Section 8. Operation
343
FIGURE 80: Input voltage rise and transient decay
CRBasic Measurement Settling Times
SettlingTime
Argument
Integ
Argument
Resultant
Settling Time
1
0
250
200 µs
0
_50Hz
3 ms
0
_60Hz
3 ms
integer ≥
100
integer
μs entered in
SettlingTime
argument
1
200 µs is the minimum settling time required to meet CR3000 resolution
specifications.
Settling Errors
When sensors require long lead lengths, use the following general practices to
minimize settling errors:
•
Do not use wire with PVC-insulated conductors. PVC has a high
dielectric constant, which extends input settling time.
•
Where possible, run excitation leads and signal leads in separate shields
to minimize transients.
When measurement speed is not a prime consideration, additional time can be
used to ensure ample settling time. The settling time required can be measured
with the CR3000.
•
When relatively large resistances are measured (> 1000 ohms), or
relatively long cable lengths are used (> 50 feet) with sensors requiring
current excitation, a 0.1 µf feed-forward capacitor should be placed
between the IX and IXR to prevent excessive ringing
(p. 553).
With this
capacitor present, a minimum of 3 ms is recommended for the
SettlingTime parameter in the measurement instruction. The capacitor
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 ...
Page 487: ...Section 8 Operation 487 FIGURE 112 CR1000KD Real Time Custom ...
Page 491: ...Section 8 Operation 491 FIGURE 116 Keyboard and Display File Edit ...
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Page 564: ...Section 11 Glossary 564 FIGURE 126 Relationships of Accuracy Precision and Resolution ...
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