Emerson Rosemount 648 Reference Manual page 25

Reference Manual
00809-0200-4648
Figure 2-14: Standard vs. Actual Sensor Curve
*The Actual Curve is identified from the Callendar-Van Dusen equation.
System accuracy comparison at 150 °C using a PT 100 (A=0.00385) RTD with a span of 0 to
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
t
The following input variables, included with specially-ordered Rosemount temperature
sensors, are required:
R = Resistance at Ice Point Alpha = Sensor Specific Constant Beta = Sensor Specific
o
Constant Delta = Sensor Specific Constant
To input Callendar-Van Dusen constants, perform the following procedure:
Procedure
1. From the Home screen, select 2 Configure → 1 Guided Setup → 1 Configure
2. Select Cal VanDusen at the Select Sensor Type prompt.
3. Select the appropriate number of wires at the Select Sensor Connection prompt.
4. Enter the R
5. Select desired other options and select Enter.
Rosemount 648 Wireless
Actual Curve
Standard IEC 751
"Ideal" Curve*
0 °C
Temperature, °C
(1)
+ R [t - δ(0.01t-1)(0.01t) - β(0.01t - 1)(0.01t)
o oα
Sensor → 1 Configure Type and Units and press Enter.
, Alpha, Delta, and Beta values from the stainless steel tag attached to
o
the special-order sensor when prompted.
200 °C
Matched RTD
±0.45 °C Rosemount 648 Wireless
±1.05 °C Matched RTD
±1.14 °C Total System
2
+ (Sensor accuracy)
3
]
Configuration
May 2020
±0.45 °C
±0.18 °C
(1)
±0.48 °C
2
25