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SCC-SG Series Strain-Gauge Modules User Guide

34

ni.com

 

Figure 26.  

Half-Bridge Shunt Calibration Configuration Using SCC-SG11 

and SCC-SG03 (One Channel) to Shunt R

4

SCC-SG11

SCC-SG03

2.5 V

+

–

R

SCAL

DIO(

X 

)

ACH(

X 

)+

V

EX

+

V

EX

–

3

4

1

2

R

3

R

4

6

5

4

3

2

1

Analog Ground

Half-Bridge
Completion

Reference

2.5 V

Содержание SCC-SG Series

Страница 1: ...t nulling circuitry for each channel and an excitation circuit Each input channel includes an instrumentation amplifier with differential inputs and a fixed gain of 100 The SCC SG11 is a shunt calibra...

Страница 2: ...26 Full Bridge Type II 27 Full Bridge Type III 28 Signal Conditioning 29 Filtering 29 Amplification 29 Excitation 29 Bridge Completion 30 Offset Nulling Adjustment 30 Nulling Range Adjustment 31 Shunt...

Страница 3: ...hunt Calibration 48 Power Requirements 49 SCC SGXX Strain Gauge Input Modules 49 Maximum Working Voltage 49 Physical 49 Environmental 50 Safety 50 Electromagnetic Compatibility 50 CE Compliance 50 SCC...

Страница 4: ...ng in your software application This document discusses all of the mechanical electrical and scaling considerations of each strain gauge configuration type supported by NI Conventions The following co...

Страница 5: ...tensions and code excerpts DAQ device Data acquisition DAQ device refers to all entry level basic and full featured E Series multifunction DAQ devices SC 2345 SC 2345 refers to both the SC 2345 connec...

Страница 6: ...yourself by using a grounding strap or by touching a grounded object Touch the antistatic envelope to a metal part of the computer chassis before removing the module from the envelope Remove the modul...

Страница 7: ...he Shunt Calibration Using the SCC SG11 section Connecting Strain Gauge Input Signals The SCC SGXX has a fixed screw terminal receptacle and a removable screw terminal block as shown in Figure 1 Note...

Страница 8: ...tivity and interface panelettes to customize the SCC system Panelettes simplify signal connection to the SCC modules and eliminate the need to rewire signals to the screw terminals when you change the...

Страница 9: ...dge configuration types However to measure the quarter bridge configuration type II you must use the SCC SG03 Refer to the SCC SG03 Half Bridge Connection section for more information The SCC SG01 mod...

Страница 10: ...s a general quarter bridge type I circuit diagram Figure 4 Quarter Bridge Type I Circuit Diagram The following symbols apply to the circuit diagram and equations R1 and R2 are half bridge completion r...

Страница 11: ...esponding reference screw terminal R X and R X 8 The dummy resistor must be equal in value to the nominal resistance of the active strain gauge element The SCC SG01 contains one 120 quarter bridge com...

Страница 12: ...uration type that requires half bridge completion The following sections describe how to connect half bridge strain gauge configuration types I and II and quarter bridge strain gauge configuration typ...

Страница 13: ...alf Bridge Type II This section provides information for the half bridge strain gauge configuration type II The half bridge type II only measures bending strain Figure 8 shows a general half bridge ty...

Страница 14: ...etion on the SCC SG03 for the quarter bridge type II to function properly Figure 4 shows a general quarter bridge type II circuit diagram Figure 9 Quarter Bridge Type II Circuit Diagram The following...

Страница 15: ...senses the output voltage of the strain gauge with respect to the internal half bridge completion reference Figure 10 shows two half bridge configurations using ACH X and ACH X 8 R4 Strain Gauge Acti...

Страница 16: ...SG04 24 module labels display the icon shown in Figure 11 These icon labels also represent the bridge configuration of the modules Note By factory default the nulling resistors are not installed in t...

Страница 17: ...Type II This section provides information for the full bridge type II strain gauge configuration The full bridge type II only measures bending strain Figure 13 shows a general full bridge type II circ...

Страница 18: ...I circuit diagram Figure 14 Full Bridge Type III Circuit Diagram The following symbols apply to the circuit diagram and equations R1 is an active element measuring compressive Poisson effect R2 is an...

Страница 19: ...d to VEX and VEX provide excitation voltage to the strain gauges The other two wires connected to ACH X and ACH X sense the output voltage of the strain gauges Figure 15 shows two full bridge configur...

Страница 20: ...here you installed an SCC 9 Click Add and select the SCC you installed If the module name does not appear in the list either the module is not allowed in that location or you do not have the current v...

Страница 21: ...SCC system using MAX automatically sets the DAQ device analog input mode to nonreferenced single ended NRSE Virtual Channels Physical Channels and Tasks After you have installed and configured your SC...

Страница 22: ...nels by pressing the Shift key while making the selections or individual channels by pressing the Ctrl key while making the selections If you are creating a channel you can select only one channel Cli...

Страница 23: ...of the two voltage dividers VCH A physical phenomena such as a change in strain applied to a specimen or a temperature shift changes the resistance of the active sensing elements in the Wheatstone bri...

Страница 24: ...in the principle direction of axial or bending strain A passive quarter bridge completion resistor dummy resistor is required in addition to half bridge completion Temperature variation in specimen d...

Страница 25: ...f Poisson s ratio Completion resistors provide half bridge completion Compensates for temperature Sensitivity at 1000 is 0 5 mVOUT VEX input Used with the SCC SG03 Dummy gauge R3 provides quarter brid...

Страница 26: ...wing characteristics Two active strain gauge elements One is mounted in the direction of bending strain on one side of the strain specimen top the other is mounted in the direction of bending strain o...

Страница 27: ...mounted in the direction of bending strain on the opposite side bottom Highly sensitive to bending strain Rejects axial strain Compensates for temperature Compensates for lead resistance Sensitivity a...

Страница 28: ...Compensates for lead resistance Sensitivity at 1000 is 1 3 mVOUT VEX input Used with the SCC SG04 24 Full Bridge Type III This section provides information for the full bridge strain gauge configurat...

Страница 29: ...alibration Using the SCC SG11 sections for more information about each type of signal conditioning Filtering Each channel on the SCC SGOX and SCC SG24 has an output lowpass filter The filter is a sing...

Страница 30: ...nt of bridge configuration circuits The nulling circuitry uses the excitation voltage as a reference and operates with quarter half and full bridge configurations Each channel has its own nulling circ...

Страница 31: ...resistors on the SCC SG0X and SCC SG24 is 30 k These nulling resistors are socketed for easy replacement Refer to the Replacing Resistors section for more information on replacing resistors To determi...

Страница 32: ...bration module label displays the icon shown in Figure 24 This icon label also represents the shunt calibration configuration using the SCC SG11 with the SCC SG0X or SCC SG24 Figure 24 SCC SG11 Icon C...

Страница 33: ...es User Guide Figure 25 Quarter Bridge Shunt Calibration Configuration Using SCC SG11 and SCC SG01 02 One Channel to Shunt R4 SCC SG11 DAQ Device ACH X SCC SG01 02 x 100 2 5 V RSCAL DIO X ACH X R X VE...

Страница 34: ...34 ni com Figure 26 Half Bridge Shunt Calibration Configuration Using SCC SG11 and SCC SG03 One Channel to Shunt R4 SCC SG11 SCC SG03 2 5 V RSCAL DIO X ACH X VEX VEX 3 4 1 2 R3 R4 6 5 4 3 2 1 Analog...

Страница 35: ...e SCC SG11 When DIO X is set to 1 on the DAQ device the shunt calibration circuits are enabled and the LED indicator on the SCC SG11 is lit When DIO X is set to 0 the circuits are disabled and the LED...

Страница 36: ...01 k VEX 2 5 VDC Offset Voltage 0 VDC then VEXPECTED 0 2491 mV Note Before completing step 2 null the system offset voltage Refer to the Offset Nulling Adjustment section for information on how to nul...

Страница 37: ...e front wide labeled side toward you 3 Place the screw terminal receptacle to the left 4 Slide the top cover to the right 5 Lift off the cover 6 Locate the completion resistor and replace it with a re...

Страница 38: ...Parts Locator Diagram Note Replacing a nulling resistor can give you a larger nulling range but makes the trimming potentiometers less sensitive when you adjust them Replacing the Shunt Resistors The...

Страница 39: ...AQmx using a strain task or global channel You also can scale the voltages manually in your application using the voltage to strain conversion equations provided in this document for each configuratio...

Страница 40: ...eighborhood of MAX to convert voltage measurements into units of strain To convert properly scaled voltage measurements to units of strain complete the following steps 1 Read the bridge configuration...

Страница 41: ...length is very short 10 ft depending on the wire gauge For example 10 ft of 24 AWG copper wire has a lead resistance of 0 25 W Rs is the shunt calibration resistor value U is the ratio of expected si...

Страница 42: ...equation To simulate the effect on strain of applying a shunt resistor across R4 use the following equation Half Bridge Type II To convert voltage readings to strain units use the following equation...

Страница 43: ...eadings to strain units use the following equation To simulate the effect on strain of applying a shunt resistor across R4 use the following equation Full Bridge Type III To convert voltage readings t...

Страница 44: ...on SCC SG01 Quarter bridge 120 SCC SG02 Quarter bridge 350 SCC SG03 Half bridge SCC SG04 Full bridge Analog Input Number of strain gauge channels 2 differential Input signal ranges 100 mV fixed gain o...

Страница 45: ...ratio CMRR 110 dB min Output range 10 VDC max Excitation Number of channels 1 Level 2 5 VDC 0 4 Current drive 42 mA2 Drift 13 mV C Strain Gauge Bridge Completions Quarter bridge One 120 1 4 W 0 1 tole...

Страница 46: ...e Overvoltage protection 42 VDC powered on and powered off Inputs protected 0 1 Transfer Characteristics Gain 100 Gain error 0 20 of reading max Offset error 50 V typ 325 V max before calibration1 Non...

Страница 47: ...10 nA max Input offset current 10 nA max Dynamic Input noise 0 1 to 10 Hz 0 4 Vrms 2 5 V pp Input noise 3 Vrms 25 V pp Stability Recommended warm up time 5 minutes Gain drift 10 ppm C max1 Offset err...

Страница 48: ...0 mW max 15 VDC 11 4 mA max 15 VDC 11 4 mA max Digital power 930 mW max 5 VDC 186 mA max Operating voltage range 15 VDC 10 15 VDC 10 5 VDC 5 SCC SG11 Shunt Calibration Module Digital I O Number of cha...

Страница 49: ...voltage refers to the signal voltage plus the common mode voltage Channel to earth 12 VDC Installation Category I Module to module 12 VDC Installation Category I Channel to channel 12 VDC Installation...

Страница 50: ...0 1 UL 3111 1 UL 61010B 01 CAN CSA C22 2 No 1010 1 Note For UL and other safety certifications refer to the product label or to ni com Electromagnetic Compatibility Emissions EN 55011 Class A at 10 m...

Страница 51: ...CC Module Bottom View Table 3 lists the signal connection corresponding to each pin ACH X and ACH X 8 are the analog input signal channels of the DAQ device AIGND is the analog input ground signal and...

Страница 52: ...e appropriate location Help Patents in your software the patents txt file on your CD or ni com patents 2002 2003 National Instruments Corp All rights reserved 323098B 01 May03 323098B 01 9 5 V 5 V 10...

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