IAI 2 Impedance Analysis Interface USER MANUAL
Contents
1. 2 High frequency fixture cesses nnn 4 2 4 3 Direct connection to BNC uussensseenennnnenennenen nennen 4 3 4 4 Custom TITUS acotada 4 4 5 COMPeNSAON An ae 5 1 5 1 Short circuit compensation uusssenseeenenennenenn nennen 5 2 5 2 Open circuit compensation esses 5 3 5 3 Reference load compensation ssssssssssrsrrrrrrrrrrreres 5 4 SE lecce e EE 6 1 7 SPechicatl n s aa 7 1 Impedance analysis interface user manual APPENDI CES Appendix A Accessories Appendix B Contact details vi Impedance analysis interface user manual 1 Impedance analysis an overview Real components are never ideal resistors capacitors or inductors because of unwanted parasitic effects arising from their construction It is useful to model a real component as an appropriate combination of ideal resistance capacitance and inductance For example a real inductor at a frequency below its resonant frequency may be modelled as a pure inductor with a series resistance a real resistor may be modelled either as a pure resistor with a series inductance or by a pure resistor with a parallel capacitance a capacitor is most commonly modelled as a pure capacitor with a series resistance ESR The parameters of real components vary with the conditions of frequency and voltage current under which they are used In many cases components are used under conditions where the parasitic effects of the component beco2. ANAL NAL PSM 3750 00000 SEEEEEE mu 4 m gt e E m mE mmm BS si amp I AI 2 Impedance Analysis Interface USER MANUAL CALTEST Instruments eTil ela Caltest Instruments GmbH Tel 49 0 7842 99722 00 Fax 49 0 7842 99722 29 www caltest de Kohlmattstrasse 7 D 77876 KAPPELRODECK info caltest de Impedance analysis interface user manual IMPORTANT SAFETY INSTRUCTI ONS This equipment is designed to comply with BSEN 61010 1 Safety requirements for electrical equipment for measurement control and laboratory use observe the following precautions e Ensure that the supply voltage agrees with the rating of the instrument printed on the back panel before connecting the mains cord to the supply e his appliance must be earthed Ensure that the instrument is powered from a properly grounded supply e High voltages can be generated if current flow to inductive components is interrupted Turn off the output before connecting or disconnecting any component e Keep the ventilation holes on the underneath and sides free from obstruction e Do not operate or store under conditions where condensation may occur or where conducting debris may enter the case e There are no user serviceable parts inside the instrument do not attempt to open the instrument refer service to the manufacturer or his appointed agent Note Newtons4th Ltd shall not be liable for any consequential damages l
3. interface user manual 3 1 Shunt selection The different shunts built into the IAI2 allow the test conditions to be modified to optimise the measurement accuracy In general a higher value shunt increases the magnitude of the current signal and decreases the magnitude of the voltage signal conversely a lower value shunt decreases the magnitude of the current signal and increases the magnitude of the voltage signal Optimum accuracy is when the voltage and current signals are approximately equal the impedance of the shunt is approximately the same as the impedance of the DUT but good results can be obtained with impedances within a factor of 100 of the shunt value The accuracy also depends on the frequency of operation For example considering the normal shunt used with the PSM3750 NumetriQ with the high frequency fixture fitted directly to the rear of the IAI2 the accuracy is tabulated below normal shunt accuracy table accuracy impedance range frequency range 0 196 56 to 5000 10Hz to 100kHz 196 56 to 5000 1Hz to 1MHz 500mQ9 to 5kQ 10Hz to 100kHz 1096 50 to 5000 100uHz to 25MHz 500mQ to 5kQ 1Hz to 1MHz 50mQ to 50kQ 10Hz to 100kHz 20 5Q to 5002 10uHz to 50MHz 500m2 to 5kQ22 100uHz to 5MHz 50mQ to 50kQ 10Hz to 100kHz 3 3 Impedance analysis interface user manual It is necessary to take great care in order to achieve the best accuracy of measurement The leads of the component mus
4. product or software In the event of any problem with the instrument outside of the guarantee period Newtons4th Ltd offers a full repair and re calibration service contact your local representative It is recommended that the IAI2 be re calibrated annually along with the measurement instrument that it is used with Impedance analysis interface user manual ABOUT THI S MANUAL The Impedance Analysis Interface from Newtons4th Ltd IAI2 is a precision interface for use with the phase sensitive multimeter range of test instruments PSM3750 NumetriQ for impedance analysis applications This manual is concerned specifically with the IAI2 and its use to measure impedance a working knowledge is assumed of the PSM instrument that it is used with Detailed description of the PSM3750 NumetriQ may be found in the appropriate user manual Revision 1 00 This manual is copyright 2013 Newtons4th Ltd and all rights are reserved No part may be copied or reproduced in any form without prior written consent 16 April 2013 Impedance analysis interface user manual CONTENTS 1 Impedance analysis an overview 1 1 2 Getting Stare A TTL 2 1 2 1 UNPACKING ott 2 1 3 Usmo the Alan ee a Dua edo ote 3 1 3 1 SUE ler p 3 3 3 2 Selecting test conditions occocccccccconncconnnconnnnnn canoas 3 6 4 Connecting to the DUT eese 4 1 4 1 KelvImdeads xut acaba aate eerie de PP E PARDO 4 1 4
5. NC connection kit consists of Dual BNC adaptor BNC lead BNC splitter lead Part numbers 500 067 BNC connection adaptor A 3 Impedance analysis interface user manual Calibration kit The IAI2 is calibrated with the instrument that it is used with by means of a series of calibration fixtures Open circuit short and circuit and reference load calibration is performed for each shunt and the values stored in the non volatile FLASH memory of the instrument The calibration kit includes all the necessary fixtures four BNC coupling adaptors to fit them to the front of the IAI2 and a disc with the script file to run under CommVIEW Part numbers 500 072 IAI2 calibration kit A 4 Appendix B Contact details Please direct all queries or comments regarding the NumetriQ instrument or manual to Newtons4th Ltd 30 Loughborough Rd Mountsorrel LOUGHBOROUGH LE12 7AT United Kingdom Tel 0116 230 1066 international 44 116 230 1066 Fax 0116 230 1061 international 44 116 230 1061 E mail address sales newtons4th com office newtons4th com web site www newtons4th com At Newtons4th Ltd we have a policy of continuous product improvement and are always keen to hear comments whether favourable or unfavourable from users of our products
6. cedure please contact customer services at Newtons4th Ltd or your local authorised representative contact addresses and telephone numbers are given in the appendix at the back of this manual 2 3 Impedance analysis interface user manual 3 Using the IAI2 The device under test DUT is measured by the IAI2 in a configuration where the component is ground referenced This allows the IAl2 to be used to measure the impedance of devices even when one terminal is connected to earth The IAI2 has 4 selectable shunts to sense the current through the device under test shunt value comments LOW 50 also has 1A pk buffer NORMAL 500 HI GH 5kQ VERY HIGH 500k not recommended above 1kHz 3 1 Impedance analysis interface user manual When the shunt is selected on the instrument via the AUX menu the resistance value is automatically entered as the external shunt for channel 2 The shunt may be selected manually or the PSM3750 can be configured to select it automatically Not shown on the diagram for clarity is the 50 terminator on the OUT input connecting to the output of the PSM instrument and the 50 balancing resistors on CH1 and CH2 outputs connecting to the inputs of the PSM For high precision measurement under some conditions it may be necessary to compensate for parasitics within the test connections see the later chapter on compensation 3 2 Impedance analysis
7. d with self resetting fuses Local smoothing capacitors and possibly voltage regulators are advisable on the custom fixture The AUX connector is a 3 5mm stereo jack socket with the following pinout barrel OV middle 12V tip 12V 4 4 Impedance analysis interface user manual 5 Compensation Any cables or fixtures used to interface the device under test to the IAI2 will introduce measurement errors because of the stray impedances At low frequencies the stray effects can usually be ignored except when measuring at the extremes of the impedance range or when exceptionally high accuracy is needed At higher frequencies it is almost always necessary to compensate for the stray effects unless using the HF component fixture clipped to the front of the IAI 2 There are 3 forms of compensation 1 Short circuit for measuring low impedance 2 Open circuit for measuring high impedances 3 Reference load compensation for highest accuracy It is usually only necessary to perform one of the three forms of compensation but any two or all three can be performed For best results if more than one is to be performed they should be performed in the sequence given above In the following descriptions the impedances are shown in bold type eg Zx to indicate that they are complex values with in phase and quadrature components 5 1 Impedance analysis interface user manual 5 1 Short circuit compensation Short circuit compensa
8. e 0 196 5002 to 50kQ 10Hz to 100kHz 196 5002 to 50kQ 1Hz to 1MHz 50 to 500kQ 10Hz to 100kHz 1096 5002 to 50kQ 100uHz to 15MHz 50 to 500k2 1Hz to 1MHz 5Q to 5MQ 10Hz to 100kHz 20 5002 to 50k 10uHz to 50MHz 50 to 500k22 100uHz to 5MHz 5Q to 5MQ 1Hz to 500kHz 7 2 Impedance analysis interface user manual low shunt accuracy table accuracy impedance range frequency range 0 1 500m2 to 500 10Hz to 100kHz 196 500m2Q to 500 1Hz to 1MHz 50m to 5000 10Hz to 100kHz 1096 500m2Q to 500 100uHz to 10MHz 50m9 to 5000 1Hz to 1MHz 10mQ to 5kQ 10Hz to 100kHz very high shunt accuracy table accuracy impedance range frequency range 0 1 50kQ to 5MQ 10Hz to 1kHz 1 50kQ to 5MQ 1Hz to 1kHz 5kQ to 50MQ 10Hz to 1kHz 10 5Ok to 5MQ 100uHz to 1kHz 5kQ to 50MQ 1Hz to 1kHz 50022 to 100MQ 10Hz to 1kHz 7 3 Impedance analysis interface user manual Appendix A Accessories ACCESSORIES Impedance analysis interface user manual High frequency component fixture The high frequency component fixture clips onto the front of the IAI2 with four BNC coupling adaptors supplied for easy testing of components Part numbers 500 066 HF impedance fixture A 2 Impedance analysis interface user manual BNC connection adaptor The IAl2 can be used to directly measure the impedance of inputs and outputs of other equipment even if the BNC connector is grounded The B
9. he impedance measured by the IAl2 with the DUT connected Zx Zm Zr Zl Note Newtons4th have produced an application note detailing the process of open short and reference load compensation Please contact us and we will provide you with the document 5 4 Impedance analysis interface user manual 6 Calibration For optimum accuracy the IAl2 should be re calibrated annually with the instrument that it is used with The calibration values are stored in the instrument so the IAI2 and PSM instrument should be kept together as a pair The calibration process is similar to compensation except that it is performed over a series of frequencies The reference components used for the calibration are resistors of the same value as the internal current sense shunts The calibration procedure is controlled by a script file running under CommVI EW which instructs the operator to fit the appropriate fixture then sends the necessary commands to the instrument The calibration fixture set comprises 4 BNC to BNC couplers lor more short circuit fixtures lor more open circuit fixtures 4 reference fixtures 1 script file to run under CommVI EW The calibration process stores the measured value for Zs Yo and ZI for each frequency point and Zr Then if Zm is the impedance measured by the IAI2 Zx Zr 1 ZI Zs Yo Zm Zs 1 Zm Zs Yo Zl Zs Interpolation is used to determine the constants for frequencies bet
10. lly select test conditions or they can be entered manually DC offsets can also be added to the test voltage where needed for example testing electrolytic capacitors which need a bias voltage In this case it may be best to set the PSM instrument to AC coupling which will increase the measured accuracy in cases where the AC signal is small relative to the DC level 3 7 Impedance analysis interface user manual 4 Connecting to the DUT 4 1 Kelvin leads The IAI2 is supplied with a pair of Kelvin leads for low frequency use 5MHz which make simple connections to a discrete component The red lead should be connected to the BNC connectors marked SIGNAL and SENSE on the front of the IAI2 the black lead should be connected to the BNC connectors marked SIGNAL and SENSE The Kelvin clips can then be clipped onto the body of the component as close as possible to the component For accurate measurements it is essential that the component leads are clean For repeatability of measurements it is important to connect the Kelvin clips in the same physical arrangement when testing different components signal sense 4 1 Impedance analysis interface user manual 4 2 High frequency fixture For testing components over all frequencies there is a dedicated test fixture available as an accessory from Newtons4th Ltd This can clip directly onto the front of the IAI2 by means of four BNC to BNC couplers supplied with it
11. me critical and must be measured reliably over a wide range of operating conditions The impedance is analysed by measurement of the complex impedance Z under controlled conditions of frequency and voltage or current Z V I where V is the voltage across the component I is the current through the component Z V and I are complex values which may be represented as magnitude and phase or by in phase and quadrature components The LCR measurement is performed by the PSM instrument using a discrete Fourier transform DFT 1 1 Impedance analysis interface user manual at the frequency of operation This gives the complex impedance directly in the form of an in phase component and a quadrature component Having measured the complex impedance Zm in the form of in phase Zr and quadrature components Zq the series and parallel models can then be computed Using traditional complex mathematical notation where j is the operator v 1 Zm Zr j Zq For the series inductance model Zq 0 Z Rs jwLls where w 2 1 frequency and Rs Zr Ls Zq W For the parallel capacitance model Zq 0 1 Z 1 Rp j Cp and Rp Zr Zq Zr Cp Zq Zr Zq It is important to characterise the component over all the frequencies that are relevant for a given applications For this reason the IAI2 can be used with the phase sensitive 1 2 Impedance analysis interface user manual multimeters from New
12. n the PSM instrument The actual voltage across the DUT depends on the impedance of the component at the test frequency and the impedance of the selected shunt If the generator output is set as a peak voltage Vpk then because of the 50 impedances the rms voltage across the series combination of shunt and DUT may be approximated as Vpk 2v2 with a series resistance of 250 Then the voltage seen by the DUT Vdut will be approximately given by Vdut Vpk 2v2 x Zdut Zdut Rshunt 25 where Zdut impedance of the DUT Rshunt resistance of the shunt The PSM instrument clearly displays the measured voltage across the DUT and the measured current through it To fix the test voltage at a specified level enable ac trim on CH1 using the TRIM menu on the instrument and set the desired rms level for Vdut The instrument will then adjust the generator output level until the measured voltage across the component is as specified Note that the low shunt also has a high speed buffer so the 25Q term does not appear and the equation becomes Vdut Vpk 2v2 x Zdut Zdut 5 The maximum rms current Imax in this case into a short circuit becomes Imax 10 2V2 5 0 7A rms 3 6 Impedance analysis interface user manual The optimum test conditions to use depend on the component or DUT and the application as many components change their characteristics with frequency and test voltage The PSM instrument can automatica
13. nnector to be tested Connect the dual BNC adaptor to the BNC terminal which is to be measured Connect the BNC lead from one end of the adaptor to the SIGNAL terminal of the IAI2 Connect the single BNC end of the BNC splitter lead to the other end of the adaptor connect the BNC with the red boot to the SENSE terminal of the IAl connect the BNC with the black boot to the SENSE terminal The SIGNAL terminal is not used in this configuration signal sense AI 2 4 3 Impedance analysis interface user manual 4 4 Custom fixtures For dedicated test facilities the IAl2 can be used with custom made fixtures The test voltage is provided at the SIGNAL terminal and the selected internal current sense circuitry measures the current that is drawn from this terminal The voltage across the DUT should be presented to the high impedance SENSE and SENSE terminals The SIGNAL terminal is not used in this configuration For remote operation at a distance from the IAI2 the fixture could have active buffers to drive the SENSE and SENSE cables to isolate the effects of the cabling from the DUT Use high impedance amplifiers eg JFET input types in x2 mode with the characteristic resistance for the cable being used usually 500 and terminate the cables at the IAI2 with the same value The AUX connector on the IAl2 provides 12V at up to 50mA per rail for powering active fixtures The outputs are current limite
14. osses costs or expenses arising from the use or misuse of this product however caused Impedance analysis interface user manual DECLARATI ON OF CONFORMITY Manufacturer Newtons4th Ltd Address 30 Loughborough Rd Mountsorrel Loughborough Leics LE12 7AT We declare that the product Description Impedance analysis interface Product name IAl2 Model Conforms to the requirements of Council Directives 2004 108 EC relating to electromagnetic compatibility EN 61326 2006 2006 95 EC relating to safety of laboratory equipment EN 61010 1 2010 April 2013 Eur Ing Allan Winsor BSc CEng MIEE Director Newtons4th Ltd Impedance analysis interface user manual WARRANTY This product is guaranteed to be free from defects in materials and workmanship for a period of 36 months from the date of purchase In the unlikely event of any problem within this guarantee period first contact Newtons4th Ltd or your local representative to give a description of the problem Please have as much relevant information to hand as possible If the problem cannot be resolved directly then you will be given an RMA number and asked to return the unit The unit will be repaired or replaced at the sole discretion of Newtons4th Ltd This guarantee is limited to the cost of the IAl2 itself and does not extend to any consequential damage or losses whatsoever including but not limited to any loss of earnings arising from a failure of the
15. t be scrupulously clean and for repeatability the component must be connected in exactly the same position Slight variations in connection can result in significantly different measured values especially at high frequencies In general the very high shunt should only be used for high impedance measurements gt 1MQ at low frequencies 1kHz The low shunt is used with higher current testing of low impedances as it includes a current boosting amplifier that can deliver up to 0 5A rms Warning high voltages can be generated when the current flowing through an inductive component is interrupted So turn the output off before disconnecting an inductive or unknown component The normal and high shunts are general purpose and between them cover a very wide impedance range shunt frequency ranges shunt impedance range frequency range low lt 500 lt 10MHz normal 50mQ to 50k22 all high 5 to 5MQ all very high gt 1MQ lt 1kHz Of course this table is only a guide and each shunt can be used beyond the limits quoted 3 4 Impedance analysis interface user manual If automatic shunt selection is configured on the instrument then the appropriate shunt will be automatically selected according to the test conditions and the measured impedance 3 5 Impedance analysis interface user manual 3 2 Selecting test conditions The frequency and voltage of the generator are selected o
16. te test component eg a 100nF capacitor Verify that the voltage ratings on the rear panels of the IAI2 and the instrument are appropriate for the supply and then connect the mains cords to the inlets on the rear panels and the supply outlet Switch on the IAl2 and the instrument All four led s on the front of the IAI2 should illuminate The display on the instrument should illuminate with the model name and the firmware version for a few seconds while it performs some initial tests It then normally defaults to the RMS voltmeter display unless some other mode has been stored into the start up program PROG 1 Press the AUX key on the instrument and select fixture IAL and shunt normal Only the normal LED should now be illuminated on the front panel of the IAI2 If the instrument displays the message FIXTURE NOT RESPONDING Then check that the extension port cable has not been damaged and has been correctly fitted between the instrument and the IAI2 If the message does not appear but all 4 led s remain illuminated and flashing then check that the IAI2 is correctly connected to the supply switched on at the rear and that the fuse is intact Press the OUT key on the instrument and turn on the output 2 2 Impedance analysis interface user manual Press the LCR key to select the impedance analyser function and check that the test component is measured correctly In the event of any problem with this pro
17. tion compensates for the stray impedance in series with the impedance to be measured IAI2 Then if Zm is the impedance measured by the IAI Zm Zs Zx To compensate for Zs a measurement is made with the DUT shorted out but with all the cables in the same place This measures Zs directly and is stored as Zs Then the DUT is replaced without disturbing any wiring and the true Zx can be derived from Zm and Zs Zx Zm ZS 5 2 Impedance analysis interface user manual 5 2 Open circuit compensation Open circuit compensation compensates for the stray impedance in parallel with the impedance to be measured IAI 2 Then if Zm is the impedance measured by the IAI 1 Zm 1 Zo 1 Zx To compensate for Zo a measurement is made with the DUT removed but with all the cables in the same place This measures Zo directly and is stored as Yo 1 Zo Then the DUT is replaced without disturbing any wiring and the true Zx can be derived from Zm and Yo 1 Zx 1 Zm Yo Or Zx Zm 1 Yo Zm 5 3 Impedance analysis interface user manual 5 3 Reference load compensation Reference load compensation compensates for complex effects within the cabling and fixtures by measuring a known reference component The value of the reference component and its phase are entered and the measured value stored IAI 2 Then if Zl is the impedance measured by the IAI2 with the known reference impedance Zr connected and Zm is t
18. to minimise effects due to cabling Connection is made to the component by four gold plated contact areas in a four wire Kelvin arrangement SIGNAL and SIGNAL appear on the lower pair of contacts SENSE and SENSE are picked up from the upper pair of contacts The lower pair of contacts are secured to the connectors attached to the IAl2 and does not move the upper pair of contacts can be lifted by light finger pressure The contacts are pressed closed by springs To insert a component push up the upper contact plate so that the legs of the component can be inserted If necessary push up the upper contact plate on one side first and then the other side so that the component can be pushed home For high frequency work it is essential for the component to be inserted as far as possible The HF fixture does not have to be clipped to the front of the IAI2 but can be used with some short BNC leads instead of the BNC couplers 4 2 Impedance analysis interface user manual 4 3 Direct connection to BNC Because the DUT is ground referenced by the IAI2 SIGNAL is connected to earth the IAl2 can be used to directly measure the input and output impedances of equipment which is earthed eg Oscilloscope inputs The easiest way to make the connections is to use the BNC connection kit available as an accessory consisting of Dual BNC adaptor BNC lead BNC splitter lead Ensure that there are no harmful voltages present on the BNC co
19. tons4th Ltd to sweep across a frequency range 1 3 Impedance analysis interface user manual 2 Getting started The IAI2 is supplied with appropriate leads and accessories for use with the PSM3750 NumetriQ phase sensitive multimeters from Newtons4th Ltd The IAI2 should be calibrated with the unit that it will be used with see the later chapter on calibration 2 4 Unpacking Inside the carton there should be the following items one IAI unit one appropriate mains lead three short BNC cables one short ribbon cable a pair of Kelvin leads for low frequency use this manual There may also be a number of optional accessories if these have been ordered with the unit Having verified that the entire above list of contents is present it would be wise to verify that your IAl2 operates correctly and has not been damaged in transit Site the IAI2 under the instrument that it will be used with Connect the 3 short BNC cables from the BNC connectors on the rear of the IAI2 OUT CHI and CH2 to the corresponding isolated BNC connectors on the PSM above it Connect the ribbon cable from the extension port on the back of the IAl2 to the extension port on the rear of the PSM Connect the red Kelvin lead to the signal and sense BNC connectors on the front of the IAI2 and connect the 2 1 Impedance analysis interface user manual black Kelvin lead to the sense and signal BNC connectors Connect the Kelvin clips across an appropria
20. ween calibration points 6 1 Impedance analysis interface user manual 7 Specification Al these specifications are quoted for the system consisting of IAI2 with HF fixture and PSM3750 NumetriQ unless otherwise stated System Frequency range 10uHz 50MHz Basic accuracy 0 196 Impedance range 1mQ 500M O 1pF 1000uF 10nH 10kH Excitation voltage 5Vpk max Excitation control voltage or current Configuration ground referenced DC offset voltage 5V max Parameters measured R L C Z phase QF tan 0 series or parallel circuit selectable shunts 4 buffer current low 0 5A rms max shunt IAI2 only connectors grounded BNC power requirements universal input 90 264V rms 47 63Hz 15VA max size 60H x 350W x 250D mm approx weight 2kg approx temperature range 5to35 C 7 1 Impedance analysis interface user manual For each shunt the accuracy of measurement depends on the impedance and the frequency normal shunt accuracy table accuracy impedance range frequency range 0 1 5Q to 5000 10Hz to 100kHz 196 50 to 5000 1Hz to 1MHz 500mQ to 5kQ 10Hz to 100kHz 10 5 to 5000 100uHz to 25MHz 500m9Q to 5kQ 1Hz to 1MHz 50mQ to 50k0 10Hz to 100kHz 2096 5 to 5000 10uHz to 50MHz 500m2 to 5k 100uHz to 5MHz 50mQ to 50kQ 1Hz to 500kHz high shunt accuracy table accuracy impedance range frequency rang
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