2638A
Users Manual
1-20
RTD Temperature Accuracy
Accuracy is for 4-wire 100
Ω
nominal RTD, using the slow sample rate. With 3-wire PRT/RTD add 0.015 °C if using
Channel 1, or add 0.15 °C internal resistance mismatch to the accuracy specification if using channels x01 through x20,
and add external lead wire resistance mismatch. When using medium or fast sample rate (NPLC <10), add the number
given in the table to the accuracy specification. If the environment temperature is outside the specified range, multiply the
Temperature Coefficient number by the temperature deviation and add to the accuracy specification. Linear interpolation
may be used between points in the table. Specifications do not include sensor accuracy. The practical range of
temperature measurement depends on the sensor and characterization.
Temperature
Accuracy
Medium/Fast Sample
Rate (NPLC <10)
T.C./ °C Outside
18 °C to 28 °C
-200 °C
0.016 °C
add 0.02 °C
0.0026 °C
0 °C
0.038 °C
add 0.02 °C
0.0041 °C
300 °C
0.073 °C
add 0.03 °C
0.0063 °C
600 °C
0.113 °C
add 0.03 °C
0.0089 °C
Note:
For conducted disturbances on mains input >1 V from 10 MHz to 40 MHz, add 0.2 Celsius. For disturbances >3 V,
accuracy is unspecified.
RTD Measurement Characteristics
Range
Temperature Display Resolution
Source Current
Slow
Sample Rate
Medium/Fast
Sample Rate
0
Ω
to 400
Ω
0.001 °C
0.01 °C
1 mA
400
Ω
to 4 k
Ω
0.001 °C
0.01 °C
0.1 mA
Thermistor
Temperature Range
.............................................. -200 °C to 400 °C (depending on the sensor)
Resistance Range
................................................. 0
Ω
to 1 M
Ω
Sample Rate
Slow .................................................................... 10 PLC
Medium ............................................................... 2 PLC
Fast ..................................................................... 1 PLC
Thermistor Temperature Accuracy
Accuracy specifications are for a 4-wire thermistor using medium or slow sample rate. With 2-wire thermistor add the
number given in the table to the accuracy specification for internal resistance. When using fast sample rate (NPLC <10),
multiply the accuracy specification by 3. If the environment temperature is outside the specified range, increase the
accuracy specification by 25 % for every 1 °C outside the specified environment temperature range. Specifications do not
include sensor accuracy. The practical range of temperature measurement depends on the sensor.
Temperature
Accuracy
2.2 k
Ω
thermistor
5 k
Ω
thermistor
10 k
Ω
thermistor
2-wire
-40 °C
0.002 °C
0.007 °C
0.007 °C
add 0.002 °C
0 °C
0.005 °C
0.004 °C
0.003 °C
add 0.004 °C
25 °C
0.013 °C
0.007 °C
0.005 °C
add 0.016 °C
50 °C
0.019 °C
0.01 °C
0.011 °C
add 0.05 °C
100 °C
0.116 °C
0.054 °C
0.026 °C
add 0.34 °C
150 °C
0.527 °C
0.239 °C
0.1 °C
add 1.7 °C
Note:
For conducted disturbances on mains input >1 V from 10 MHz to 40 MHz, add 0.2 Celsius. For disturbances >3 V,
accuracy is unspecified.
1.888.475.5235
info@Fluke-Direct.com
Fluke-Direct
.com
