Campbell Scientific 108-LC User Manual

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INSTRUCTION MANUAL
108-LC Temperature Probe
for MetData1
Revision: 4/03
Copyright (c) 1985-2003
Campbell Scientific, Inc.
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Warranty and Assistance

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 withi n their territories. Please visit www.campbe llsci.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
CAMPBELL SCIENTIFIC, INC. does not accept collect calls.
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108-LC Table of Contents
PDF viewers note: These page numbers refer to the printed version of this document. Use the Adobe Acrobat® bookmarks tab for links to specific sections.
1. General........................................................................1
1.1 Specifications............................................................................................1
2. Accuracy .....................................................................1
3. Installation and Wiri ng ...............................................4
4. Connection..................................................................4
5. Programming ..............................................................5
6. Maintenance and Calibration .....................................5
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Model 108-LC Temperature Probe for MetData1

1. General

The 108 Air/Soil/Water Temperature Probe uses thermistors to measure temperature. Custom lead lengths are available up to 1000 ft.
For air temperature measurement, a 41303 radiation shield is needed to mount the 108 Probe and limit solar radiation loading of the 108. The 108 probe is designed to be buried or submerged in water up to 100 feet.

1.1 Specifications

Temperature Measurement Range: -5° to +95°C
Thermistor Interchangeability Error: Typically <±0.2°C over 0°C to 7 0°C ±0.3 @ 95°C.
Polynomial Linearization Error: <±0.5°C over -7°C to +90°C.
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 bridge resistors, and the polynomial error. 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 -7°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.
rubber. This
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Model 108-LC Temperature Probe for MetData1
TABLE 2-1. Thermistor Interchangeability Specification
TABLE 2-3. Actual Temperature, Sensor Resistance,
Temperature Resistance Output
-10.00 612366 -9.02
10.00 207807 10.00
12.00 187803 12.04
14.00 169924 14.07
16.00 153923 16.09
18.00 139588 18.10
20.00 126729 20.09
22.00 115179 22.07
24.00 104796 24.05
26.00 95449 26.02
28.00 87026 27.99
30.00 79428 29.97
32.00 72567 31.94
34.00 66365 33.93
36.00 60752 35.93
38.00 55668 37.93
40.00 51058 39.94
42.00 46873 41.96
44.00 43071 43.98
46.00 39613 46.00
48.00 36465 48.02
50.00 33598 50.03
Temperature
Temperature (°C) Tolerance (
10 0.25
0 to +50 0.20
+70 0.20 +90 0.31
TABLE 2-2. Polynomial Error
-10 to +95 <±1.0°C
-7 to +95 <±0.5°C
-3 to +90 <±0.1°C
and Computed Temperature
°C OHMS °C
-8.00 546376 -7.36
-6.00 488178 -5.63
-4.00 436773 -3.83
-2.00 391294 -1.97
0.00 351017 -0.05
2.00 315288 1.91
4.00 283558 3.91
6.00 255337 5.93
8.00 230210 7.96
±°C)
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Model 108-LC Temperature Probe for MetData1
52.00 30983 52.03
54.00 28595 54.03
56.00 26413 56.03
58.00 24419 58.02
60.00 22593 60.01
62.00 20921 61.99
64.00 19388 63.98
66.00 17981 65.97
68.00 16689 67.96
70.00 15502 69.96
72.00 14410 71.97
74.00 13405 73.98
76.00 12479 75.99
78.00 11625 78.01
80.00 10837 80.02
82.00 10110 82.03
84.00 9438.1 84.04
86.00 8816.9 86.03
88.00 8241.9 88.00
90.00 7709.7 89.96
92.00 7216.3 91.89
94.00 6758.9 93.80
96.00 6334.5 95.67
98.00 5940.5 97.51
100.00 5574.3 99.31
FIGURE 2-1. 108 Probe Polynomial Error Curve
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Model 108-LC Temperature Probe for MetData1

3. Installation and Wiring

The 108 must be housed inside a radiation shield when used in the field for air temperature measurement. The 41303 Radiation Shield (see Figure 3-1) mounts to a CM6 or CM10 tripod. The UT018 mounting arm and UT6P Radiation Shield are used to mount the 108 to a UT30 tower.
The standard lead length of 6 feet and 9 feet allow the 108 to be mounted at a 2 meter height on the CM6/CM10 tripod or the UT30 tower respectively.

4. Connection

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FIGURE 3-1. 108 and 41303 Radiation Shield
on a CM6/CM10 Tripod Mast
The 108 cable is attached to the MetData1 connector #4 or #7. Connector #4 uses single-ended input 4L (channel 8) and connector #7 uses single-ended input 5H (channel 9). The probe is measured by a single-ended analog input channel.
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5. Programming

Model 108-LC Temperature Probe for MetData1
NOTE
01: AC Half Bridge (P5)
1: 1 Reps 2: 3 ± 25 mV Slow Range 3: 8 or 9** In Chan 4: 3 Ex Chan Option 5: 1000 mV Excitation 6: 11* Loc [ Tmp108C ] 7: 200 Mult 8: 0 Offset
02: Polynomial (P55)
1: 1 Reps 2: 11* X Loc [ Tmp108C ] 3: 11* F(X) Loc [ Tmp108C ] 4: -26.97 C0 5: 69.635 C1 6: -40.66 C2 7: 16.573 C3 8: -3.455 C4 9: .301 C5
Information in this section is not necessary when programming the MetData1 with the Short Cut Program Builder software.
Instruction 5 (AC Half Bridge) is used to measure the 108 temperature probe. Instruction 55 (polynomial) is used to find the temperature in degrees Celsius.
MetData1 Datalogger Program Example
* Proper entries will vary with input location assignments. ** Specify input channel #8 for connector #4. Specify input channel #9 for connector #7.
TABLE 5-1. Polynomial Coefficients
Coefficient Value
C0 -26.97 C1 69.635 C2 -40.66 C3 16.573 C4 -3.455 C5 0.301

6. Maintenance and Calibration

The 108 Probe requires minimal maintenance. Check monthly to make sure the radiation shield is free from debris.
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Model 108-LC Temperature Probe for MetData1
For most applications it is unnecessary to calibrate the 108 to eliminate the thermistor offset. However, for those users that are interested, the following briefly describes calibrating the 108 probes.
A single point calibration can be performed to determine the 108 temperature offset (thermistor interchangeability). This calibration will not remove the polynomial error. The value of the offset must be chosen so that the probe outputs the temperature calculated by the polynomial, not the actual calibration temperature. For example, a 108 is placed in a calibration chamber that is at 0°C and the probe outputs 0.1°C. The offset is -0.15, because at 0°C the polynomial calculates a temperature of -0.05°C (Table 5-2).
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