Measurement Computing DataShuttle - Manual (Page 32)

2-14 DataShuttle - Technical Notes 11-13-01 DataShuttle and DynaRes
Thermocouple Conditions – Same as General Conditions. Does not include the accuracy of the
thermocouple itself (cold junction error must be added in; cold junction compensation with
DataShuttle-TCs only). Resolution assumes 12 bit resolution in use for DataShuttle-12, 16 bit resolution for
DataShuttle-16; it is approximate as resolution varies with temperature measured.
Thermocouples use the 50 mV range. For inputs below -5 mV (below approximately -100 degrees C),
use the +/-25 mV range.
Cold Junction Compensation Error – For the best resolution while using the DataShuttle-TCs, use the
50 mV range above -5 mV. Cold Junction Compensation Error (degrees C) at terminal temperature of:
Cold Junction Compensation Error
Type 25 o C 15 o & 35 o C 5 o & 45 o C
J 0 < 0.25 < 0.6
K 0 < 0.3 < 0.7
E 0 < 0.3 < 0.8
T 0 < 0.4 < 1.2
S 0 < 0.6 < 1.3
R 0 < 0.4 < 1.6
B 0 < 1.0 < 2.0
G 0 < 0.7 < 1.7
C 0 < 0.5 < 1.2
D 0 < 0.6 < 1.8
N 0 < 0.6 < 1.2
Cold junction compensation error is in reference to the temperature of the terminals. For types B and G the
above error applies for measured temperatures above 200 degrees C only. The cold junction sensor can
be re-calibrated at any temperature from 0°C to 50°C to improve the accuracy if it will not be used at 25°C.
Cold Junction Temperature Differential
For the DataShuttle-TC only, the temperature gradient in the air adjacent to the cold junction plate
is attenuated 15 times when AWG #22 gage or smaller thermocouple wire is used. The wires are bundled
together for at least one foot from the cold junction terminals. The error is usually less than 0.1 degree C.
For the DataShuttle-GPs there is no isothermal plate. The cold junction compensation error consists of the
above table plus the difference between the terminal temperature and the cold junction sensor.
This difference can be several degrees. The above table applies only after user calibration of the cold
junction.
DataShuttle-16 RTD Accuracy
Set Resistor
Ω
RTD
Ω
Range
°C
Resolution
°C
Accuracy
°C
10 k 50 -200 to 115 0.005 0.8
20 k 50 -200 to 525 0.01 0.9
20 k 100 -200 to 115 0.005 0.8
50 k 50 -200 to >850 0.03 1.4
50 k 100 -200 to 750 0.01 1.0
50 k 200 -200 to 115 0.005 0.8
100 k 100 -200 to >850 0.03 1.4
100 k 200 -200 to 750 0.01 1.0
100 k 500 -200 to 115 0.005 0.8
200 k 200 -200 to >850 0.03 1.4
200 k 500 -200 to 525 0.01 0.9
200 k 1000 -200 to 115 0.005 0.8
500 k 500 -200 to >850 0.03 1.4
500 k 1000 -200 to 750 0.01 1.0
1000 k 1000 -200 to >850 0.03 1.4