1. Introduction - Peekel Instruments
Contents
1. 1 4 SE 55 TIN 1 4 9 polig 9 8s male Sub D Connect cable screen pin 5 or connector case 9 IN Figure 6 Quarter bridge 3 wire straingauge connection Page 9 of 21 Peekel Instruments User manual CA2CF Version 1 0 A situation similar to the 72 bridge connection method has appeared Every 1 of difference in resistance when using 120Q straingauges gives a change in signal offset of 2 uV V This may be compensated internally by the balance circuit However the temperature influence can not be compensated for Short and thick cabling is again highly recommended 2 2 5 Displacement Transducers LVDT s or Linear Variable Differential Transformers may be configured as full or half bridges The connection method for both possibilities is shown in the next figures EX EX lt lt lt lt lt EX IN SE SE ee 5 x 1 9 polig male Sub D 9 5 Connect cable screen sk EX 5 or connector case IN IN 6 IN Figure 7 Connection of a full bridge Ivdt EX i SE SE IN 3 1 9 polig male Sub 9 15 Connect cable screen to AL EX 5 or connector case k Q IN2. EX EX EX SE SE ol IN 0 1 9 polig 6 male Sub D 5 d Connect cable screen to AL EX pin 5 or connector case 7 Q N Figure 3 Half bridge 3 wire straingauge connection EX EX SS XXX C gt OC lt gt gt gt gt SE EX SE SE if 5 m 1 IN en EN 9 polig is male Sub D 9 j 5j Connect cable screen to AL EX pin 5 or connector case SE 7 c 9 IN Figure 4 Half bridge 5 wire straingauge connection The connection of the 72 bridge completion to IN sets the amplifier for positive gain so connecting the IN signal to EX gives a positive outputsignal although in overload Half bridge connections are more critical than full bridge The leadwire resistances in the tEX lines are in series with the 2 straingauges in the Wheatstone bridge Any slight unbalance in these leadwire resistances will give rise to signal offset Every 1mQ difference in resistance on a 1200 bridge gives 2 uV V offset This may be compensated by use of the internal balance circuit However temperature influence can not be compensated Short thick cabling is highly recommended Page 8 of 21 Peekel Instruments User manual CA2CF Version 1 0 2 2 3 Quarter bridge using 2 wires Application of quarter bridges is the simplest but least accurate way of measuring The leadwires in 2 wire configurations are completely incorporated in one
3. Figure 8 Connection of a half bridge Ivdt Page 10 of 21 Peekel Instruments User manual CA2CF Version 1 0 2 3 Outputs 2 3 1 Individual analog output For each of the 2 amplifiers the output voltage 0 10 V is available on the 2 BNC connectors at the front panel of the card Page 11 of 21 Peekel Instruments User manual CA2CF Version 1 0 3 Channel Settings 3 1 General The 2 card is controlled by the processor card This can be the PB6000 card The cards are connected to each other through the backplane When the settings of a CA2CF channel must be changed this can be done by using the Active X Control The different settings shall now be explained using the property windows which are displayed by the Active X Control 3 1 1 Presentation of numbers Throughout the channel settings floating point numbers are used They are internally stored as 4 bytes and can take very small and very large values They are generally shown in the format 1 2345 or 12 345 or 123 45 where the plus sign might be replaced by the minus sign As an example values smaller than 1 00 will be shown as 123 45 m where m stands for milli or 1 1000 Also remember that 123 45mV for example is the same as 0 12345V The m can be understood as a prefix to the physical unit V in this case but can also be thought of as a suffix to the value 123 45 in this case The Active X Control always presents its floating point numbers usin
4. arm of the straingauge bridge Every 1 mQ of cabling resistance in series with a 1200 straingauge will already add 2 uV V signal offset though in practical situations it is more likely to meet several ohm s of resistance EX EX 9 N 9 polig 0 male Sub D LA Connect cable screen piel pin 5 or connector case 9 IN Figure 5 Quarter bridge 2 wire straingauge connection The balance compensation range is 65 mV V at 5 volt excitation This allows for 1 25Q total leadwire resistance in series with a 120Q straingauge A bridge voltage of 0 5 volt however gives a 10 times balance range and enables 12 5Q leadwire in series with a 120Q straingauge The temperature influence on the cable resistance cannot be compensated The temperature coefficient of copper of 0 4 C will give rise to 8 3 uV V offset change for each Q in series with a 1200 straingauge Short and thick cabling is evidently necessary 2 2 4 Quarter bridge using 3 wires Most of the problems mentioned before can be avoided by using the 3 wire connection method It adds the resistance of the Ex leadwire to the external straingauge and it adds the resistance of the wire leading to the internal 74 bridge completion to this internal 74 bridge resistance Only the difference in leadwire resistance and connector contact resistance gives signal offset EX EX tc lt
5. 10 margin to compensate cable losses when using 6 wire connections sensing This allows for e g 12 Q total cable resistance when using 120 straingauges at 5 volt excitation When the value for bridge volt is changed the amplifier will automatically perform a calibration It measures the real bridge voltage using the sense lines and corrects any deviation It is therefore necessary that the sense lines are connected on the bridge connector When sensing is not used to compensate cable losses it is still necessary to connect the sense lines on the connector itself This calibration can also be done later with the calibration command button It is even necessary when another sensor or straingauges with different resistance is connected to the amplifier 2 Notice that the output voltage of the amplifier will be disturbed during the calibration Null and full scale reference measurements are done and will be visible in the amplifier output signal The polarity parameter gives an easy method of changing the polarity of the output voltage without changing the wiring But use normal if you do not need inverted polarity Page 13 of 21 Peekel Instruments User manual CA2CF Version 1 0 Inverted polarity is the same as a negative gain When such a negative gain is entered the polarity will be on inverted mode The signal mode is usually set to normal In capacitive mode the amplifier does not measure the normal resistive signal from the strain
6. EE PX 10 2 s cota sinet un baled head eles Da QU A KR 11 2 3 1 Individual analog seed ehe Sl aces ace nt nee nce neal net ae tensed 11 3 Channel Settings ee a 12 e EE E IN e Mere 12 3 1 1 Presentation of numbers p Mn pac td Mad dual User exec duo 12 SS E GHANME or le e cats 12 3 2 1 G neral page 66 5 a 13 3 2 2 tec e ee eMe e e eR Mob et obe tla doe tus 15 o SENSOR DIE dete ro eno e Foe tele miro eph 16 3 2 4 RANGE page conne ea o aaa Boots 17 3 2 5 BALANCE ote aeo Td Roe Ted Te seed dans RS 19 2223 TA nat LETT UT 20 4 Technical Specifications u 21 Release date December 2000 J H Steeneveld Page 2 of 21 Peekel Instruments User manual CA2CF Version 1 0 1 Introduction 1 1 General The 2 is carrier frequency measuring amplifier card from Peekel Instruments B V It is designed to be used for high accuracy experimental and industrial measurements and can be used with a variety of Wheatstonebridge based sensors This card contains two individual channels and the card can be used in the SIGNALOG 6000 multi channel system A variety of resistive straingauge configurations can be connected f
7. User manual 2 PEEKEL INSTRUMENTS PEEKEL INSTRUMENTS GMBH P E E KE L INDUSTRIEWEG 161 BERGMANNSTRASSE 43 3044 AS ROTTERDAM 44809 BOCHUM INSTRUMENTS 010 415 27 22 TEL 0234 904 1603 FAX 010 437 68 26 FAX 0234 904 1605 EMAIL sales peekel nl EMAIL Peekel t online de Peekel Instruments B V User manual CA2CF Version 1 0 Contents 1 Introd ucti r sr Sura E 3 Talr Ci CIUS IE 3 1 2 The Carrier Frequency principle a 3 1 3 General design principles 4 2 Signal Connect O 5 ace 5 2 1 1 Connecting the HERR het ek tete 5 2 1 2 About Cable capacitance a a 5 2 1 3 Bridgeconnector pinout n eene rennene enna 6 2 2 SNS CONNECTIONS uA D Qd asya 7 2 2 er ta ute tee 7 2 2 2 HalPbEdgGrus eret ettet ette ett edt 8 2 2 3 Quarter bridge USING 2 wires aa rere 9 2 2 4 Quarter bridge using 3 wires eeseeseeeeeeeeenenennn 9 2 2 5 Displacement Transducers uir steer FR
8. e control R balance main 60 mV V C Balance 120 bridge up to 10 nF User manual CA2CF Version 1 0 Output Full scale voltage 10 V Protection long term shortcircuit allowed Maximum capacitive load 10 nF Maximum cable length 100 m 100 pF m Output Low pass filter Frequency 3 dB lt 2000 Hz Filter type 7 stage Butterworth 42 dB Octave Internal bridge completion 240 Q 1 2 bridge 120 or 350 1 4 bridge Page 21 of 21
9. g the number suffixes n m none k M G and T standing for pico nano micro milli none kilo Mega Giga and Tera A value of 825 0 uV V is for example the same as 0 825 mV V On the other side values larger than 999 99 will be shown for example as 1 2345 k where k stands for kilo or 1000 3 2 Channel pages The channel pages are displayed on the screen of the PC when the properties of the Active X control are displayed On the top of the property box a TAB is present for each page Clicking on the desired TAB will display that page Page 12 of 21 Peekel Instruments User manual CA2CF Version 1 0 3 2 1 General page Properties of Ca2cf Channel Control LX Bridge volt 550 Bridge Full v Signalmode v 122 240 Polarity Noma F 1 4Comp 35E Bridge load 20 0 Calibrate Output inv Presentation Annuleren Controls and Functions Bridge Volt adjustable 0 5 5 volts Signal Mode selectable Normal Capacitive Polarity selectable Normal Inverted Bridge Load adjustable 60 0 gt gt gt 3000 Ohms Output selectable Default Vout Vin Phys Bridge selectable Full Half Quarter 7 Comp fixed always 2400 1 4 Comp Selectable 1200 350Q Calibration lt execute gt Functional Description The first line bridge volt defines the excitation voltage of the transducer or straingauges Values from 0 5 5 volt are possible There is a
10. gauges but the capacitive phase shifted signal caused by cable capacitance and other parasitic causes Although the amplifier is designed to distinguish between the desired measurement and error signals when this signal is large full scale or more it can affect the accuracy of the normal measurement Capacitive unbalance is mostly observed in quarter bridge configurations with several meters of cabling The Bridge Load is standard set to 120Q However a different value can be entered The value entered here must be the impedance seen from the input of the amplifier When using full bridges this is the value of one element of the bridge This value gets more important when the bridge impedance is increasing It is used to compensate the measured value with the internal impedance of the amplifier The Output setting will influence the measured value which the control will deliver to the main application When this value is set at default the setting of the processor card will be used When set to Vout the output voltages will be delivered Setting it to Vin will result in a measurement value of the input voltage Choosing Phys the calculated physical value of the measurement will be delivered The Bridge setting will activate the internal bridge complementation A selection can be made from Full Half or Quarter complementation When Full is selected no complementation is active Selecting half or quarter will activate the half bridge complementat
11. ilt in bridge completion resistors are 120 Q for 1 4 bridge completion and 2 x 240 Q for 1 2 bridge completion see page 5 The above parameters allow calculation of the signal into the strain unit m m If further calculations are to be done to obtain the stress in the material the e modulus parameters may be set Set the use e modulus line to yes and set the e modulus unit and value as appropriate for the material to be tested Page 15 of 21 Peekel Instruments User manual CA2CF Version 1 0 3 2 3 SENSOR page This menu specifies the connected sensor like load cells or lvdt s If plain straingauges are used it is easier to use the straingauge page Properties of Ca2cf Channel Control Ea Sensor Range 0 0 k Physic unit N v Sensor VV Om Meas Sensor Annuleren Controls and Functions Sensor Range adjustable 10 000 gt gt gt 10 000 with selectable suffix pico Tera Physic Unit selectable N Nm N mm Pa ppm psi t V VIV bar C g gimme G Hz inch K lbs m m m m s or m s Input V V editable 00 000 gt gt gt 10 000 with selectable suffix pico Tera Measure lt execute gt Functional Description Sensor range specifies the physical stimulus force displacement that will generate sensor v v at the amplifier input In the shown example a load cell is specified that gives 1 mV V signal when a force of 10000 Newton is applied These values ca
12. ion The negative input signal is switch off from the input connector and connected to the half bridge complementation When selecting the quarter bridge complementation a selection can be made for the third resistor between 7200 or 3500 Page 14 of 21 Peekel Instruments User manual CA2CF Version 1 0 3 2 2 STRAIN page This page is specifically intended for using with experimental straingauge measurements If you measure a complete sensor like load cell or an lvdt it is easier to use the SENSOR page Properties of Ca2cf Channel Control LX guosgeeeeeeeegoeeoen General Strain Sensor Range Balance Trip K Factor 20 Bridge factor Use E modules o E Modules 2000 E modules unit meo TIGEDHSSET Annuleren Controls and Functions K Factor aqjustable Bridge Fact adjustable Use E Modul selectable No Yes E Modulus aqjustable 1 0000 10 000 and selectable gt gt gt Tera E Mod unit Fixed N mm Functional Description The k factor can be read from the datasheet of the manufacturer of the straingauges The bridge factor is basically equal to the number of active straingauges in the bridge If applicable it can also be used for the correction of Poisson effects in straingauge configurations When using half and quarterbridge configurations be sure to connect the internal bridge completion resistors through the bridge connector These bu
13. ith the internal on board and 4 bridge R complementary resistors These are 240 Q for 1 2 bridge and 120 Q ize or 350 Q for the 1 4 bridge d The precise value for a half bridge completion is not important as long as these resistors are stable and in balance The value of a quarter z bridge completion resistor however should fairly accurately match the external straingauge otherwise a too large unbalance offset will be the result All drawings show lines connecting the 5 with the EX lines These are the sense lines and must be connected even when not 6 but only 4 wires to the straingauge bridge are used The drawings include polarity signs within the straingauge resistors These indicate the polarity of the amplifier output signal for increasing strain and increasing resistance It is strongly recommended to use shielded cables 2 1 2 About Cable capacitance A topic inherent with the use of CF amplifiers contrary to DC amplifiers is cable capacitance The capacitance between cables to a straingauge bridge yields a parasitic impedance parallel to the arms of the Wheatstone bridge Any unbalance in capacitance may therefore lead to errors in the measured signal This becomes crucial in quarter bridge configurations where the capacitance comes directly across one arm of the bridge Example every 1 meter cabling of 100 pF meter connecting a 120 Q bridge to a 5 kHz carrier frequency amplifier gives rise to 100
14. m measured value of say 100 You then set the Trip Value at 98 If you now adjust the hysteresis at 3 the trip mechanism will perform a event generated by the Active X Control The Trip status will switch back to normal when the measured value reaches a value of 98 3 95 Unit is automatically displayed according to the measuring range set earlier Trip Control offers the facility of either not tripping at all tripping at a high level or tripping at a low level of the measured values Page 20 of 21 Peekel Instruments B V 4 Technical Specifications General Suitable for 2 3 4 5 or 6 wire connections Typical accuracy class 0 1 for bridge loads up to 1000 Q Bandwidth 3dB 2000 Hz Operating temperature 10 C 50 C Permissible cable length up to 500 m Bridge supply transformer isolated Voltage 0 5 V adjustable Voltage accuracy 0 05 Frequency 5000 Hz Frequency accuracy 1 9o Load 60 3000 Q Internal bridge completion 72 amp 74 bridge Sensing 6 wire discontinuous CPU controlled to compensate for voltage drop across cables Measuring input transformer isolated Ranges 5V excitation 100 uV 1 V V Input filter 500 Hz Maximum Common Mode Voltage 250 V Common Mode Rejection 50 Hz gt 120 dB Serial Mode Rejection gt 66 dB Capacitive input overload max 7x range permissible Special input filtering for noise reduction Balanc
15. n V V C signal offset The carrier frequency amplifier however does suppress this C signal by at least a factor 1000 This works only if the amplifier is not overloaded by the C signal The C signal therefore should not be more than 4 7 times the selected measurement range of the amplifier In the most sensitive range of 100 uV V this would allow for 10 meters of cabling Page 5 of 21 Peekel Instruments User manual CA2CF Version 1 0 The presence of such a large C signal is not recommended though In quarter bridge configurations therefore it is common practice to compensate the capacitance by a fixed capacitor built in the other arm between pins EX and 1 4 2 1 3 Bridgeconnector pinout pin 1 EX pin 2 EX excitation pin 3 input pin 4 IN input pin 5 Screen GND ground pin 6 SE sense pin 7 5 sense pin 8 not used do not connect pin 9 1 4 quarter bridge completion resistor 120 Q 350 Q The straingauge bridges and lvdt s are connected through 9 pole male DSUB connectors as seen in the above figure The abbreviations are as follows X EX Excitation to the transducers For the carrier frequency amplifier this is an AC signal of 0 5 to 5 volt at normally 5000 Hz Although the polarity signs do not have a meaning for this ac signal they are used here to indicate the relation with IN and IN XIN Differential input of the amplifier Like for the excitation
16. n often be read from the datasheet and represent mostly full load signals But the values in the sensor menu can also be obtained from in house calibration and they do not necessarily have to be full load signals If you have measured and know that your 10KN load cell produces 0 83mV V as 8 3kN is applied those values would do the job as well The parameter physic unit specifies the physical unit of the sensor A load cell could have g for gram t or N as unit and an Ivdt could have m meter as in centimeter millimeter as unit The sensor calibration can automatically be done with the measure command If this button is pressed a measurement is done and the result in V V is placed at the line input v v If you enter the value for sensor range under which physical condition the measurement was done you have obtained calibration values for this sensor Page 16 of 21 Peekel Instruments User manual CA2CF Version 1 0 3 2 4 RANGE page With this menu the amplifier can be set to a certain measurement range Properties of Ca2cf Channel Control LX Balance Trip M Range of Signal v v gt Range 40m Unit Nw Amplif out 100 Annuleren Controls and Functions Toepassen Range of selectable Amplifier Sensor Strain Range adjustable 10 0 10 0 and selectable Tera Unit provided by system Amplif V out provided by system Functional Description The
17. nce 6Q resistances in both the EX as well as the EX wire connected to a 1200 bridge give a decrease in outputsignal of 9 196 This can be compensated by using the internal sense circuit However that does not compensate the temperature influence on the leadwire resistance A temperature coefficient of 0 4 C on 12Q of copperwire connected to a 1200 bridge will still give 0 04 C change in sensitivity Short thick cabling is therefore recommended EX EX SS FEX SE SE TIN lt SIGNAL 9 polig male Sub D Q9 95 Connect cable screen to AL pin 5 or connector case IN SSS SS SSO EX Figure 1 Full bridge 4 wire straingauge connection EX EX SE XX OX XO gt OX EX SE SE N a 21 lt sIGNAL e 9 polig male Sub 9 Connect cable screen to Al EX 5 or connector case SE c IN TIN Figure 2 Full bridge 6 wire straingauge connection Page 7 of 21 Peekel Instruments User manual CA2CF Version 1 0 2 2 2 Half bridge Figure 3 amp 4 shows half bridge configured straingauges The completion resistors are internally connected to IN
18. or experimental materials testing Loadcells can be connected for industrial weighing and force measurements LVDT s Linear Variable Differential Transformers can be used for measuring linear or angular displacements and also Capacitive Transducers can be connected The processor card in the SIGNALOG 6000 system controls the settings of each amplifier on the card 1 2 The Carrier Frequency principle High accuracy measuring at the output of passive transducers is usually configured into some sort of a Wheatstone Bridge circuit which always needs some form of reference bridge supply voltage DC bridge supply is by far the most popular for resistive transducers but when it comes to the highest sensitivity DC might introduce different spurious voltages which makes the measuring unreliable In the late 50 s PEEKEL already developed the Carrier Frequency principle for these applications where an AC voltage is being used for the supply which eliminates most of these spurious and misleading signals Furthermore AC bridge supply can be also used together with capacitive and inductive transducers If dynamic signals are being measured the AC bridge supply voltage will be modulated by the measuring signal and by detecting this signal the output signal becomes available This way of measuring through modulation of a carrier frequency with detection in a later step is similar to the principle of AM radio Hence the term Carrier F
19. parameter range of determines the interpretation of the range parameter If it is set to amplifier the range represents the amplifier range in V V When it is set to sensor the range takes into account the values from the sensor menu and the range is shown with the physical unit from the sensor menu If range of is set to strain the range is calculated using the values in the strain menu and the physical unit will be m m g mm2 or N mm2 When the range of parameter is changed the unit parameter will change as well This unit can not be modified from within this menu but only in the sensor and straingauge menu s The range of parameter also determines how measurements are shown on the display when the presentation parameter in the system menu 5 after the set meas button is set to physic unit The electrical range of the amplifier when range of is set to amplifier can be set between 100uV V and 1 V V Using smaller bridge voltages than 5 volt has limitations on the smallest value that can be set as the range If the range is adjusted wrongly the settings are adjusted to the highest possible gain The value for amplif Vout determines the output voltage when full scale inputsignals are applied It is thereby possible to match to data acquisition equipment that is connected to the amplifier output Most modern systems accept the 10 10 volt signals that the CA2CF delivers by default Page 17 of 21 Peekel Instruments User manual CA2CF Ver
20. pressed a measurement is done and the result is placed on the R amp C balance lines The output of the amplifier should be near volt In the larger ranges an outputsignal of a few millivolts may be left In the 100uV V range however a maximum of 50mV may be left at the output because of the 0 5uV V resolution of the inputbalance Page 19 of 21 Peekel Instruments User manual CA2CF Version 1 0 3 2 6 Trip page This menu offers the possibility to monitor the measured value and add functions to each measurement Properties of Ca2cf Channel Control x Trip value 00 Hysteresis 0 0 Unit vw Trip control Inactive M j 1701229911 Annuleren Controls and Functions Trip Value editable 0000000 999999 Hysteresis editable 0000000 999999 provided by system Trip Control selectable unactive high signal low signal Functional Description Before setting the trip levels all other parameters have to be set Adjusting Trip Levels is practically the last adjustment before actual measuring starts The trip value can be set to any numerical value at which a switching action of the tripping function has to work This value shall be any level from within the measuring range see range menu Hysteresis can be set as the value at which the trip function goes back to normal again Normally this is a percentage of the trip value Example you wish to get a trip at 98 of the maximu
21. requency is being used The inherent use of isolation transformers assures a complete isolation between the sensor circuit and the rest of the system Page 3 of 21 Peekel Instruments User manual CA2CF Version 1 0 1 3 General design principles The following drawings only show the basic principles of the electronics as it is outside the scope of this user s manual to go in full detail The Amplifiers The drawing shows the evident advantage the two transformers fully isolating the measuring input from the rest of the system 125 uV V 1V V Demodulator Detector 9p M Input Dsub Control n1 Towpass Bridge completion Analog OUT Phase 5 KHz exc ref Page 4 of 21 Peekel Instruments User manual CA2CF Version 1 0 2 Signal Connection o At the frontpanel of the card is sub D9 connector for the input of each CA2CF channel and a coax connector for the output of each channel 4 2 1 Inputs 9 The following pages show examples of the various options of how to connect various input signals and transducers to the card Later in this document further details are given of how to actually measure these N signals B 2 1 1 Connecting the Transducers The carrier frequency amplifier is mainly used for straingauges and Ivdt s They can be connected in full half or quarter Wheatstonebridge configurations The other arms of the bridge can be AF completed w
22. sion 1 0 Note that the full scale outputvoltage as specified with amplif Vout is not the same as the maximum outputvoltage Even when 5 volt full scale is chosen a maximum of 14 volt may arise on the output during overload conditions Page 18 of 21 Peekel Instruments User manual CA2CF Version 1 0 3 2 5 BALANCE page This menu gives the offset adjustment of the sensor or straingauges Properties of Ca2cf Channel Control LX R Balance 00 C Balance 500 Bal Unit gt Balance use ves Annuleren Controls and Functions Auto Balance lt execute gt R Balance provided by system or adjustable 100 0 100 0 and selectable pico milli C Balance provided by system or adjustable 10 0 10 0 and selectable pico milli Unit provided by system Use Balance selectable Yes No Functional Description If a sensor or straingauge bridge is connected with known unbalance that unbalance value can be entered as balance in the unit which is presented by the system That value is then electronically subtracted from the inputsignal in the amplifier The use of the inputbalance can temporarily be disabled by setting use balance to no The value does not change and can be used again by setting use balance to yes again When a sensor or straingauge bridge with unknown unbalance is connected it is possible to use the auto balance function When the Balance button is
23. the polarity signs wouldn t have a meaning if they weren t used to indicate the relation with and EX Connecting EX to IN and EX to IN should give a positive but overload outputsignal tsE Sense lines for 6 wire connection of full bridges The SE and SE connections have to be connected see diagrams at the next pages in order to compensate for the voltage drop of the EXcitation voltage over the lines connected to the measuring sensors 1 4 Quarter bridge completion resistor A single external straingauge can be completed by internal resistors in the other bridge arms available 74 pins The 74 bridge completion resistor is internally connected to Ex When also the 72 pin is connected to IN a positive strain on the gauge will give a positive going output voltage from the amplifier With the settings a choice can be made between a 120 Q or a 350 Q internal compensation resistor Screen Gnd Screen ground At this pin the screen of the cable can be connected Internally in the Signalog 6000 a selection can be made to connect all the screen grounds to the earth pin of the power inlet or to connect those pins to an external ground pin Page 6 of 21 Peekel Instruments User manual CA2CF Version 1 0 2 2 Sensor Connections 2 2 1 Full bridge Figure 1 amp 2 shows the connection of a full straingauge bridge This is the most reliable configuration The leadwire resistances affect only the sensitivity of the bridge For insta
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