Campbell 108 User Guide
Model 108 Temperature Probe
Revision: 6/10
Copyright © 1985-2010
Campbell Scientific, Inc.
Warranty and Assistance
The MODEL 108 TEMPERATURE PROBE is warranted by Campbell
Scientific, Inc. to be free from defects in materials and workmanship under
normal use and service for twelve (12) months from date of shipment unless
specified otherwise. Batteries have no warranty. Campbell Scientific, Inc.'s
obligation under this warranty is limited to repairing or replacing (at Campbell
Scientific, Inc.'s option) defective products. The customer shall assume all
costs of removing, reinstalling, and shipping defective products to Campbell
Scientific, Inc. Campbell Scientific, Inc. will return such products by surface
carrier prepaid. This warranty shall not apply to any Campbell Scientific, Inc.
products which have been subjected to modification, misuse, neglect, accidents
of nature, or shipping damage. This warranty is in lieu of all other warranties,
expressed or implied, including warranties of merchantability or fitness for a
particular purpose. Campbell Scientific, Inc. is not liable for special, indirect,
incidental, or consequential damages.
Products may not be returned without prior authorization. The following
contact information is for US and International customers residing in countries
served by Campbell Scientific, Inc. directly. Affiliate companies handle
repairs for customers within their territories. Please visit
www.campbellsci.com to determine which Campbell Scientific company
serves your country.
To obtain a Returned Materials Authorization (RMA), contact Campbell
Scientific, Inc., phone (435) 753-2342. After an applications engineer
determines the nature of the problem, an RMA number will be issued. Please
write this number clearly on the outside of the shipping container. Campbell
Scientific's shipping address is:
CAMPBELL SCIENTIFIC, INC.
RMA#_____
815 West 1800 North
Logan, Utah 84321-1784
For all returns, the customer must fill out a “Declaration of Hazardous Material
and Decontamination” form and comply with the requirements specified in it.
The form is available from our website at
completed form must be either emailed to repair@campbellsci.com
435-750-9579. Campbell Scientific will not process any returns until we
receive this form. If the form is not received within three days of product
receipt or is incomplete, the product will be returned to the customer at the
customer’s expense. Campbell Scientific reserves the right to refuse service on
products that were exposed to contaminants that may cause health or safety
concerns for our employees.
www.campbellsci.com/repair
. A
or faxed to
108 Table of Contents
PDF viewers note: These page numbers refer to the printed version of this document. Use
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1. General .........................................................................1
1.1 Specifications............................................................................................1
2. Accuracy.......................................................................2
3. Installation....................................................................3
3.1 Air Temperature........................................................................................3
3.1.1 Siting...............................................................................................3
3.1.2 Assembly and Mounting.................................................................4
3.2 Soil Temperature ......................................................................................5
3.3 Water Temperature...................................................................................5
4. Wiring............................................................................5
5. Programming ...............................................................6
5.1 CRBasic....................................................................................................6
5.2 Edlog.........................................................................................................7
5.3 Example Programs....................................................................................7
5.3.1 Example Program for CR1000 Datalogger.....................................7
5.3.2 Example Program for CR10X Datalogger......................................8
5.4 Electrical Noisy Environments.................................................................8
5.5 Long Lead Lengths...................................................................................9
6. Measurement Details.................................................10
6.1 Therm108 Instruction.............................................................................10
6.2 AC Half Bridge and Polynomial Instructions.........................................10
7. Maintenance and Calibration....................................12
8. Troubleshooting ........................................................13
Figures
2-1. 108 Probe Polynomial Error Curve.........................................................3
2-2. 108 Probe Schematic...............................................................................3
3-1. 108 and 41303-5A Radiation Shield on Tripod Mast .............................4
3-2. 108 and 41303-5A Radiation Shield on a CM200 Series Crossarm .......5
i
108 Table of Contents
Tables
1-1. Recommended Lead Lengths ................................................................. 1
2-1. Thermistor Interchangeability Specification........................................... 2
2-2. Polynomial Error .................................................................................... 2
4-1. Connections to Campbell Scientific Dataloggers................................... 6
5-1. Wiring for Example Programs................................................................ 7
6-1. Polynomial Coefficients ....................................................................... 11
6-2. Actual Temperature, Sensor Resistance, and Computed Temperature. 11
ii
Model 108 Temperature Probe
1. General
The 108 temperature probe uses a thermistor to measure temperature. The
probe is designed for measuring air/soil/water temperatures. For air
temperature, a 41303-5A radiation shield is used to mount the 108 Probe and
limit solar radiation loading. The 108 temperature probe is designed to be
buried or submerged in water up to 50 feet (21 psi).
For the –L option, the probe’s cable terminates in pigtails that connect to a
Campbell Scientific datalogger or a connector that attaches to a prewired
enclosure. For the –LC option, the probe’s cable is fitted with a connector that
attaches to an ET107, ET106, or MetData1 Weather Station. Throughout this
manual, 108 will refer to both the 108-L and 108-LC unless specified
otherwise.
Lead length for the 108-L and 108-LC is specified when the sensor is ordered.
Table 1-1 gives the recommended lead length for mounting the sensor on a
tripod or tower.
TABLE 1-1. Recommended Lead Lengths
2 m Height Atop a tripod or tower via a 2 ft crossarm such as the CM202
Mast/Leg CM202 CM6 CM10 CM110 CM115 CM120 UT10 UT20 UT30
9' 11' 11' 14' 14' 19' 24' 14' 24' 37'
Note: Add two feet to the cable length if you are mounting the enclosure on the leg base of a light-weight tripod.
The 108 ships with:
(1) Resource CD
1.1 Specifications
Sensor: BetaTherm 100K6A Thermistor
Temperature
Measurement Range: -5° to +95°C
Thermistor
Survival Range: -50° to +100°C
Thermistor
Interchangeability Error: Typically <±0.2°C over 0°C to 70°C ±0.3 @ 95°C.
Steinhart-Hart
Equation Error: ≤±0.01°C (CRBasic dataloggers only)
1
Model 108 Temperature Probe
Polynomial
Linearization Error: <±0.5°C over -5°C to +90°C (Edlog dataloggers
only)
Time Constant in Air: 200 ± 10 seconds
Maximum Lead Length: 1000 ft.
NOTE
2. Accuracy
The black outer jacket of the cable is Santoprene
compound was chosen for its resistance to temperature extremes,
moisture, and UV degradation. However, this jacket will
support combustion in air. It is rated as slow burning when
tested according to U.L. 94 H.B. and will pass FMVSS302.
Local fire codes may preclude its use inside buildings.
The overall probe accuracy is a combination of the thermistor's
interchangeability specification, the precision of the b ridge resistors, and the
Steinhart-Hart equation error (CRBasic dataloggers) or the polynomial error
(Edlog dataloggers). In a "worst case" all errors add to an accuracy of ±0.3°C
over the range of -3° to 90°C and ±0.7°C over the range of -5°C to 95°C. The
major error component is the interchangeability specification of the thermistor,
tabulated in Table 2-1. For the range of 0° to 50°C the interchangeability error
is predominantly offset and can be determined with a single point calibration.
Compensation can then be done with an offset entered in the measurement
instruction. The bridge resistors are 0.1% tolerance with a 10 ppm temperature
coefficient. Polynomial errors are tabulated in Table 2-2 and plotted in Figure
2-1.
TABLE 2-1. Thermistor
Interchangeability Specification
®
rubber. This
2
Temperature (°C)
−5
0 to +50 0.20
+70 0.20
+90 0.31
TABLE 2-2. Polynomial Error
-5° to +95° <±0.5°C
-3° to +90° <±0.1°C
Temperature
Tolerance (±°C)
0.25
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