 0.42
CuNi 0.34
NiCr 0.5 0.7
Ni 0.2
PtRh 0.025 0.07
Pt 0.045
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