Campbell CS547 User manual
INSTRUCTION MANUAL
CS547 Conductivity and
Temperature Probe and
A547 Interface
Revision: 9/00
Copyright (c) 1994-2000
Campbell Scientific, Inc.
Warranty and Assistance
The CS547 CONDUCTIVITY AND TEMPERATURE PROBE AND A547
INTERFACE are 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
CAMPBELL SCIENTIFIC, INC. does not accept collect calls.
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CS547 Probe and A547 Interface
Table of Contents
PDF viewers note: These page numbers refer to the printed version of this document. Use
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1. Overview......................................................................1
1.1 EC Sensor .................................................................................................1
1.2 A547 Interface ..........................................................................................1
2. Specifications .............................................................2
2.1 CS547 Probe.............................................................................................2
2.2 A547 Interface ..........................................................................................2
2.3 Temperature Sensor..................................................................................3
3. Installation...................................................................3
3.1 Site Selection ............................................................................................3
3.2 Mounting...................................................................................................3
4. Wiring ..........................................................................3
5. Programming ..............................................................4
5.1 Programming Overview............................................................................4
5.2 Measurement Programming......................................................................4
5.3 Correction of Ionization Errors in EC Measurement ................................7
5.4 Correction of Temperature Errors.............................................................8
5.5 Output Processing.....................................................................................9
6. Calibration.................................................................10
6.1 Conversion Factors .................................................................................10
6.2 Typical Ranges .......................................................................................10
6.3 Factory Calibration .................................................................................10
6.4 Field Calibration.....................................................................................10
7. Maintenance..............................................................12
8. Analysis of Errors.....................................................12
8.1 EC Measurement Error ...........................................................................12
8.2 Temperature Measurement Error............................................................14
CS547 Probe and A547 Interface Table of Contents
ii
9. Deriving a Temperature Compensation
Coefficient..............................................................15
10. Instruction 11 Details..............................................15
11. Electrically Noisy Environments............................16
12. Long Lead Lengths Temperature...........................17
13. CS547 Schematic....................................................18
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CS547 Conductivity and Temperature
Probe and A547 Interface
1. Overview
The CS547 conductivity and temperature probe, and A547 interface are designed
for measuring the electrical conductivity, dissolved solids, and temperature of
fresh water with Campbell Scientific dataloggers. They require the use of AC
excitation, so they can be used with the CR10(X), 21X, and CR7 dataloggers but
not with the BDR301 or BDR320. Use with multiplexers is possible.
Electrical conductivity (EC) of a solution is a simple physical property, but
measurements can be difficult to interpret. This manual instructs the user how to
make EC measurements with the CS547. Accuracy specifications apply to
measurements of EC in water containing KCl, Na2SO4, NaHCO3, and/or NaCl,
which are typical calibration compounds, and to EC not yet compensated for
temperature effects.
Statements made on methods of temperature compensation or estimating dissolved
solids are included to introduce common ways of refining and interpreting data, but
are not definitive. Authoritative sources to consult include the USGS Water-Supply
Paper 1473, The pH and Conductivity Handbook published by OMEGA
Engineering, physical chemistry texts, and other sources.
1.1 EC Sensor
The EC sensor consists of three stainless steel rings mounted in an epoxy tube
as shown in Figure 4-1. Resistance of water in the tube is measured by
excitation of the center electrode with positive and negative voltage.
This electrode configuration eliminates the ground looping problems associated
with sensors in electrical contact with earth ground.
Temperature is measured with a thermistor in a three wire half bridge
configuration.
1.2 A547 Interface
The interface contains the completion resistors and blocking capacitors. The
interface should be kept in a non-condensing environment that is maintained
within the temperature range of the unit.
CS547 Conductivity and Temperature Probe and A547 Interface
2
A547
Logan, Utah
MADE IN USA
A547 INTERFACE
AG
SE TEMP
EX TEMP
EX COND
DATALOGGER SENSOR
HI COND
LO COND
SHIELD
SHIELD
TEMP
COND
EX COND
EX TEMP
FIGURE 1-1. A547 Interface and CS547 Conductivity and Temperature Probe
2. Specifications
2.1 CS547 Probe
Construction The probe housing is stainless steel
Size Probe Length: 3.7 inches (94 mm)
Diameter: 0.95 inches (24.13 mm)
Maximum Cable
Length 1000 ft. The sensor must be ordered with desired length
as cable cannot be added to existing probes.
Depth Rating Maximum 1000 feet
pH Range Solution pH of less than 3.0 or greater than 9.0 may damag
e
the stainless steel housing.
Electrodes Passivated 316 SS with DC isolation capacitors.
Cell Constant Individually calibrated. The cell constant (Kc) is found on
a label near the termination of the cable.
Temp. Range of Use 0°to 50°C.
EC Range Approx. 0.005 to 7.0 mS cm-1.
Accuracy in KCl and Na2SO4, NaHCO3, and NaCl standards at
25°C:
±5% of reading 0.44 to 7.0 mS cm-1.
±10% of reading 0.005 to 0.44 mS cm-1.
2.2 A547 Interface
Size Dimensions: 2.5” x .875” x 1.750
Weight: 6 oz.
Temperature Rating -15°C to +50°C
CS547 Conductivity and Temperature Probe and A547 Interface
3
2.3 Temperature Sensor
Thermistor Betatherm 100K6A1.
Range 0°C to 50°C.
Accuracy Error ±0.4°C (See Section 8.2).
3. Installation
Rapid heating and cooling of the probe, such as leaving it
in the sun and then submersing it in a cold stream, may
cause irreparable damage.
3.1 Site Selection
The EC sensor measures the EC of water inside the stainless steel tube, so
detection of rapid changes in EC requires that the probe be flushed
continuously. This is easy to accommodate in a flowing stream by simply
orienting the sensor parallel to the direction of flow. In stilling wells and
ground wells, however, diffusion rate of ions limits the response time.
3.2 Mounting
The stainless steel housing and sensor cable are made of water impervious,
durable materials. Care should be taken, however, to mount the probe where
contact with abrasives and moving objects will be avoided. Strain on cables
can be minimized by using a split mesh strain relief sleeve on the cable, which
is recommended for cables over 100 ft. The strain relief sleeve is available
from Campbell Scientific as part number 7421.
The A547 is usually mounted in the datalogger enclosure.
4. Wiring
The excitation channel used for EC must be separate
from the one used for temperature or measurement
errors will result.
CAUTION
WARNING
CS547 Conductivity and Temperature Probe and A547 Interface
4
AG
SE TEMP
EX TEMP
DATALOGGER SENSOR
EX TEMP
TEMP
COND
EX COND
EX COND
HI COND
LO COND
SHIELD
SHIELD
FIGURE 4-1. CS547 Wiring Diagram for Example Below
5. Programming
5.1 Programming Overview
Typical datalogger programs to measure the CS547 consist of four parts:
1. Measurement of EC and temperature
2. Correction of ionization errors in EC measurements
3. Correction of temperature errors in EC measurements
4. Output processing
All example programs may require modification by the user to fit the specific
application's wiring and programming needs. All example programs in this
manual are for the CR10(X) and assume that datalogger wire connections are as
follows: the LO COND lead is connected to 1L, the HI COND to 1H, the EX
COND to EX1, the EX TEMP to EX2, and the SE TEMP to SE3.
5.2 Measurement Programming.
EC: Results from Instructions 5 or 6 (chosen automatically as part of the
autoranging feature of the following program segment) are processed with
Instruction P59 to produce the resistance across the electrodes:
Input Location Labels
Definitions for the following program:
Rs Solution resistance
Rp Resistance of leads/cable and blocking caps
Ct Solution EC with no temp. correction
C25mScm_1 EC corrected for temperature
AG
SE3
EX2
EX1
1H
1L
Clear (Shield)
Red (Temp)
Orange (Cond)
Black (Ex Cond)
Green (Ex Temp)
CS547 Conductivity and Temperature Probe and A547 Interface
5
*Table 1 Program
01: 5 Execution Interval (seconds)
;Make a preliminary measurement of resistance for autoranging.
1: Full Bridge (P6)
1: 1 Reps
2: 15 ±2500 mV Fast Range
3: 1 DIFF Channel
4: 1 Excite all reps w/Exchan 1
5: 2500 mV Excitation
6: 1 Loc [ Rs ]
7: -.001 Mult
8: 1 Offset
2: BR Transform Rf [X/(1-X)] (P59)
1: 1 Reps
2: 1 Loc [ Rs ]
3: 1 Multiplier (Rf)
;
;Test the initial measurement to make a more accurate measurement.
;
3: CASE (P93)
1: 1 Case Loc [ Rs ]
4: If Case Location < F (P83)
1: 1.8 F
2: 30 Then Do
5: AC Half Bridge (P5)
1: 1 Reps
2: 15 ±2500 mV Fast Range
3: 2 SE Channel
4: 1 Excite all reps w/Exchan 1
5: 2500 mV Excitation
6: 1 Loc [ Rs ]
7: 1.0 Mult
8: 0.0 Offset
6: BR Transform Rf[X/(1-X)] (P59)
1: 1 Reps
2: 1 Loc [ Rs ]
3: 1 Multiplier (Rf)
7: End (P95)
8: If Case Location < F (P83)
1: 9.25 F
2: 30 Then Do (cont.)
CS547 Conductivity and Temperature Probe and A547 Interface
6
9: Full Bridge (P6)
1: 1 Reps
2: 15 ±2500 mV Fast Range
3: 1 DIFF Channel
4: 1 Excite all reps w/Exchan 1
5: 2500 mV Excitation
6: 1 Loc [ Rs ]
7: -.001 Mult
8: 1 Offset
10: BR Transform Rf[X/(1-X)] (P59)
1: 1 Reps
2: 1 Loc [ Rs ]
3: 1 Multiplier (Rf)
11: End (P95)
12: If Case Location < F (P83)
1: 280 F
2: 30 Then Do
13: Full Bridge (P6)
1: 1 Reps
2: 14 ±250 mV Fast Range
3: 1 DIFF Channel
4: 1 Excite all reps w/Exchan 1
5: 2500 mV Excitation
6: 1 Loc [ Rs ]
7: -.001 Mult
8: 1 Offset
14: BR Transform Rf[X/(1-X)] (P59)
1: 1 Reps
2: 1 Loc [ Rs ]
3: 1 Multiplier (Rf)
15: End (P95)
16: End (P95)
;
;Subtract resistance errors (Rp) caused by the blocking capacitors
;(0.005Kohm) and the cable length (0.000032kohm/ft). Enter cable lead
;length in nnn below.
;
17: Z=F (P30)
1: nnn FEnter cable length in feet.
2: 00 Exponent of 10
3: 5 Z Loc [ Rp ]
18: Z=X*F (P37)
1: 5 X Loc [ Rp ]
2: .00032 F
3: 5 Z Loc [ Rp ] (cont.)
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