Fig. 10 Diagram For Basic Accuracy For Pt1000, 3-Wire Connection; Fig. 11 Diagram For Basic Accuracy For Pt1000, 4-Wire Connection - Beckhoff EPP3504-0023 Short Manual

Product overview
• Pt1000 according to DIN EN 60751/IEC751 with α= 0.0039083 [1/C°]
RTD temperature measurement
Electrical measuring range used
Starting value
End value
PDO LSB (legacy range only)
Basic accuracy: measurement deviation
at 23 °C ambient temperature, with
averaging, typ.
2)
Temperature coefficient , typ.
2
) The temperature coefficient, i.e. the change in the measured temperature value in relation to the change in
the ambient temperature of the box module, is not constant, as can be seen in the following plot. The value
at a sensor temperature of 0 °C is given here as an orientation value. Further values can be taken from the
plot.
Basic accuracy for Pt1000, 3-wire connection:
Fig. 10: Diagram for basic accuracy for Pt1000, 3-wire connection
Basic accuracy for Pt1000, 4-wire connection:
Fig. 11: Diagram for basic accuracy for Pt1000, 4-wire connection
If further specification data are of interest, they can or must be calculated from the values given in the
resistance specification.
The sequence:
• General: The conversion is explained here only for one measuring point (a certain input signal); the
steps simply must be repeated in case of several measuring points (up to the entire measuring range).
• If the measured resistance at the measured temperature measuring point is unknown, the measured
value (MW) in [Ω] must be determined:
MW = R
Measuring point
• The deviation at this resistance value is calculated
◦ Via the total equation
◦ or a single value, e.g. E
◦ the measurement uncertainty in [Ω] must be calculated:
E (R
Resistance Measuring point
or: E (R
Resistance Measuring point
or (if already known) e.g.: E
• The slope at the point used must then be determined:
ΔR (T ) = [ R(T
proK Measuring point
with the help of an R→T table
• The temperature measurement uncertainty can be calculated from the resistance measurement
uncertainty and the slope
E (R ) = (E
Temp Measuring point
• To determine the error of the entire system consisting of RTD and the measuring device in [°C], the
two errors must be added together quadratically:
28
Pt1000 2-wire
2 kΩ
-200°C ≈ 185.2 Ω
266°C ≈ 2000 Ω
0.1/0.01/0.001°C/digit, depending on PDO setting
The achievable measurement
uncertainty, as a system side
offset, is essentially
dependent on the line
resistances and can at best
reach the value of the 3-wire
measurement.
(T ) with the help of an R→T table
Measuring point
= 15 ppm
Single FSV
) = E (R
Total Measuring point
) = E (R
Single Measuring point
(R
Resistance Measuring point
+ 1 °C) – R(T
Measuring point
(T )) / (ΔR
Resistance Measuring point
Pt1000 3-wire
< ±132 mK
(preliminary value)
< 6.6 mK/K
(preliminary value)
) ⋅ FSV
) ⋅ FSV
) = 0.03 Ω
)] / 1 °C
Measuring point
(T ) )
proK Measuring point
Version: 1.2
Pt1000 4-wire
< ±120 mK
(preliminary value)
< 5.4 mK/K
(preliminary value)
EPP3504-0023