BDI ST350 Operation Manual

ST350 - STRAIN

TRANSDUCER

Version 3.0, 0718

OPERATIONS MANUAL: ST350 STRAIN TRANSDUCER

3

Document Revision History

Version

Date

Changes

1.0

5/15/2012

Initial release document

2.0

6/7/2012

 Updated to reflect the change in hardware
 Document formatting updated

2.1

1/2/2013

Interim version-minor changes to formatting

2.2

4/2/2013

 Updated to reflect the recent CE compliance approval
 Power ratings updated

3.0

7/20/18

 Updated to include new corrosion protection
 Minor changes to specifications
 New template and styles were applied

No part of this operations manual may be reproduced, by any means, without the written consent of BDI.

The information contained within this manual is believed to be accurate and reliable. However, BDI assumes no responsibility

for errors, omissions or misinterpretations. The information herein is subject to change without notification.

Copyright © 1989 – 2018

Bridge Diagnostics, Inc. (dba BDI)

4

WARRANTY INFORMATION

BDI warrants its products to be free from defects in materials and workmanship under normal use and service for thirty-six (36)
months from date of shipment. This warranty shall be void if any products have been subjected to modification, misuse, neglect,
accidents of nature, or shipping damage. Batteries have no warranty.

All equipment manufactured by BDI is intended for use by a qualified professional only. Under this warranty BDI's obligation is
limited to repairing or replacing (at BDI's option) of defective products. In no event shall BDI be liable for punitive, exemplary,
special, indirect, incidental, or consequential damages and the customer shall assume all costs of removing, reinstalling, and
shipping of defective products. EXCEPT AS STATED HEREIN, BDI MAKES NO WARRANTIES, EXPRESSED OR IMPLIED, AND
SPECIFICALLY DISCLAIMS ANY IMPLIED WARRANTY OF FITNESS FOR A PARTICULAR PURPOSE OR MERCHANTABILITY.

Before returning any product, BDI technical support must be contacted at [phone] or by visiting BDITEST.COM/contact
and submitting a request. A technician will help determine the nature of the problem and if it cannot be resolved, authorization
will be given to return the item. A return merchandise authorization (RMA) will be sent to the customer to be filled out and
shipped back with the equipment. BDI will not accept shipment of any product without prior authorization as provided herein.

Ship all equipment to:

BDI

ATTN: TECHNICAL SUPPORT

740 S PIERCE AVE UNIT 15

LOUISVILLE CO 80027

+1.303.494.3230

Version 3.0, 0718

OPERATIONS MANUAL: ST350 STRAIN TRANSDUCER

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TABLE OF CONTENTS

1. Introduction ....................................................................................................................................................... 7

1.1 About the ST350 Strain Transducer .................................................................................................................. 7

1.2 About this manual .......................................................................................................................................... 7

2. ST350 Overview .................................................................................................................................................. 8

2.1 Technical Specifications .................................................................................................................................. 8

2.2 Options and Accessories ................................................................................................................................. 9

2.3 Applications ................................................................................................................................................ 10

3. Operation......................................................................................................................................................... 10

3.1 Theory of Operation ..................................................................................................................................... 10

3.2 Potential Strain Measurement Issues .............................................................................................................. 11

3.2.1 Temperature Variation .......................................................................................................................... 11

3.2.2 Instrumentation Cable Issues ................................................................................................................ 12

3.3 Connecting to Data Acquisition Systems .......................................................................................................... 12

3.3.1 Excitation Voltage ................................................................................................................................ 12

3.3.2 Electrical Connections ........................................................................................................................... 12

3.3.3 Applying Calibration Factors .................................................................................................................. 13

3.4 Verifying ST350 Output ................................................................................................................................ 13

3.4.1 Resistance Test ................................................................................................................................... 13

3.4.2 Resolution/Noise Test ........................................................................................................................... 14

3.4.3 Sensor Response Test .......................................................................................................................... 14

3.4.4 Field Adjusting Excessive Offsets ............................................................................................................ 15

3.5 Verifying Accuracy ....................................................................................................................................... 15

3.5.1 Factory Calibration ............................................................................................................................... 15

3.5.2 Items for Consideration for User Verification Tests .................................................................................... 15

4. Installation ....................................................................................................................................................... 17

4.1 General Installation Guide ............................................................................................................................. 17

4.1.1 Prepare Mounting Area ......................................................................................................................... 17

4.1.2 Installation.......................................................................................................................................... 18

4.2 Installation on Steel Members ........................................................................................................................ 19

4.1 Installation on Concrete Members .................................................................................................................. 23

4.1.1 Concrete Mounting Studs ...................................................................................................................... 23

4.1.2 Attaching ST350 with Extension to R/C Members ...................................................................................... 24

4.1.3 Attaching Extension to the ST350 ........................................................................................................... 25

4.2 Installation on Other Surfaces ........................................................................................................................ 29

4.2.1 Timber Members .................................................................................................................................. 29

4.2.2 Composite Materials ............................................................................................................................. 29

5. Maintenance & Recalibration ............................................................................................................................... 29

5.1 Maintenance Considerations .......................................................................................................................... 29

5.2 Recalibration ............................................................................................................................................... 29

6

LIST OF TABLES

Table 1: ST350 Specifications ................................................................................................................................... 8

Table 2: ST350 Options and Accessories .................................................................................................................... 9

Table 3: Typical Applications for ST350 strain transducers ........................................................................................... 10

Table 4: ST350 Wiring Designations & Intelliducer Pinout ............................................................................................ 12

Table 5: ST350 Extension Limits............................................................................................................................... 24

Table 6: Gage Extension Factors .............................................................................................................................. 24

Table 7: Maximum Strain Ranges ............................................................................................................................. 25

LIST OF FIGURES

Figure 1: ST350 Drawing (inches) ............................................................................................................................. 8

Figure 2: ST350 Schematic ...................................................................................................................................... 11

Figure 3: Noise levels of the ST350 on a 24-bit data acquisition system ......................................................................... 14

Figure 4: Typical Smooth Output Response and Zero Offset ......................................................................................... 14

Figure 5: Alignment Marking for ST350 Installation ..................................................................................................... 18

Figure 6: Mounting Position & Surface Preparation Marks ............................................................................................. 18

Figure 7: Typical ST350 Installation .......................................................................................................................... 19

Figure 8: Identifying Metric vs. Imperial Tabs............................................................................................................. 19

Figure 9: Mounting Tabs on the ST350 using the Tab Jig ............................................................................................. 20

Figure 10: Marking ST350 Center Mounting Location ................................................................................................... 20

Figure 11: Tab Removal Tool (TRT) .......................................................................................................................... 21

Figure 12: TRT with a Tab Inserted .......................................................................................................................... 22

Figure 13: Removing a Tab with the TRT................................................................................................................... 22

Figure 14: ST350 Concrete Drilling Jig ....................................................................................................................... 23

Figure 15: ST350 Extension Mounting Jig .................................................................................................................. 26

Figure 16: ST350 Extension Mounting Diagram .......................................................................................................... 26

Figure 17: Aligning ST350 and Extension in the Jig ..................................................................................................... 27

Figure 18: Extension Alignment Tab ......................................................................................................................... 27

Figure 19: Attaching Tab to Extension ....................................................................................................................... 27

Figure 20: ST350 With Extensions Attached to an R/C Structure ................................................................................... 28

Version 3.0, 0718

OPERATIONS MANUAL: ST350 STRAIN TRANSDUCER

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1. INTRODUCTION

1.1 ABOUT THE ST350 STRAIN TRANSDUCER

The ST350 strain transducers have been designed for recording dynamic and other induced strains on all types of structural
members and to be compatible with most data acquisition systems. While mostly used in rugged field applications, they are also
suitable for many laboratory and manufacturing scenarios. The ST350 internal circuitry consists of a full Wheatstone Bridge with
four fully-active 350Ω foil gages optimized to provide a high electrical output for a given strain magnitude. Each transducer is
individually calibrated with a highly-accurate, N.I.S.T.-traceable calibration system.

Each unit is fully sealed, designed to exceed the IP67 rating, and equipped with two pre-drilled mounting holes to keep the gage
lengths consistent for all installations. Based on the structure’s material and length of time the ST350 is to be installed, various
mounting techniques can be used including adhesives, welding, expandable anchors, and screws.

1.2 ABOUT THIS MANUAL

This is a comprehensive document that explains the functions and features of the ST350. BDI also manufactures two types of
data acquisition systems, which will be referenced throughout the manual.

1. Structural Testing System (STS): Rugged, wireless, battery powered DAQ that includes an intelligent (Intelliducer)

connector design, which makes the system extremely easy to deploy on a variety of field projects.

2. Structural Monitoring System (SMS): Modular system with 4- or 16-channel nodes that can be used in laboratories or

on permanent large scales monitoring projects.

The following highlighted message blocks will periodically appear and contain important information that the user should be
aware of.

STOP: This symbol and corresponding message represents information regarding the device that if not

followed could lead to damaging the device! Pay close attention to this message.

WARNING: This symbol and corresponding message represents vital information and is critical for the

device operation and/or the operational settings/configuration.

INFORMATION: This symbol and corresponding message represents general information and/or tips on

successfully operating/configuring the device.

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2. ST350 OVERVIEW

2.1 TECHNICAL SPECIFICATIONS

Figure 1: ST350 Drawing (inches)

Table 1: ST350 Specifications

MODEL

ST350

TYPE

350Ω

CIRCUIT

Full Wheatstone bridge with 4 active 350Ω strain gages

EXCITATION VOLTAGE

+1.0 to +10.0 Vdc

OUTPUT

mV level, ratiometric to Excitation Voltage

OFFSET

< 1.5 mV at time and temperature of calibration

POWER RATING:
MAX
TYPICAL
INTELLIDUCER1

300 mW
72 mW @ +5.0 Vdc
13 mW @ +5.0 Vdc

STRAIN RANGE

±4,000 µε (Calibrated to ±2,000 µε)

FORCE REQUIRED FOR 1,000µε

~17 lb (~76N)

TYPICAL SENSITIVITY

~500 με/mVout/Vin

ACCURACY2

< ±1%

CALIBRATION

Individually calibrated using N.I.S.T.-traceable automated system.
Calibration curve & factor provided

THERMISTOR (OPTIONAL)

3 kΩ - NTC

EFFECTIVE GAGE LENGTH

3.0 in (76.2 mm) [Gage Extensions available for R/C structures]

CABLE

Custom lead cable length made to order:
IC-02-187 [22 AWG, 2 shielded pair, drain wire, red PVC jacket]
IC-02-250 [22 AWG, 2 shielded pair, drain wire, blue PVC jacket]
IC-03-250 [24 AWG, 3 shielded pair, drain wire, black PVC jacket]

HOUSING

Machined 6061 Aluminum Alloy

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OPERATIONS MANUAL: ST350 STRAIN TRANSDUCER

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CORROSION PROTECTION

Hard Anodized Clear (MIL-A-8625 Type III)

WEATHER PROTECTION

Designed to exceed IP67
Optional 100 ft (30 m), waterproofing available

TEMPERATURE RATING3

-58° to +176 °F (-50° to +80 °C)

SIZE

4.38 in x 1.25 in x 0.50 in (111 mm x 32 mm x 12.7 mm)

WEIGHT

0.19 lb (85 g)

MOUNTING HOLES

Through holes for ¼ in (M6) bolts or anchors
Reusable mounting tabs (gluing/welding)

1

Intelliducer connector required with STS Intelliducer data acquisition nodes.

2

Accuracy defined at the calibrated ±2,000 µε range.

3

Temperature limit based on instrumentation cable operating temperatures, call BDI for wide temperature range cable options.

2.2 OPTIONS AND ACCESSORIES

The ST350 is supported by several available options and accessories depending on the application and use. See Table 2 for a
list of options and accessories that we supply.

Table 2: ST350 Options and Accessories

OPTIONS AND ACCESSORIES

Intelliducer Connector – Required for use with STS data acquisition nodes,

cable is connected and potted for a weatherproof seal

Integrated Thermistor – Temperature range of -55 °C to +220 °C, ±0.5 °C
accuracy

Reusable Mounting Tabs – ¼-20 or M6, zinc plated steel mounting tab

Tab Jig – Machined aluminum jig for safely attaching mounting tabs to the

strain transducer; Includes either 7/16 in or M10 end wrench

Gage Extension – Machined aluminum 24 in (610 mm) gage length extension
with 3.0 in (76 mm) increments