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Campbell ST350 Instruction Manual

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ST350 Strain Transducer
2/08
C o p y r i g h t
©
2 0 0 8
C a m p b e l l
S c i e n t i f i c ,
I n c .

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Summary of Contents for Campbell ST350

  • Page 1 ST350 Strain Transducer 2/08 C o p y r i g h t © 2 0 0 8 C a m p b e l l S c i e n t i f i c , I n c .
  • Page 2 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.

  • Page 3: Table Of Contents

    8.1 CR1000 Example ................. 8-1 8.2 CR5000 Example ................. 8-2 Appendices A. Special Instructions for using ST350 ....A-1 A.1 Instructions for Using ST350 Strain Transducer Extensions on Reinforced Concrete Structures.............. A-1 A.2 Attaching the Concrete Extension to a Strain Transducer ....A-2...
  • Page 4 ST350 Table of Contents B. ST350 Accuracy Verification ........B-1 B.1 Verifying the Accuracy of ST350 Strain Transducers......B-1 B.1.1 Introduction ................B-1 B.1.2 Background................B-1 B.1.3 Factory Calibrations..............B-1 B.1.4 Temperature Effects..............B-2 B.1.5 Specimen Type and Size............B-2 B.1.6 Items for Consideration .............

  • Page 5: Introduction

    Now, most field strain gage installations can be replaced with the highly accurate ST350 Strain Transducer. These units are rugged and can be installed in any weather. Since they are pre-wired and easy to mount, ST350 Strain Transducers will drastically reduce your field installation time.
  • Page 6 Section 1. Introduction...

  • Page 7: Specifications

    Section 2. Specifications Effective gage 3.0 in (76.2 mm). Extensions available for use on R/C length: structures. Overall Size: 4.375 in x 1.25 in x 0.5 in (111 mm x 32 mm x 13 mm). Cable Length: 10 ft (3 m) standard, any length available. Material: Aluminum Full wheatstone bridge with four active 350 Ω...
  • Page 8 Section 2. Specifications...

  • Page 9: Sensor Alignment And Installation

    Installation 3.1 Alignment The BDI ST350 will only measure strain in the axis in which it is aligned with, therefore the more accurate the alignment, the more accurate the measurements will be. The easiest way to align a transducer is to mark a “grid” type pattern for both the proper foot placement and measurement axis.

  • Page 10: Installation

    30 inches long in order to be seen behind the transducer/ extension combination. It is important that this line is drawn carefully as the strains are inherently more susceptible to error due to misalignment as the gage length increases. FIGURE 3-3. ST350 Mounting Example...

  • Page 11: Adjusting Excessive Transducer Offset

    Section 3. Sensor Alignment and Installation 3.3 Adjusting Excessive Transducer Offset If it is determined that zeroing cannot be accomplished with the Wheatstone Bridge circuit, then it is possible that the transducer has either been damaged or deformed slightly. In many cases the deformation is caused by a thermal change in the gage due to weather changes, such as location of the sun.
  • Page 12 Section 3. Sensor Alignment and Installation...

  • Page 13: Wiring

    Campbell Scientific, Inc. data acquisition systems support the use of a full Wheatstone bridge sensor. The ST350 strain transducer has four active arms consisting of 350 Ω strain gages. This configuration provides approximately 3 to 3-1/2 times the output of a standard 1/4-arm foil gage installation for a given strain level.
  • Page 14 Please see informational write-up entitled “Verifying the Accuracy of ST350 Strain Transducers – Appendix B” on some of the things to look out for while running your own calibration verification.

  • Page 15: Mounting Of Sensor To Various Surfaces

    Section 5. Mounting of Sensor to Various Surfaces 5.1 General In most situations, other than reinforced concrete, the most efficient method of mounting a transducer is using the tab/glue method. This method is the least invasive and is truly a “non-destructive testing” technique. Below is an outline for implementing the glue/tab technique.

  • Page 16: Mounting Information For Different Types Of Surfaces

    Bridges, building components (columns, joists, floor systems, etc), large mechanical equipment (tower cranes, mobile cranes, cooling towers, etc.), liquid tanks, piles. 2. Methods for attaching the ST350 to steel: Tab/Glue: See above. b. C-clamps: Place transducer on specimen surface and tighten a C-clamp over each raised bolt hole.

  • Page 17: Reinforced Concrete

    1. Examples: Bridges, building components (columns, joists, floor systems, etc), foundations, piles. 2. Methods for attaching the ST350 Strain Transducer to reinforced concrete: Tab/Glue: See above. b. Tab/Glue + Threaded Stud (1/4"-20 x 3-1/4” Powers Fasteners Power-...
  • Page 18 Section 5. Mounting of Sensor to Various Surfaces Tighten the washers against the concrete by twisting the nut with an open-end wrench. It is important to set the stud before attaching the extension to prevent damaging the gage. Once secure, leave the nut on the bolt to hold the washers in place. Apply adhesive to the tab and push unit to mounting location.
  • Page 19 Section 5. Mounting of Sensor to Various Surfaces Slide the drilling jig over the stud and align it with the second hole location. Drill the second 1/4” hole and follow the previous steps for securing the second concrete anchor. Remove the washers and nut from this stud. Slide the transducer end over the stud without washers and the extension end over the one with washers.

  • Page 20: Pre-Stressed Concrete

    5.2.3 Pre-stressed Concrete 1. Examples: Bridges, building components (columns, joists, floor systems, etc), foundations, piles. 2. Methods for attaching ST350: Tab/ Glue: See above. b. Threaded Studs: 1/4"-20 x 3-1/4” Powers Fasteners Power-Stud or similar Locate the gaging point on the structure Using a concrete drill, drill 1/4”...

  • Page 21: Timber

    5.2.4 Timber 1. Examples: Bridges, building components (columns, joists, floor systems, etc), piles. 2. Methods for attached ST350: Tab/ Glue: See above. b. 2. Self-tapping Phillips-head screws: Washers are required to ensure that the head of the screw does not sink into the transducer mounting hole.
  • Page 22 Section 5. Mounting of Sensor to Various Surfaces...

  • Page 23: Calibration And Validation

    Manufacturer and a Calibration Certificate is shipped with each sensor. This certificate certifies that the sensor is traceable to NIST Standards. If this sensor is out of specification it can be sent to Campbell Scientific, Inc. for re- calibration. NOTE...
  • Page 24 Section 6. Calibration and Validation...

  • Page 25: Maintenance, Replacement Parts, And Repairs

    Section 7. Maintenance, Replacement Parts, and Repairs 7.1 Maintenance The ST350 Strain Transducer has been designed to minimize the amount of maintenance required to keep the transducers operational. Before each use it is recommended that every transducer be visually inspected for damage and powered on to ensure it is working properly.

  • Page 26: Replacement Parts

    Section 7. Maintenance, Replacement Parts, and Repairs FIGURE 7-2. Proper Connection to Data Acquisition System for Tension and Compression Debris and glue removal from foam areas between transducer body and lid: This area should be cleared of any debris or glue. The easiest way to remove any sort of obstruction from the foam area is by using a dental pick.
  • Page 27 If a transducer is damaged beyond repair, the transducer will be replaced at a discounted price. Please contact Campbell Scientific's Customer Service Department to obtain authorization for return of the unit.
  • Page 28 Section 7. Maintenance, Replacement Parts, and Repairs...

  • Page 29: Cr1000 Example

    Section 8. Datalogger Programming This section is for users who write their own datalogger programs. A datalogger program to measure this sensor can be created using Campbell Scientific’s Short Cut Program Builder Software if using LoggerNet or by using PC9000 software for the CR5000 or CR9000X. Short Cut or PC9000 are used to create the datalogger program, the sensors should be wired to the channels shown in the wiring diagram created by either program.

  • Page 30: Cr5000 Example

    Section 8. Datalogger Programming CallTable (MFGTRUSS) NextScan EndProg '***** Program End ***** 8.2 CR5000 Example 'CR5000 Example using Strain Transducer from BDI ST350 'CR5000 Program created using PC9000 (5.3) SequentialMode 'Forces program to as program is written Public TEMP Public BattVolt...
  • Page 31 Section 8. Datalogger Programming '\\\\\\\\\\\\\\\\\\\\\\\\\\\\ Bridge Blocks ////////////////////////////// 'BrFull(Dest,Reps,Range,DiffChan,ExChan,MeasPEx,ExmV,RevEx,RevDiff,SettlingTime,Integ,Mult,Offset) BRFull (BLK(),2,4,2,VX1,2,5000,False,True,4000,16670,MBLK(),OffsetVar()) 'FieldCal (0,MeasureVar,1,Multiplier,OffSet,Mode,KnownVar,Index,3) FieldCal (0,BLK(),2,MBLK(),OffsetVar(),ZeroMode,0,1,10) 'Field Cal determines zeroing coefficients CallTable CalTable CallTable MFGTRUSS Next Scan 'Loop up for the next scan EndProg 'Program ends here...
  • Page 32 Section 8. Datalogger Programming...

  • Page 33: Special Instructions For Using St350

    Concrete Structures Special gage-lengthening extensions have been designed for use with the ST350 Strain Transducers in order to measure surface strains on reinforced concrete (R/C) structures. The aluminum extensions simply increase the transducer gage length to allow an “averaged” strain value to be recorded in the presence of cracks associated with most R/C structures.

  • Page 34: Attaching The Concrete Extension To A Strain Transducer

    Appendix A. Special Instructions for using ST350 very heavy, we recommend that the gain level for the STS be set to 500. It should be noted that in most cases, the live-load strain magnitudes recorded by BDI on reinforced concrete structures have been less than 100 με.
  • Page 35 Appendix A. Special Instructions for using ST350 4. Using an extension jig as seen in FIGURE A-1, insert a tab into slot. Set the transducer over the tab into the transducer hole closest to the cable exit and loosely thread on a nut.
  • Page 36 Extension Alignment Tab in to the hole next to it (see FIGURE A-5). Screw on a 1/4-20 nut onto the tab and tighten to a torque of 50 in-lbs. Compress assembly this way before tightening FIGURE A-3. Picture Compressing ST350 for Mounting Purposes Extension Alignment Tab FIGURE A-4. Extension Alignment Tab Desired Gage Length FIGURE A-5.
  • Page 37 Appendix A. Special Instructions for using ST350 IMPORTANT: Once the extensions have been installed, the transducers are much more susceptible to damage during handling due to the large extension “lever”. To minimize possible damage, place the transducer/extension assemblies in a plastic five-gallon bucket with the extension ends down. This will allow for many assemblies to be carried at once and still be relatively protected.
  • Page 38 Appendix A. Special Instructions for using ST350 1965 57th Court North, Suite 106, Boulder, CO 80301-2826 Ph: 303.494.3230 Fax: 303-494-5027 www.bridgetest.com...

  • Page 39: Verifying The Accuracy Of St350 Strain Transducers

    Transducers B.1.1 Introduction Often, our customers like to verify the accuracy of their new ST350 Strain Transducers, something that we encourage them to do. However, there are several pitfalls that can be made while trying to check these sensors out in the laboratory.

  • Page 40: Temperature Effects

    B.1.4 Temperature Effects The ST350 Strain Transducers have been designed for recording Live Load strains only. Hence it is assumed that there will be little to no temperature change during any short time-span testing sequence. For example, most...
  • Page 41 Appendix B. ST350 Accuracy Verification Trying to measure the strain on a 2" wide strip of metal that is 1/8" thick and mounted as a cantilever beam is not a good verification test for these sensors. The primary problem with a thin bending specimen is that a large degree of curvature is required to obtain a small level of surface strain.

  • Page 42: Other Considerations

    It is recommended that the Wheatstone bridge excitation voltage stay at or below 10VDC for these sensors. Higher voltage levels can cause drifting and stability problems in the 350Ω foil gages in the transducers. The ST350 Structural Testing System uses 5VDC with very good results. A good discussion on this topic is provided in Tech Note 502 entitled "Optimizing...
  • Page 43 This again allows for a qualitative check to be completed. We are confident that if the above precautions are taken, the ST350 Strain Transducers will provide very accurate and reproducible results. If you have any questions on the above discussion or have a lab testing "pitfall"...
  • Page 44 Appendix B. ST350 Accuracy Verification...

  • Page 45: Calibration Sheets

    Appendix C. Calibration Sheets C.1 Example of Calibration Sheet — BDI Supplied FIGURE C-1. Bridge Diagnostics Calibration Sheet...

  • Page 46: Example Of Calibration Sheet - Csi Supplied

    Certificate of Calibration CUSTOMER: Company Name: Campbell Scientific, Inc Street/City/State: 815 W 1800 N, Logan, UT 84321 CSI Sales No.: Model: BDI Strain Transducer ST350 Serial Number: Instrument Calibration Condition New Strain Transducer Received Condition: Operation failure Mis-aligned (bent) Other Returned Condition: In tolerance μ...

  • Page 47: Index

    Index Adjusting Excessive Offset ........3-3 Initial Checkout Procedure – ST350 ....4-1 Alignment ST350..........3-1 Installation – ST350 ..........3-2 Alternative Mounting Techniques – ST350 ..5-1 Appendix A Attaching the Concrete Extension....A-2 Recommended Gage Length Limits....A-1 Live Loads – ST350 ..........B-2 Using ST350 on Reinforced Concrete .....A-1...
  • Page 48 Sensor ST350 Mountings........5-6 Loctite Information........... 5-1 Sensor ST350 Mountings........5-7 Maintenance Steel ..............5-2 detail............. 7-1 Attaching Methods..........5-2 Proper Function Procedure – ST350 .... 7-1 Examples ............5-2 Measurement Axis..........3-1 Installation Methods .........5-2 Mountings Pitfalls to Avoid..........5-2 Different Surfaces......... 5-2 Pre-stressed Concrete ........5-2 Reinforced Concrete........
  • Page 49 This is a blank page.
  • Page 50 Campbell Scientific Companies Campbell Scientific, Inc. (CSI) 815 West 1800 North Logan, Utah 84321 UNITED STATES www.campbellsci.com info@campbellsci.com Campbell Scientific Africa Pty. Ltd. (CSAf) PO Box 2450 Somerset West 7129 SOUTH AFRICA www.csafrica.co.za cleroux@csafrica.co.za Campbell Scientific Australia Pty. Ltd. (CSA)

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