Modules
33
nVision Operation Manual
Logging Interval
Fastest Logging Interval . . . . . . . . . . 5 readings per second.
Note:
Although the nVision logging interval may be set to a faster rate, the RTD100 module will update the reading at 5 times per second.
ATEX and IECEx Scheme Entity Parameters
The RTD100 module has these specific input entity parameters:
Ui = 0
Uo = 9.73 V
li = 0
lo = 1.6642 A
Pi = 0
Po = 1.1 W
Co = 0.5 uF
Lo = 12 uH
*
*
Total cable inductance between all modules
RESISTANCE TEMPERATURE DETECTORS (RTD)
Resistance Temperature Detectors (RTDs) are temperature sensors that contain a resistor that utilize the predictable change in electrical resistance of particu-
lar materials over temperature. Platinum elements have been used for many years in laboratories and industrial processes, and have a reputation for range,
linearity, repeatability, and stability. The selection strengths of RTDs, or sometimes called PRT (platinum resistance thermometer) are their wide temperature
range (approximately -200 to 850ºC), accuracy (better than thermocouples), good interchangeability between similar sensors, and long-term stability.
Callendar-Van Dusen Equation
The relationship between temperature and resistance is given by the Callendar-Van Dusen equation.
RT = R0 [1 + AT + BT
2
+ CT
3
(T-100)] for (-200°C < T < 0°C)
RT = R0 [1 + AT + BT
2
] for (0°C ≤ T ≤ °C of Upper Temperature Range listed below)
Where: RT = the resistance at temperature, T; R0 = the resistance at 0°C; and the constants A, B, and C dependent upon RTD selected (TCR).
nVision (TCR)
Temp. Coefficient of
Resistance
Temperature
Range
Base
Resistance
TCR (Ω/Ω/ºC)
Sensitivity
(avg. Ω/ºC,
0 to 100 ºC)
A (°C-1)
B (°C-2)
C (°C-4)
Pt100 (385) Euro
-200 to 850ºC
(-328 to 1562ºF)
100Ω at 0ºC
0.00385
0.385
3.9083 x 10
-3
-5.7750 x 10
-7
-4.183 x 10
-12
Pt100 (3926) US
-259 to 1235ºC
(-434 to 2255ºF)
100Ω at 0ºC
0.003926
0.3926
3.9848 x 10
-3
-5.87 x 10
-7
-4.0 x 10
-12
Pt100 (3911)
-259 to 630ºC
(-434 to 1166ºF)
100Ω at 0ºC
0.003911
0.3911
3.9692 x 10
-3
-5.8495 x 10
-7
-4.2325 x 10
-12
