Transmitter-Sensor Matching - Emerson Rosemount 648 Reference Manual

Reference Manual
00809-0200-4648, Rev BB
2.8.2

Transmitter-sensor matching

Fast Key sequence
Perform the transmitter-sensor matching procedure to enhance the temperature
measurement accuracy of the system (see the comparison below) and if you have a sensor
with Callendar-Van Dusen constants. When ordered from Emerson Process Management,
sensors with Callendar-Van Dusen constants are NIST-traceable.
The Rosemount 648 Wireless accepts Callendar-Van Dusen constants from a calibrated RTD
schedule and generates the actual curve to match that specific sensor curve.
1. The Actual Curve is identified from the Callendar-Van Dusen equation.
Standard RTD
Rosemount 648 Wireless
Standard RTD
Total System
1. Calculated using root-summed-squared (RSS) statistical method.
Total System Accuracy = ( Transmitter Accuracy)
Callendar-Van Dusen equation
R = R + R
t o
The following input variables, included with specially-ordered Rosemount temperature
sensors, are required:
R = Resistance at Ice Point
o
Alpha = Sensor Specific Constant
Beta = Sensor Specific Constant
Delta = Sensor Specific Constant
Configuration
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2, 1, 1
Actual Curve
Standard IEC 751
"Ideal" Curve
0 °C
Temperature, C
System accuracy comparison at 150 °C using a PT 100 (A=0.00385)
RTD with a span of 0 to 200 °C
±0.45 °C
±1.05 °C
(1)
±1.14 °C
[t - (0.01t-1)(0.01t) - (0.01t - 1)(0.01t)
o
(1)
Matched RTD
Rosemount 648 Wireless
Matched RTD
(1)
Total System
2
+ (Sensor Accuracy)
3
]
Configuration
July 2016
±0.45 °C
±0.018 °C
±0.048 °C
2
19