Section 7. Installation
291
FIGURE 70: PT100 Resistance() Basic-Circuit Schematic
Procedure Information
Resistance() Basic Circuit Equation
X = V / IX = RS
Procedure
1. Build circuit
1
:
a. Use FIGURE: PT100 Resistance() Basic-Circuit Schematic
(p. 291)
as a
template.
b. For Rf, choose a 1%, 10 ppm/°C, 100 Ω resistor.
2. Wire circuit to datalogger:
Use FIGURE: PT100 Resistance() Basic-Circuit Schematic
(p. 291)
as the
wiring diagram.
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
/ RS
min
) • 0.99
where,
VS
max
= 50 mV (max input voltage allowed in
±
50
input range)
RS
min
= 84270 mΩ (PT100 at
–40 °C)
1
so,
IX
max
= 0.05874 mA
Summary of Contents for CR3000 Micrologger
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Page 485: ...Section 8 Operation 485 8 11 2 Data Display FIGURE 110 Keyboard and Display Displaying Data ...
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