Section 7. Installation
334
Notes
•
Why use four-wire half-bridge?
Use a four-wire half-bridge when lead resistance is more than a few
thousandths of an ohm, such as occurs with long lead lengths.
•
Why use 10 kΩ series resistor?
Referring to figure
PT100 BrHalf4W() Four-Wire Half-Bridge Schematic
(p.
the 10 kΩ series resistor allows the use of a
higher-excitation voltage and
a low analog voltage input range.
•
Why use high excitation and low range?
High excitation and low range minimize the effects of signal noise.
•
Why use a bridge resistor near value of PT100?
By using a bridge resistor (Rf) that is close in value to that of the PT100
(RS), the differential measurement of V2 (voltage drop across PRT) can be
made on the same range as the differential measurement of V1 (voltage drop
across Rf). Using the same range eliminates range translation errors that can
arise from variances in the 0.01% range translation resistors internal to the
CR6.
7.7.17.4
Example: 100 Ω PRT in Three
-Wire Half Bridge with Voltage
Excitation (PT100 / BrHalf3W() )
FIGURE 72: PT100 BrHalf3W() Three-Wire Half-Bridge Schematic
Procedure Information
BrHalf3W() Three-Wire Half-Bridge Equations
X = RS / Rf
RS = Rf • X
VX = VS/(RS/(Rf + RS))
Summary of Contents for CR6 Series
Page 2: ......
Page 4: ......
Page 6: ......
Page 32: ......
Page 36: ......
Page 38: ......
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 ...
Page 546: ......
Page 552: ......
Page 610: ...Section 11 Glossary 610 FIGURE 137 Relationships of Accuracy Precision and Resolution ...
Page 612: ......
Page 648: ......
Page 650: ......
Page 688: ......
Page 689: ......