Rockwell Automation 1746-NR4 SLC RTD/Resistance Input Module User Manual - Manual (Page 121)

Publication 1746-UM008B-EN-P - December 2006
Specifications 121
When you are using 100
Ω or 200 Ω platinum RTDs with 0.5 mA
excitation current, refer to the following important note about module
accuracy.
Copper (426)
(1)(2)
10
Ω
Not allowed.
(5) ±0.6 °C
(±1.1 °F)
Not allowed. ±0.017 °C/°C
(±0.031 °F/°F)
Nickel (618)
(1)(3)
120 Ω ±0.2 °C
(±0.4 °F)
±0.2 °C
(±0.4 °F)
±0.008 °C/°C
(±0.014 °F/°F)
±0.008 °C/°C
(±0.014 °F/°F)
Nickel (672)
(1)
120
Ω
±0.2 °C
(±0.4 °F)
±0.2 °C
(±0.4 °F)
±0.008 °C/°C
(±0.014 °F/°F)
±0.008 °C/°C
(±0.014 °F/°F)
Nickel Iron (518)
(1)
604
Ω
±0.3 °C
(±0.5 °F)
±0.3 °C
(±0.5 °F)
±0.010 °C/°C
(±0.018 °F/°F)
±0.010 °C/°C
(±0.018 °F/°F)
(1) The digits following the RTD type represent the temperature coefficient of resistance ( ∝), which is defined as the resistance change per ohm per °C. For instance, Platinum
385 refers to a platinum RTD with ∝ = 0.00385 ohms/ohm -°C or simply 0.00385 /°C.
(2) Actual value at 0 °C (32 °F) is 9.042 Ω per SAMA standard RC21-4-1966.
(3) Actual value at 0 °C (32 °F) is 100 Ω per DIN standard.
(4) The accuracy values assume that the module was calibrated within the specified temperature range of 0…60 °C (32…140 °F).
(5)
To maximize the relatively small RTD signal, only 2 mA excitation current is allowed.
(6) Temperature drift specifications apply to a module that has not been calibrated.
RTD Accuracy and Temperature Drift Specification
RTD Type
Accuracy
(0.5 mA Excitation)
(4)
Accuracy
(2.0 mA Excitation)
(4)
Temperature Drift
(0.5 mA Excitation)
(6)
Temperature Drift
(2.0 mA Excitation)
(6)
IMPORTANT
Module accuracy, using 100
Ω or 200 Ω platinum RTDs with 0.5
mA excitation current, depends on the following criteria:
• Module accuracy is ± 0.6 °C after you apply power to the module or
perform an autocalibration at 25 °C (77 °F) ambient with module
operating temperature at 25 °C (77 °F).
• Module accuracy is ± (0.6 °C + DT ± 0.034 °C/°C) after you apply
power to the module or perform an autocalibration at 25 °C (77 °F)
ambient with the module operating temperature between 0…60 °C.
Where DT is the temperature difference between the actual
operating temperature of the module and 25 °C (140 °F) and 0.034
°C/°C is the temperature drift shown in the table above for 100
Ω or
200
Ω platinum RTDs.
• Module accuracy is ± 1.0 °C after you apply power to the module or
perform an autocalibration at 60 °C (140 °F) ambient with module
operating temperature at 60 °C (140 °F).