Fluke 9100 - Page 258

4.15-6 Section 4: Using the Model 9100: RTD Temperature Function
Final Width = 215mm
4.15.4.4 Configuration for RTD Temperature Function in the 9100
The 9100 uses 'Active Impedance' technology to output a 'Virtual Resistance'. The
method relies on the UUT having a form of measurement illustrated by Fig. 4.15.1.
The 9100 will produce a DC voltage (
V
R
) in response to a DC current (I
R
) being sourced
from the UUT. The value of the voltage is derived electronically from the value of the
I
R
multiplied by the Total Resistance Demand value (R
T
) converted from the temperature
set on the display: V
R
= I
R
x R
T
.
The effect is that of placing a resistor of value
R
T
(Virtual Resistance) between the front
panel Hi and Lo terminals of the 9100. The method is shown in Fig. 4.15.2.
Fig. 4.15.2 Model 9100 Configuration for
RTD Temperature Function
I R
Hi Lo
Model 9100
Virtual R T
Gain
Control
Total
Resistance
Demand
G
R IN
R SET
R STD
0V 0V
I R
V R
Lead-Impedance Compensation Bridge
Resistance
Calculation
Resistance-
Temperature
Conversion
and Display
Voltage
Measurement
Pseudo
Constant
Current
Source
V R
°C
Com
Sense Hi Sense Lo
I R
UUT
AA
AA
Temperature
Selection and
Conversion to
Resistance