DX3065 Z-Meter
Contents
1. 1 2ZT 1 AT max La Ta 7 3 14 Principle of Figure of Merit Measuring 3 7 DX3065 RMT Ltd Here the dependence of Z on the temperature was ignored which is quite allowable at the temperature scale considered For instance if Z 0 0027 K and Ta 300K we have the following temperature difference AT max 10 K 3 3 Theory of Operation a TEC mounted on the heat sink 40 Heat sink means a 4 noticeable increase of heat dissipation fu itt through the TEC 4 basement It must be aj taken into account when estimating the role ofthis factor in measurement results Eguation 3 9 a Ua 1 1 b Ta 1 b Up b averaged 3 8 REV 1 00 2002 RMT Ltd DX3065 allows for heat dissipation through the warm side of TE with the corresponding term br and the voltage averaging So the estimation of the br value of the assembled TE module is possible if taking into account thermal properties of the heat sink As a rough estimation we can assume ois z 3 15 where ks thermal conductivity of the heat sink S surface of the heat sink as the TEC projecting Ls thickness of the heat sink Principle of Figure of Merit Measuring 3 9 DX3065 RMT Ltd 3 4 Theory of Operation Z measuring of a Two stage TEC Hereinafter we deal with the stationary mode values only see Ch 2 The general formulae for a two stage module cold2. RMT Ltd DX3065 The order of data arrangement in the History window is represented below L History Neyo po pom poro fe re e jz 1MCO4 00415 400 17 00 70 0 1 60 EG 1MCO4 008 05 400 17 00 30 0 1 60 av 1MCO4 008 05 40 0 17 00 20 0 1 60 The Chk field is sacred for records marking Only marked records will be copied on a printer under the Print command The marking unmarking is performed with the mouse left button click on the appropriate field The default condition is Marked Working with Z Meter 5 21 DX3065 RMT Ltd 5 10 Database Update If the parameters of a TE cooler you are going to deal with are not introduced in the database you must add them yourself To do it you should first of all find out the following parameters of TE cooler e TEC cold size dimensions e The number of pellets for a two stage TEC the pellets number at each cascade e TE pellet cross section e TE pellet height e TEC wires material e Wire length e Wire thickness If there are no these parameters in the manufacturer s specification you can measure them yourself by means of slide gauge Jiz Meter TI 1 0 File Options History Help Coo TEC Base Editor 05 Amt Mode a e RMT BASE Cooler type KOMATSU BASE After you have prepared all the necessary data select the Options TEC Base Editor command from the Cooler menu The window titled Add TE cooler will 5 22 REV 1
3. Aa we Joint Stock Company Z Meter TE Module Parameters Meter DX3065 Series User Guide 2002 Rev 1 00 DX3065 RMT Ltd Edition July 2002 Copyright All right reserved Reproduction in any manner in whole or in part is straightly prohibited without written permission of RMT Ltd The information contained in this document is the subject to change without notice Limited Warranty RMT Ltd warrants that DX3065 Meter if properly used and installed will be free from defects in material and workmanship and will substantially conform to RMT s publicly available specification for a period of one l year after date of DX3065 Meter was purchased If the DX3065 Meter which is the subject of this Limited Warranty fails during the warranty period for the reasons covered by this Limited Warranty RMT at this option will REPAIR the DX3065 Meter OR REPLACE the DX3065 Meter with another DX3065 Meter Trademark Acknowledgments All trademarks are the property of their respective owners RMT Ltd 53 Leninskij prosp Moscow 119991 Russia phone 095 132 6817 fax 095 132 5870 e mail rmtcom dol ru http www rmtltd ru REV 1 00 2002 RMT Ltd DX3065 Contents 1 Introduction 2 Principle of Time Constant Measuring 2 1 Theoretical Grounding 2 2 Interpolation Results 2 3 Theory of Operation 3 Principle of Figure of Merit Measuring 3 1 Theory of Operation Single stage TEC wWOwWwW
4. Boltzman constant y thermal emissivity Principle of Figure of Merit Measuring 3 3 DX3065 RMT Ltd At the heat exchange with environment aj P _ lt k N 3 5 and the current k I lt a 3 6 we have 2 do a la Ua _ YA T I RN ji 0 1 3 7 UR Qg Q 2k aotaj where Ux A T Ty thermoelectric component of the voltage dropout on a TE module the seebeck voltage Ur IR Ohmic component of the voltage dropout on a TE module 2 _ Q KR Equation 3 7 contains directly the ambient temperature If using the average temperature we should have allowed for the additional term a 2Nk characterizing heat dissipation from the external surfaces Formula 3 7 takes this term into account automatically via the ambient temperature value 3 4 REV 1 00 2002 RMT Ltd DX3065 Consider the equation for Z 38 7 The second term in 8 7 generates a certain correction It is remarkable however that this term is a linear function of the current As a consequence summing the 2 Ua 1 2Z Fane 3 8 OF A Uk a a That is we managed to solve the problem avoiding any asymmetry correction challenge So the value Z A KR could be obtained as YO 14 by b s P Ta 1 b Ur b averaged where Correction factor to ambient temperature due to Joule heating _ 1 IRN zi Ta Ata 3 9a Principle of Figure of Merit Measuring 3 5 DX306
5. The window of the standard Windows installer will appear Fig 5 1 Working with Z Meter 5 1 Pass all the steps of the installation procedure sequentially according to the installer directions When selecting the logic disk you must keep in mind that the program requires not less than 2 Mb of hard disk space As database size increases the additional disk space can be required setup will install the software to the directory listed in the box below To install to a diferent directory either type in the new path or click Browse to select another directory Install files to this location C Program Files 2 Meter Browse Space required on drive 1 9 MB space available on selected drive 406 ME Cancel Fig 5 1 The Z Meter installation window 5 2 REV 1 00 2002 RMT Ltd DX3065 5 3 Hardware Preparation Turn DX3065 Meter back side to yourself From this Side you will find out the following elements Fig 5 2 e Power ON OFF button e LED power indicator e Power supply input connector e RS 232 connector LED power Indicator Fig 5 2 The back side of DX3065 meter Working with Z Meter 5 3 1 Make sure that the DX3065 is switched off 2 Using the DX3065 C 01 cable connect DX3065 Meter to COM port which you are going to use for DX3065 Fig 5 3 RS 232 interface driving Fig 5 3 cable connection 3 Connect the AC DC adaptor to Power sup
6. 00 2002 RMT Ltd DX3065 appear as shown below There are two input boxes in the window Cooler and Leads All fields are beforehand filled in with defaults You should enter the true values of parameters in them The contents of cooler ID field are not used for calculations You can fill any information in this field but you had better enter there the manufacturer s brand Cooler Cooler ID EGET Cooler type 8 Single stage a j z iO a gu Wo lel lal Cold size dimensions mm mm Hot size dimensions mm ss mm Ceramics thikness mm Pellets number TE pellets cross section mm mm m oy o o TE pellets height mm Leads Electrical resistivity E 6 Ohm x mm Length mm JI Thickness mm Cancel Delete Sad adi After all the fields in both boxes are filled in with the appropriate data click on Add Modify button Working with Z Meter 5 23 DX3065 RMT Ltd To remove the record concerned some TE cooler from the database select it from the Cooler ID list and click on the Delete button REV 1 00 2002 5 24 RMT Ltd DX3065 6 Maintenance The DX3065 Meter does not require any maintenance or service Nevertheless if for any reason you feel doubtful about the device s accuracy you can check up it by measuring a precision resistor instead of a TE cooler It is best to measure a resistor of 5 to 20 Ohms Ifa precision r
7. and hot sides are l Ty 1 R K T T T 1 2 N l a 3 16 IT I R k T T T T 2 N where To Ti T2 TE module s cold side medium and hot side temperatures respectively Ni N pellet numbers at the first and second stages Ifitis possible to assume that the heat transfer coefficient a and the pellets number N are proportional to the corresponding cold side areas S ei eee A const 3 17 N N 3 10 REV 1 00 2002 RMT Ltd DX3065 and S B const S 3 18 equations 3 16 are modified the following way aT R k L T ATT 3 19 alT IR K T T A T T Summing up equations 3 19 we derive 201T k A AT 3 20 N where T is the average module temperature solving the following set of equations 201T k A AT 1 Ur Up I l i 2 AT Co Vo a N N Principle of Figure of Merit Measuring 3 11 DX3065 RMT Ltd we obtain the following ZT 1 b 1 b 3 22 R b Boond Aronw Brag Aig 3 23 The parameters Boong Braqa are described above 3 4a 3 4b POE 3 24 KB Arad OTAI 3 25 ra KB where Acon Araq Stand for convection and radiation external heat transfers respectively The problem stated by eq 3 16 is polarity symmetrical So the averaging of the different polarity voltage ratios for accuracy conc
8. is a window title It s header consists of constant and variable parts The constant part includes the application name and revision number The variable one points to the TECs measuring option selected 5 5 2 Menu bar There are four commands in Menu bar 5 8 REV 1 00 2002 RMT Ltd DX3065 e File is used when it is i 2 Meter 11 1 necessary to reconnect the File ptions His Device or exit Reconnect Exit e Options command 225 _ Meter II 10 allows to File Options History Hele 1 add edit cooler type Coo TEC Base Editor 2 select a TEC database Amt TEC Base Cooler type History command allows to view the list of current measuring session results stored in the History file Help command allows to derive the information concerning Z meter program Working with Z Meter 5 9 DX3065 RMT Ltd 5 5 3 Reference Bar There are two fields in the Reference bar The left field Cooler type ID in the Reference bar is a list box for selecting a TE cooler type to be tested The right field Reference T in the Reference bar serves for reference temperature input You may type any reference T directly in the window or increment decrement the current value by 0 1 with the and buttons Besides that you can click the right mouse button inside the Reference T input field The following list must fall down Reference T C ZO ger erature C anor
9. on average This time is approximately enough to stabilize the TE cooler temperature see Chapter 2 Working with Z Meter 5 17 DX3065 RMT Ltd It may happen that after clicking the Measure button the following message appears PS Aa x Measuring Failed Check TE Cooler This message means one of the following e open circuit inside the TE cooler e short circuit inside the TE cooler The latter reason is practically improbable so really only the first one can occur Check the terminals Maybe the contact is poor Retry measuring If still you see the same message the TE cooler must be rejected As it was mentioned above the DX3065 Meter can be applied for more than two stage TE coolers quality checking by measuring electrical resistance To do this leave the TE Cooler Type unselected Default Type in the TE Cooler Type field Insert a TE cooler into the DX3065 Meter and click the Measure button You should ignore all the results except the resistance one 5 18 REV 1 00 2002 RMT Ltd DX3065 5 4 4 metering of a Single stage TEC on the Heat Sink All the information presented above for Option 1 remains true except for the Heat Sink Parameters Field With the help of these parameters the corrections are calculated allowing for Formula 3 9a c and 8 15 5 8 Z metering of a Two stage TEC All the information presented above for Option 1 remains true except the follo
10. 5 RMT Ltd Correction factor to pellet thermoconductivity due to Boong 3 9b additional heat flux from the bin Beond Brad warm side to the cold one through the medium according to 38 2 Correction factor because of a non zero resistance of TE module wires 3 9c Rrec where Rrec NR The total voltage drop Urisa sum of the drop Urec at the module and some additional drop at terminal wires r is their resistance so Uk I Rrec r IRrpc 1 b 8 10 UR Ur i 5 3 11 Due to the above formulated correction factors eliminate the effect of actual arrangement of Z metering technique on the Z value and allows to estimate the true material Figure of Merit 3 6 REV 1 00 2002 RMT Ltd DX3065 3 2 Figure of Merit and ATmax for Single stage TEC The Z value corresponds to the maximum temperature difference on a module AT by a simple ratio AT max 521 3 12 However the direct measurement of Ty is complicated A more convenient way is to measure the temperature difference through the hot surface temperature 77 T T AT If the heat sink thermal resistance is little the hot side temperature approaches the ambient temperature and T T is used instead of 7 Max Hence there is the following equation for AT jax 1 AT max ii Z Ta AT max 3 13 Then it is easy to recalculate the value AT mnax as a function of the ambient temperature
11. Ambient T You may choose one from standard reference temperatures 20 and 30 C or use the ambient temperature as a reference 5 10 REV 1 00 2002 RMT Ltd DX3065 5 5 4 Functional Fields There are four functional fields e Control field presents the Seebeck voltage temporal behavior and Z metering input parameters see Chapter 2 1 measuring current 2 total measuring time 3 time step Control Current mA E hi a Measuring Time sec f 0 0 v a Time Step msec fao v al The Measure button starts the measuring procedure e Dynamics field presents the Seebeck voltage temporal behavior telemetry chart window see Chapter 2 Ua t measured and interpolated at different current polarities 04 0 000 84 1 80 2 60 3 60 4 50 5 40 6 30 7 20 8 10 9 00 9 90 time sec Figure of Merit 2 50 2 60 1000 K Time Constant 1 60 1 60 sec It also provides obtained values 1 Time constants at different current polarities 2 Z at different current polarities Working with Z Meter 5 11 DX3065 RMT Ltd e Corrections Coefficient field includes calculated corrections values see Chapter 3 It allows to switch a certain correction ON or OFF As an alteration it provides the corrections compounding into a general coefficient a see Formula 8 28 Corrections f Default 1 05952 I Inter pellets input 0 05775 M Joule heating 0 00006 M L
12. Table 5 1 You are able to switch this or that correction on off with the help of corresponding radio button pairs on the Corrections field The Results window fits the changes automatically Table 5 1 Corrections for the One stage option calculated by 3 9a c for the Two stage option calculated by 8 22 3 25 excluding the Joule heating correction Ua 1 Correction factor showing Joule heating br energy dissipation ratio Correction factor to pellet thermoconductivity Inter pellets due to additional heat flux from the warm side to input Correction factor because of non zero resistance of TE module wires 5 16 REV 1 00 2002 RMT Ltd DX3065 By default the Results field data are calculated with all the corrections switched ON in the Corrections field These corrections are equivalent to a certain coefficient a The latter is described in formula 3 28 The Coefficient Mode Field allows a User to apply either the coefficient calculated within all the ON corrections Default Mode or to offer one s own coefficient Manul Mode or to refuse any corrections and therefore set the coefficient equal one 5 6 4 Measurement Notes Important The temperature of a TE cooler changes slightly owing to a hands touching Also the measuring procedure induces slight cooler temperature increasing So maintain a pause of about this test 3 time constants before the next one It is 30 seconds
13. after another SEARCH DX3065 DX3065 FOUND Then the window as shown in Fig 5 7 will appear If the following message appears DX3065 NOT FOUND make sure you have switched on the device and have the COM port and device cabled and retry REV 1 00 2002 5 6 LO 9 MM gt L O Ploy 01 u09 Play soiumeukg urerbord 1939 Z JO MOPUIM urew OJ 7G Olt a OO 484 S906x d uw RRR RRR RRR RRR RRR RRR RR ee ee a Me ee el a desu dyg Solu 235 aW Gunnseaji yu yua Ins gas lec 6r Z 7H Hejun awi Modo 6k te dig i Wayyqo aunbiy sas SWI OOSE OO LE OO S9E OO Le OOS OO LL OBS 0 E20 0 a rozl 3 1 aauaiayay auon j t Enue j zalm Dupes A Buneay amor Al dui sajad aju Al LLAD L AE aj sO IaNO7 Sl Cc S 6S 90 C Pe wyg Sue Jas JUBYSUOT au I 60C 3 Sinjejadwa juaIquis yy ameadwa yuaguy neeg gi ada 13 007 daH AoA suoda aji OT 1 4229 27 AFLOO 29200 EEDI PIJIJ JU9191JJ909 SUOI 991105 5 7 Working with Z Meter DX3065 RMT Ltd 5 5 The Main Program Window The main program window is shown in Fig 5 7 Its functional structure is common for three Z meter measurement options e Single stage TEC measuring e Single stage TEC mounted on a heat sink measuring e Two stage TEC measuring This general window includes the following 5 5 1 Title The narrow band at the top of the Main window
14. are connected under the four wire Kelvin Clips scheme Simplified Functional Diagram of DX3065 Meter is shown in Fig 4 1 I Instrumentation 1 amplifier I Fig 4 1 Simplified functional diagram of DX3065 Meter Technics 4 1 DX3065 RMT Ltd 4 2 AC Resistance Measurement For resistance measuring the module is tested by AC of a small amplitude The AC is simulated with the Commutator which periodically with 50 duty circle reverses a circuit of the reference current In The simplified diagram of the Commutator is shown in Fig 4 2 sa cee Inthe noinputsignal Fig 42 The simplified state the output diagram of AC resistance voltage of the measuring Instrumentation Amplifier IA is equal to E 2 where E 4 096 V Fig 4 3 Un Up Un Fig 4 3 Output signals of Instrumentation Amplifier at AC resistance measuring 4 2 REV 1 00 2002 RMT Ltd DX3065 During AC resistance measuring the output voltage of the IA is sampled and measured by 12 bit ADC every time before current reversing The sampling points are marked as t in Fig 4 3 The voltage drops on TE module when positive current Up and negative current Un are used for a TE module resistance R calculation under the following formula n R 4 1 P A Ln z Ay Nn where Up voltage drop on TE cooler at positive testing current In Un voltage drop on TE cooler at negative
15. ce T list If there is no required reference temperature in the list 5 14 REV 1 00 2002 RMT Ltd DX3065 5 6 2 Cooler Type Jz Meter 11 1 0 File Options History Help Cooler type ID Choose a type of TE cooler to i E Default Ambient Temper EETA be tested from the Cooler haee type ID list The list TMCO4 004 10 1MCO4 004 12 represents a TEC base 1MCO4 004 15 Time Constant sq IME UE 6 selected via the Options J Ee TEC Base command RMT eee is the default TEC base 1MCO4 012 05 21 2 05 The following windows reports that one ore more fields of the TEC base string selected is are blank Information ET P Some parameters are missing No corrections will be applied Keep in mind that the TE coolers list is sorted alphabetically If you cannot find the necessary type in the list you should introduce TEC parameters to the database manually See Chapter Database Update If you have no information on parameters of the tested TE cooler you may choose the corrections coefficient default mode and the TEC will be measured excluding any corrections Working with Z Meter 5 15 DX3065 RMT Ltd 5 6 3 Corrections Field Once the measuring procedure is completed you can see the obtained corrections and results in the corresponding fields With all TEC parameters available all the corrections are taken into account by default The corrections are specified in
16. eading wires 0 00769 C Manual 1 C None For this coefficient determination it allows to choose one of the three following approaches Default Using the corrections calculated in the corrections field Manual Using a User s own coefficient value None Using neither corrections nor coefficients at all e Results field contains measured calculated results 1 TEC ACR 2 Ambient temperature 5 12 REV 1 00 2002 RMT Ltd DX3065 3 TEC figure of merit averaged via the values calculated in the Dynamics field 4 TEC maximum delta temperature Ambient Temperature F Ambient Temperature LC 298 2 25 1 Time Constant sec 1 60 Maxinun DT K Figure ot herit 1000K 605 2 50 The window besides implements the function of the status indicating device Working with Z Meter 5 13 DX3065 RMT Ltd 5 6 Single stage TEC Z metering To measure a single stage TEC select a Single stage option from the Option gt gt Cooler Type command 5 6 1 Reference The parameters of TE coolers can be measured at various ambient temperatures The indications of DX3065 Meter will be varied with temperature See Chapter 3 Principle of Operation Hence measured parameters must be corrected to some reference temperature RMT Ltd uses 30 C reference temperature other manufacturers may use their own values Choose a reference temperature from the Referen
17. erns is appropriate So eq 3 22 can be rewritten as a Up averaged ee Knowing the Z value we can evaluate ATmax T To ZT 1 b 1 b finding the maximum of the following function 3 12 REV 1 00 2002 RMT Ltd DX3065 x 1 2Z x 1 1 x 6 1Xx 1 1 3 27 AT x T x x x I 81 2Z x 1 where N M NJ the cascading coefficient al x z dimensionless current For instance if Z 0 0027 K and T 300K we have the following temperature difference AT 100 K 3 5 Material Z and measured Z Regarding all the correction factors discussed above it is clear that the material Figure of Merit when there is no heat exchange with environment is always higher than the measured Figure of Merit It is convenient to relate the two values via the coefficient a gt 1 Z a Z medsured 3 28 Principle of Figure of Merit Measuring 23 13 DX3065 RMT Ltd REV 1 00 2002 RMT Ltd DX3065 4 Technics 4 1 DX3065 Meter Arrangement The body of the DX3065 Meter is made of an aluminum alloy The metal body executes a function of a passive thermostat for measured modules Temperature of the body is measured with digital thermometer with accuracy not worse than 0 1 C A module to be measured is placed in this box The connection of the module is made through special connectors For a reduction of the effect of contact resistance the modules
18. esistor is not available any other can be used But at first it should be measured with a digital multimeter with the accuracy not less than 3 decimal digits Compare the obtained data If the difference in the resistance values is within 0 5 it is possible to consider the Z Meter serviceable Maintenance 6 1 DX3065 i Standard Kit RMT Ltd Item Code Quan l Z Meter DX3065 l 2 AC DC Adaptor 3 RS 232 Cable DX3045 C 01 l 4 CD with software Z Meter l 5 User s Manual l 7 1 REV 1 00 2002 RMT Ltd 8 Specifications Measured parameters Electrical Resistance Range Accuracy Repeatability Thermoelectric Efficiency Range Accuracy Repeatability Supply reguirements Supply voltage Supply current Operation conditions Temperature range Relative humidity Mechanical Dimensions Weight Specifications DX3065 0 1 to 100 Ohms 0 5 0 3 1 5x10 K 0 5 0 3 7to 9VDC 250 mA max 0 to 45 C 0 to 95 60 x 35 x 135 mm 310 g max 8 1 DX3065 8 2 RMT Ltd REV 1 00 2002
19. of Merit is the most important performance parameter of a TE cooler It is defined as Ve 3 1 KR where a TE material Seebeck coefficient k thermal conductance of TE pellets material R Ohmic resistance of TE module Principle of Figure of Merit Measuring 3 4 DX3065 RMT Ltd From this time on we deal 77 with the stationary mode 7 values only see Ch 2 Tv os 4 The base equations that o a Tilt describe a one stage TE 4 module power balance ay aT PR k AT a 1 mi 3 2 alT I R k AT a 2 N where Ty cold surface temperature T hot surface temperature AT T Tp T ambient temperature I current passing through TE module N TE pellets number d environment cold side heat transfer term a environment hot side heat transfer term k effective pellets thermal conductance 3 2 REV 1 00 2002 RMT Ltd DX3065 The term k describes thermal conductance normalized to one pellet between the cold and hot surfaces k k 1 bth 3 3 where Din Beond Brad 3 4 The Beong and B aq are corrections for inter pellets thermal conductance values through air thermal conductivity and radiation respectively Beond K air 1 r 3 4a K P Here the pellets filling term is Ns B o S where s a pellet cross section S the cold side area Brad Y 2 T 7 B 3 4b Nk where O
20. ply Input Fig 3 4 4 Push Power ON OFF button and turn the Meter on 5 Turn on your computer if it was off Now you can run the Z Meter program and measure parameters of TE coolers connection 5 4 REV 1 00 2002 RMT Ltd DK3065 5 4 Measurement of Parameters of TE coolers Before measuring it is necessary to keep the DX3065 Meter and tested TE modules indoor during one hour in the same room where TE modules will be measured This is necessary to even temperature of TE modules and DX3065 Meter Important If the DX3065 Meter was outdoor at low temperature for a long time temperature below 10 C it is necessary to keep Z Meter at room temperature for not less than 2 hours Press the handle down Fig 5 5 and open the cover of the DX38065 Meter There are six terminal blocks underneath The first three are intended for one lead of a TE cooler the other three for the other lead Fig 5 5 Cover unlock handle Turn the arm type buttons of those contacts that best correspond to the TE cooler size and insert the leads into holes Fig 5 6 The polarity has no meaning as the coolers are tested by bipolar averaging Fig 5 6 TE coolers s leads insertion Working with Z Meter 5 5 DK3065 RMT Ltd Close the cover and run the Z Meter program If you run the Z Meter program for the first time after the program setup the following windows will be displayed one
21. ribed by a multi exponential interference This stage fades out rather quickly and in case TEC pellets thermal conductance is high enough the temporal behavior can be characterized by the only exponent 1 e M pin lt lt Mn 2 2 for all possible indices n The theory yields the following expression for the time constant t 1 Mmin Of single stage TEC s Te Las 2 3 1 Ja K where C TEC cold side heat capacity Ol the thermoelectric TE material Seebeck constant K the TE material thermal conductivity N the TEC pellets number L the pellets length S their cross section j the electric current density 9 5 REV 1 00 2002 RMT Ltd DX3065 As 2 3 shows t calculation is stumbling because in practice the values involved in it are never known to the proper accuracy extent The DX3065 allows to measure the time constant of single stage TEC s and to estimate that of more stage ones 2 2 Interpolation Results The procedure of handling the time constant measurement data is as follows The temporal behavior of a single stage TEC temperature difference is measured via the Seebeck voltage that is a corresponding proportional value U aAT 2 4 For a two or more stage TEC this simple ratio is not applicable However the time constant can be estimated by the temporal dependence of the Seebeck voltage and the approach for obtaining the stationary vol
22. rious types of single and two stage TE modules Additionally it is possible to evaluate quality of three or more stage TE modules by the measurement of electrical resistance Although the above listed parameters are measured at ambient temperature DX3065 Z Meter provides recalculation of them to any standard temperature 20 C or another software selectable The DX38065 Meter is managed by any IBM compatible computer under Windows95 98 2000 operating system Introduction 1 1 DX3065 RMT Ltd 1 2 REV 1 00 2002 RMT Ltd DX3065 2 Principles of Time Constant Measuring 2 1 Theoretical Grounding Let us consider a one stage thermoelectric cooler TEC The ambient temperature is 7 At a certain moment the electric current in the TEC is turned on The differential equation result for the TEC transient dynamics can be presented as the following exponential superposition AT t x S 4U x e AT x 2 1 i 1 where AT t x T T T is the temperature of the TEC point located at a time and a generalized coordinate x U and m are the eigenfunctions and eigen values A are the thermal amplitudes ATs x is the stationary result value The solution 2 1 analysis yields that the cooling process can be divided into two stages irregular and regular The first one is dictated by the initial moment s Principles of time constant Measuring 2 1 DX3065 RMT Ltd conditions and is desc
23. tage values is the same The measuring procedure is carried out both for two electric supply polarities The data collection duration and time step can be varied The measuring chart window is presented in Fig 2 1 Principles of time constant Measuring 9 3 DX3065 RMT Ltd 0023 30 6 90 11 00 16 00 21 00 26 00 31 00 35 00 time Sec Figure of fwlarit He 2 17 21 19 000k Time Constant 4 1 249 247 sec Control Current mA 30 Measuring Time sec 40 0 a Time Step msec 20 z Fig 2 1 Measuring window of Z Meter program The obtained experimental data is then fitted by the following function U t Ust d e 2 5 The exponential regression is based on the method of least squares As its outcome the procedure provides the time constant t and the stationary Seebeck voltage Usta 24 REV 1 00 2002 RMT Ltd DK3065 3 Principle of Figure of Merit Measuring 3 1 Theory of Operation Single stage TEC Among three parameters R Z AT max measured by DX3065 Meter only AC resistance R is measured directly The R measurement method is described in the Part AC Resistance Measurement of Chapter 4 The determination of the Figure of Merit Z and the maximum temperature difference ATmax of a thermolelctric TE module implements an indirect method which allows to avoid labour consuming thermophysical measurements This approach is based on the Harman method The Figure
24. testing current J Im testing current Ay voltage gain of Instrumentation Amplifier n total number of samples per measurement The typical values of parameters in formula 4 1 are as follows Tn amA Ay 5 or 50 n 50 Technics 4 3 DX3065 RMT Ltd 4 3 U and U Measurement At measurement of U and U parameters the small current Iris applied to a module periodically with 50 duty circle Two successive measuring sessions are necessary to obtain the U and U values at different testing current polarities Testing current I ee uu ee es A Pe TEC total and Seebeck voltages Fig 4 3 Test current and voltages schematic temporal behaviour 4 4 REV 1 00 2002 RMT Ltd DX3065 5 Working with Z Meter The DX38065 Meter works under the control of the Z Meter program The Z Meter program provides all possible operational modes of the DX38065 Meter The Z Meter has the simple interface and does not demand a User s special knowledge The Z Meter software is delivered with the DX3065 Meter 5 1 System Requirements e IBM PC compatible computer with Windows 95 98 2000 operating system e Free COM port e 2 MB free hard drive space additional space may be required later as your database grows e Mouse or compatible pointing device 5 2 Program Installation Z Meter is supplied on CD Insert the CD into the appropriate drive and start the setup program
25. wNDNHDND PND DY e RK O WO m 3 2 Figure of Merit and ATmax for Single stage TEC 3 3 Theory of Operation TEC mounted on the 3 8 heat sink 3 4 Theory of Operation Z measuring of Two stage TEC 3 5 Material Z and Measured Z 4 Technics 4 1 DX3065 Meter Arrangement 4 2 AC Resistance Measurement 4 3 U and U Measurement 5 Working with Z Meter 5 1 System Requirements 5 2 Program Installation 5 3 Hardware Preparation 5 4 Measurement of Parameters of TE coolers 5 5 The Main Program Window 5 5 1 Title 5 5 2 Menu bar 5 5 3 Reference Bar 5 5 4 Functional Fields eo 00 1 CO CO o O WF e e KB D e e O1 O1 01 OI OI OI OI OI OI C1 A A A A O ka Contents DX3065 Contents KE 5 6 Single stage TEC Z metering 5 6 1 Reference 5 6 2 Cooler type 5 6 3 Corrections Field 5 6 4 Measurement Notes 5 Z metering of a Single stage TEC on Heat Sink 5 8 Z metering of Two stage TEC 5 9 History 5 10 Database Update Maintenance standard Kit specifications RMT Ltd REV 1 00 2002 RMT Ltd DX3065 1 Introduction The DX3065 Z Meter provides precise measurement of Thermoelectric modules parameters e AC resistance R o Figure of Merit Z maximum temperature difference A Tmav e time constant Using DX3065 Z Meter it is possible to perform testing of va
26. wing 1 A default Cooler type does not allow to estimate ATmax because for this purpose the cascading coefficient value is necessary 3 The Corrections field is the same but the corrections values are calculated differently for this case see formulae 8 22 3 25 2 For a two stage TEC ratio 2 4 is not applicable and the time constant can be only roughly estimated by the temporal dependence of the Seebeck voltage Working with Z Meter 5 19 DX3065 RMT Lid 5 9 History The outcomes of each measurement are stored in the file You can view or clear it using the History command The history file is created in the History History folder of the Z meter directory in every measuring session after the first successful measurement Measuring session means the period between the first successful measurement and the program exit The history file name has the form of the date and time of the history file creating If you need to add some title comment or any other additional short information into the history file you must type it in the Comment field on the top of the History window If you need to save the History file with another name use the Save command With the Print command you can make the hard copy of the History file on a default printer The New command closes the current history file and opens a new one with no data 5 20 REV 1 00 2002
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