Section 7. Installation
350
Resistance() Four-Wire Full-Bridge Bridge-Resistance (RB) Values
RS
–40
RS
0
RS
10
RS
60
°C
–40
0
10
60
RB
2551036
2554990
2555969
2560810
Procedure
1. Build circuit
1
:
a. Use
FIGURE: PT100 Resistance() Four-Wire Full-Bridge Schematic
(p. 349)
as a template.
b. Choose a 1%, 10 ppm/°C, 5000000 Ω (5 kΩ) resistors for R1 and R4
c. Balance the bridge.
i. Find the midpoint of the temperature range. The range of –40 to 60
°C is selected for this procedure, so the midpoint is 10 °C.
ii. Select a 1%, 10 ppm/°C resistor for R2 with a resistance that is
approximately equal to the resistance of the PRT at 10 °C. See
Procedure Information (PT100 Resistance() Full Bridge)
(p. 349).
Since a
103.9 Ω resistor is hard to find, use a 100 Ω resistor. It is close enough.
2. Wire circuit to datalogger:
Use
FIGURE: PT100 Resistance() Four-Wire Full-Bridge Schematic
(p. 349)
as
the wiring diagram. Wire the current return wire to the ground terminal
associated with the terminal supplying the current.
3. Calculate excitation current:
Use the following equation to calculate the best excitation current (IX) for the
measurement range –40 to 60 °C. The equation reduces the absolute result
by 1% to allow for resistor inaccuracy:
IX
max
= (VS
max
/ RB
min
) • 0.99
where,
VS
max
= 200 mV (maximum voltage in the
±
200
input range)
RB
min
= 2551036 mΩ (PT100 bridge at
–40 °C)
2
so,
IX
max
= 0.00196 mA
Summary of Contents for CR6 Series
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Page 76: ...Section 5 Overview 76 FIGURE 20 Half Bridge Wiring Example Wind Vane Potentiometer ...
Page 80: ...Section 5 Overview 80 FIGURE 23 Pulse Input Wiring Example Anemometer ...
Page 136: ......
Page 454: ...Section 8 Operation 454 FIGURE 104 Narrow Sweep High Noise ...
Page 459: ...Section 8 Operation 459 FIGURE 106 Vibrating Wire Sensor Calibration Report ...
Page 535: ...Section 8 Operation 535 8 11 2 Data Display FIGURE 121 CR1000KD Displaying Data ...
Page 537: ...Section 8 Operation 537 FIGURE 123 CR1000KD Real Time Custom ...
Page 538: ...Section 8 Operation 538 8 11 2 3 Final Storage Data FIGURE 124 CR1000KD Final Storage Data ...
Page 539: ...Section 8 Operation 539 8 11 3 Run Stop Program FIGURE 125 CR1000KD Run Stop Program ...
Page 541: ...Section 8 Operation 541 FIGURE 127 CR1000KD File Edit ...
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Page 610: ...Section 11 Glossary 610 FIGURE 137 Relationships of Accuracy Precision and Resolution ...
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