TC-M Lite User Instructions v1
Contents
1. 12 7 6 6 Maximum Temperature Only available on certain GU I 12 1 7 A taal ch ul hen ae asf eau los ics lane 12 FLA A ri dotan 12 TE A O 12 Tla ONO A E a A 12 A e e a a aves a a aa eaa 12 TEES MS A A A a EINER 12 MOn Fr UI 3st ech gs hc alee aca a A a nha SIAR 12 Ll Temperature Orta ida 12 7 8 Reading and Setting Para ui ee vated 13 A us oR atm ia a unas tise aac 13 ER basset eaea e Eee alent Eae a Eaa EEA ane 13 cg Figure TC M series Temperature Controller GUI Java 13 PMO NORE OU ee scree E E EE EA ameesle reams E EEE 14 7 10 1 Additional e eS li id 14 140 2 Dato rr e a N ats 14 IO EAU o o e 14 87 Communication Protocol ressis aa ie a a a aa 15 9 Specification TC M NA A A nranti 16 9 1 SUPP earn a E A 16 9 2 Output a ian essa deta o a aa a a 16 9 3 o A E E Me ce cot ack a at 16 9 4 A aces sous scaretnieaese canttasun sages saaateran A E E 16 9 5 AM cp Sexe ora anu sata acme x ab 16 9 6 SENS ON cc Ber eee gi td OS 16 9 7 Measurement ACCUFaCCY tratada detail 16 9 8 Uri NS A A tata ten A 16 9 9 A an testa mca aay aeolian aim esa ot neste Rana 17 10 Sourc sot Information peana apa 17 Electron Dynamics Ltd page 2 TC M Lite Temperature Controller User Manual V1 08 1 Introduction Our TC M Lite series of Temperature Controllers are designed for use with thermoelectric coolers also known as TEC s or Peltier devices These offer precise temperature contro2. TC M Series Temperature Controllers V1 08 Electron Dynamics Ltd Kingsbury House Kingsbury Road Bevois Valley Southampton SO14 OJT Tel 44 0 2380 480 800 Fax 44 0 2380 480 801 e mail support electrondynamics co uk TC M Lite Temperature Controller User Manual V1 08 Index O gs AA ci oles Te ee hath aaa E ERE 1 Ziv Controle FUNCION ica o atea 2 2 1 SENS OM measurement aaa 2 2 2 CPU os ars A A nt Aol Pane Madea stds 2 2 3 CUP 2 2 4 Communication Starr date 2 2 5 TEC OU A TE A Saleen bend 2 A A A E A lane Meciatobones eae 3 3 1 PT100 and PT1000 Measurements urinaria 4 3 2 Voltage sensor Measurement 4 3 3 NT MEM titan 4 3 4 Other temperature Senso Sui ali 4 3 5 A O enter vot at ner O A 4 3 6 Power connection tae 4 3 7 Alarm Outpt a GAO 4 3 8 A A O Error Bookmark not defined 3 9 A nhs a teeta lute pies eS Aca et a ate E cece ET 4 A E etch dante uite casa tals 4 5 he rmal NS aio aia 5 5 1 Sensor Selection Error Bookmark not defined 5 2 A O II E a a A 5 5 21 A a a e cai 5 5 3 Thermal Conduction con 5 5 4 Peltier SIZE siria a A 5 5 5 Drive LiMihiyr seske a da E cata ee aly 5 5 6 Important stability SSUES ooooocononncnonnocccnncccrcnnrnrnrnrcrnrcrnrnrroronrnrnnnnos 6 6 Temperature Controlling a a A a 6 6 1 A mer react ere mrt nr nee eet R 6 6 2 OO cti ad 6 6 3 a A A Ma er E cel ped 6 6 4 Tuning the PID Parametros 7 6 5 Temperature test MOE cccccccscssse
3. Span s 30 Test time s 0 Electron Dynamics Ltd 14 TC M Lite Temperature Controller User Manual V1 08 7 Communication Protocol Please see the commands file on the resources CD ROM Electron Dynamics Ltd 15 TC M Lite Temperature Controller User Manual V1 08 8 8 1 8 2 8 3 8 4 8 5 8 6 8 7 8 8 Specification TC M Series Supply 5v to 28v DC Output 0to5A TC M Lite 5A 0 to 10A TC M Lite 10A Bi directional heating and cooling Variable output Oto 100 0 1 resolution PWM rate variable 20Hz to 1000Hz Control From PC via USB Programmable PID terms Will operate as P Pl PID or On Off with Hysteresis Resolution 0 05 C Max stability 0 05 C depending on thermodynamics setup Set point Set either by pot or by PC Alarm PC configurable TTL output active low High temp Low temp or out of band Sensor Voltage PT100 PT1000 LM35 LM50 LM60 LM61 NTC Thermistor OTHER Other versions can be calibrated using the quadratic coefficients Measurement Accuracy PT100 0 05 C or better LM35 etc 0 05 C or better User Windows control software allows access to all parameters Can be controlled within a process environment Electron Dynamics Ltd TC M Lite Temperature Controller User Manual V1 08 8 9 Format PCB assembly or Module 9 Sources of Information For further information on the operation of temperature control peltier units http
4. GUI has feature for test mode temperature cycling and temperature ramping also included is an auto tuning algorithm for setting up the PID terms automatically 6 10 2 Data Logging This function enables disables a continuous stream of temperature and output information from the TCM controller This is stored in a log file for compatible with excel for analysis This allows the user to measure response graphs for tuning and stability analysis 6 10 3 C GUI LTEM 1 5d Electron Dynamics Ltd 10l x Sensor Setpoint Pot y Method fas Value ficooo Rat 25 100 fos Coeff fo Potoffset pmm 22000 RI Pot range c y Unit Off Averaging Read Test Modes Off Test type Control type Gain Integral Derivative Derivative TC Dead band Power Up State Bar Write Output Alarms Positive y 100 0 Min 100 0 Max o Frequency Polarity Min Max 5 50 off v Temp OK margin 0 5 Min jO 5 Max Operational temp limits 0 Min 70 Max Read Write 7 Control Output Off Control Read Run Not running Output Temperature Data Logging Start log dat t File not open R Parameter File Read TCM_setup_file xls Write File not open Setpoint Temperature Control Output Alarms Faults Temperature OK TCM version MNI F Continuous Temperature Graph Temperature 30 it Time s
5. enable 6 6 2 Maximum Alarm Sets the temperature above which the alarm is activated Select via check box to enable 6 6 3 Minimum OK Temperature Sets the lower temperature difference point from the set point for temperature OK 6 6 4 Maximum Temperature Sets the higher temperature difference point from the set point for temperature OK 6 6 5 Operational temperature max Only available on certain GUI Sets the temperature maximum above which the drive output is disabled 6 6 6 Maximum Temperature Only available on certain GUI Sets the temperature minimum below which the drive output is disabled 6 7 Report 6 7 1 Set point Displays the set point can be used to ensure the controller has accepted the set point entered in the control category refer to section 5 3 6 7 2 Temperature Displays the measured temperature the measured temperature units can be Celsius Fahrenheit or Kelvin and can be selected in the sensors category refer to section 5 4 3 6 7 3 Control Displays the condition of the output drive either On or Off 6 7 4 Output Displays the output value is set to Range 0 to 1000 6 7 5 Alarms Displays whether an alarm is active 6 7 6 Faults Displays any fault codes 6 7 7 Temperature OK Displays if the temperature is in the ok range Electron Dynamics Ltd page 12 TC M Lite Temperature Controller User Manual V1 08 6 8 Reading and Setting Parameters 6 8 1 Read Button The read butto
6. with minor differences The GUI will be broken down into eight functional categories each will be explained in the remainder of this section of the manual Pull Down Menus Il Control Ill Set Point IV Sensor V Output VI Alarms VII Report 6 1 Pull Down Menus 6 1 1 File Menu Save as defaults allows the user to save a copy of the current GUI set up which can be loaded using the load defaults command The exit command closes the GUI 6 12 Port The desired communication port can be chosen and the TCM Series Temperature Controller can be connected or disconnected Please note port needs to be selected and opened at the outset in order to communicate with the controller 6 1 3 Help Displays help information Electron Dynamics Ltd page 8 TC M Lite Temperature Controller User Manual V1 08 6 2 Control 6 2 1 Type The control algorithm can be single or a combination of Proportional Integral Derivative terms The list box allows the user to define the controller terms required The available options are 0 None 1 On Off 2 Proportional 3 Proportional and Integral 4 Proportional Integral and Derivative User defined values can manually be entered here for the controller to operate from 6 2 2 None This is a default off mode for diagnostic or fail safe purposes 6 2 3 On Off With On off control the output drive is only fully on heating or cooling or off Its response is Temperatu
7. www peltier info com TEC information site http www marlow com TEC manufacturer http www jashaw com pid Control E book http www jashaw com pid tutorial pid6 html PID tuning lecture notes http lorien ncl ac uk ming pid PID paf PID notes Electron Dynamics Ltd 17
8. 1 6 2 8 Dead band For use with On Off control the dead band specifies the temperature range around the set point where the output is zero 6 2 9 Power Up State This sets the temperature control state from power up where this can be set as On or Off or where Last is selected it sets its last setting prior to power off 6 3 Set point 6 3 1 Method The temperature set point can be set via the PC or by altering the pot on the TCM series Temperature controller hardware For setting via the PC select the PC radio button and enter the set point value into the edit box directly following the radio button 6 3 2 Pot Range This sets the temperature range that the pot gives values for 6 3 3 Pot Offset This sets the minimum temperature point on the pot 6 3 4 PC Set Point This allows the set point to be fixed via the GUI 6 3 5 Control The control radio button if checked inhibits the temperature control 6 3 6 Output The output edit box allows a fixed output to be set To use this control should be disabled otherwise any setting made will be over ridden by the control Range 0 to 100 Electron Dynamics Ltd page 10 TC M Lite Temperature Controller User Manual V1 08 6 4 Sensor 6 4 1 Type The supported sensor types are selectable from the list box refer to the specification section 8 6 in this manual for supported temperature sensors 6 4 2 X2 X C Coefficients These are quadratic coefficients than
9. M51 LM60 LM61 e NTC Thermistors Suitable for PT100 sensors 100R accuracy 0 05 C Covers 200 C to 400 C range 2 2 CPU This provides all the intelligent control measuring the input values and calculating the output required for the control type It also provides storage for the configuration parameters 2 3 Output driver This provides a bi directional variable output drive to the TEC element s The output switches at the preset repetition rate and adjusting for output value by setting the PWM duty cycle 2 4 Communications A virtual com port is provided via a USB connection The latest driver for the onboard FTDI USB controller can be found at http www ftdichip com Drivers VCP htm 2 5 TEC Output The maximum TC M Lite output voltage to the TEC is that of the supplied TC M Lite input voltage It should be ensured that the input voltage supplied to the TC M Lite is less than the maximum specified input voltage for the TEC used A safety margin of 20 is advised Electron Dynamics Ltd page TC M Lite Temperature Controller User Manual V1 08 3 Connections The following section details the connections necessary for the TC M Lite The figures below show the pin out of the TC M Lite SENSOR TEMP_OK FAULT GND PWR S S GND TC M Lite viewed from top Micro USB PWR NC GND P P SUPPLY TEC N A in cased models Electron Dynamics Ltd age 3 TC M Lite Temperature Controller User Manu
10. aborts at the end and uses the new PID parameters for temperature control 5 7 Ziegler Nichols open loop step response This is open loop so there is no the control function is off it involves making a step change at the output The input thermal response should be noted then using graphical means should be analysed to give the initial process dead time and the process time constant From these the respective terms can be calculated Tdis Process time constant tis pseudo dead time and Kp the process gain From this the PID terms are calculated Ptermis 1 2 t Td Kp Itermis Td 0 5 and D termis Td 0 5 5 8 Ziegler Nichols closed loop ultimate gain method This is a closed loop so the control function in on With the P term set low and the term and D term off Monitoring the temperature the gain or P term is increased until there is sustained and continuous oscillation of the temperature The Gain P term required and the period of the oscillation should be noted From these the PID terms can be calculated Electron Dynamics Ltd page 7 TC M Lite Temperature Controller User Manual V1 08 Where Gu is the gain and Tu is the period From this the PID terms can be calculated Where P term 0 6 Gu term 0 5 Tu D term 0 125 Tu 6 Graphical User Interface The TC M Lite series Temperature Controller can be operated via Graphical User Interfaces one written in Java and the other in C They are very similar
11. al V1 08 3 1 Temperature Sensors 3 1 1 PT100 and PT1000 Measurements Connect PT100 sensor to J1 on pins 2 and 3 with screen to pin 4 3 1 2 Voltage sensor measurements For voltage outputs sensors LM35 LM50 LM51 LM60 LM61 configure the following links on the TC M Lite PCB Connect sensor to J1 Sensor to pin 2 sensor to pin 3 and sensor GND to pin 4 In this configuration LM35 operates down to zero degrees C but not below 3 1 3 NTC thermistors Connect thermistor to J1 between pins 2 and pins 3 connect screen to pin 4 if used For best operation use 10K types these have a better range in this circuit Other values can be accommodated if required Consult Electron Dynamics for possibilities 3 1 4 Other temperature sensors For requirements outside of the supported temperature sensors please consult Electron Dynamics for advice 3 2 TEC connection Connect to J5 pins 4 and 5 noting polarity actual drive polarity can be configured by software 3 3 Power connection Input voltage should be applied between J5 pin 1 and Pin 3 Pin 2 is reserved for future use and should be left unconnected 3 4 Alarm output This is provided from J4 this is active when low 3 5 USB This is provided from J5 Note this operates as a virtual COM port 3 6 Status Output The TC M Lite series temperature controller has two outputs that show the status of the controller The signals on J4 are available on the non cased TC M Lite version onl
12. can be input to convert the sensor voltage measured into a temperature This can be used for other sensors so that these can calibrated Where temperature v v X2 v X C v is measured sensor voltage and temperature is calculated temperature The C term allows the user to adjust shift the temperature to compensate for variations in sensor accuracy It can be seen that this value simply added to the temperature value So if your sensor was 1 degree out then make C 1 Also provided is buttons to decrease increase this value in 1 degree steps For NTC thermistors different parameters are required 6 4 3 NTC thermistors For NTC thermistors different parameters are required Beta as specified for thermistor type Resistance at 25 C C coefficient degree offset RI drive resistance on TCM 22000 as standard 6 4 4 Units The temperature can be displayed in degrees Centigrade Kelvin or Fahrenheit 6 5 Output 6 5 1 Polarity This sets the polarity of the output drive 6 5 2 Minimum Sets the minimum value limit of the output Range 0 to 1000 6 5 3 Maximum Sets the maximum value limit of the output Range 0 to 1000 Electron Dynamics Ltd page 11 TC M Lite Temperature Controller User Manual V1 08 6 5 4 Frequency Sets the PWM repetition frequency of the output drive Range 20 to 1000 Hz 6 6 Alarms 6 6 1 Minimum Alarm Sets the temperature below which the alarm is activated Select via check box to
13. d to attenuated high frequency noise 5 4 Tuning the PID parameters The PID parameters can be tuned using various methods There are many methods of tuning the PID parameters required some of these also allow you to tailor the response in certain ways Three popular methods are Relay feedback closed loop Ziegler Nichols open loop step response Ziegler Nichols closed loop ultimate gain method The basic methods are mentioned below however extensive materials are available for detailed explanation 5 5 Temperature test mode Temperature test mode introduces the option of having a series of set points according to which the control loops through after specified intervals characterized for each set point Along with that there exists a rate control Being associated with every set point this control defines the rate at which the next set point should be approached after the end of intended time interval A maximum of five different set points could be used at this mode 5 6 Relay Feedback Autotuning The TC M features an auto tuning function as standard using the relay feedback method this makes this tuning the TC M lite very easy The user is able to select the set point around which the auto tuning should occur and how long for the unit to make measurements The unit then sets up the relay feedback conditions under which oscillation occurs these peaks are analysed and from these the PID parameters are calculated The test
14. f the TC M Lite input supply For example to reduce a 12V supply to a maximum drive of 6V limits of 50 and 50 would be used If the supply was instead 9V and 6V drive limits were required 67 and 67 would be applied Electron Dynamics Ltd page 5 TC M Lite Temperature Controller User Manual V1 08 44 Important stability issues Facilitate faster settling time and response by reducing thermal mass of sample reduce distance between TEC and item being cooled Improve accuracy by locating sensor as near to cooled device as possible Reduce thermal load by reducing thermal feedback from heatsink to sample by using thermal insulation 5 Temperature Controlling 5 1 Off mode This is purely a mode in which under temperature control the output drive is off This is intended for diagnostics or to ensure a failsafe condition 5 2 On Off control This mode of temperature control is the most basic it benefits from being relatively easy to set up Simply specify the set point and dead band Whilst this method may be sufficient for some applications there are some problems with this approach due to full on full off nature of the output the temperature stability is relatively poor A second problem is that TEC is cycled fully heating and the fully cooling this may cause reliability issues with the TEC itself 5 3 PID Control PID control comprises of three elements Proportional Integral and Derivative and is well establi
15. ing a fan on the heatsink can decrease the thermal resistance to air by as much as 3 times and will give a significant improvement to thermal dissipation 4 1 2 Thermal Conduction It is important to ensure that there is a good thermal path between the Sample TEC and heatsink Not only does this provide good heat removal dissipation but will improve the temperature stability Also important is that the mating surfaces are reasonably flat and that just enough heatsink compound is used to make the thermal connection A misconception is that more compounds will be better however excessive thermal compound reduces the thermal connection compromising the temperature stability 4 2 Peltier Size This should be calculated from the manufacturer s selection It is important that the TEC is not driven beyond its maximum the device will certainly be damaged if the maximum current is exceeded Due to the nature of the peltier device as the drive is increased above between 60 and 80 of maximum it becomes progressively less efficient and in this situation will tend to just provide more local heating that heat pumping This can possibly lead to thermal runaway if the limit is not set We feel that there is little point in working the devices in their inefficient region and recommend that device are run at a maximum of 80 of maximum drive 4 3 Drive Limit The TC M Lite series allows the allocation of maximum TEC drive limits 100 represents the voltage o
16. l from 200 C to 100 C at up to 0 05 C stability Our controller can be setup or controlled from a PC via USB allowing access to output limits PID terms deviation alarms and operating modes Typical uses for any precise temperature control system include laser diodes infrared detection high gain amplifiers and cold plate assemblies The TC M Lite series temperature controller is suitable for controlling single and multiple TEC arrays It provides a pulse width modulated output which effective provides a continuously variable output for cooling and heating The TC M Lite is programmable from a PC allowing configuration and tuning to meet system requirements This configuration data is stored internally allowing standalone operation once programmed The interface and command set allow the unit to be controlled remotely in particular this allows changing of the set point and alarm temperature settings Electron Dynamics Ltd page 1 TC M Lite Temperature Controller User Manual V1 08 2 Controller Functions The controller has the following functional parts 2 1 Sensor measurement The input stage provides measurement for resistive and voltage output sensors These are measured by a sophisticated delta sigma ADC which gives excellent accuracy and noise suppression TC M Lite units can be supplied that support the following sensors e PT100 PTOOO Resistance Temperature Detectors RTD s e Voltage Sensors LM35 LM50 L
17. n will load the respective GUI category with the current condition of the TC M Lite Series Temperature Controller 6 8 2 Write Button The write button will load the TC M Lite Series Temperature Controller with the current conditions entered in to the GUls category 6 9 Figure TC M series Temperature Controller GUI Java 2 Temperature Controller 101 xi Electron Dynamics Temperature Controller Control Set Point Sensor PID Type Method Pot PC LMSO Type boo Proportional 0 00 Pot Range 0 00 x2 Coefficient 0 00 Integral 0 00 Pot Offset 0 00 X Coefficient 0 00 Derivative 0 00 PC Set Paint 0 00 C Coefficient 0 00 Derivative Filter Control Centigrade Unit 0 00 Dead Band jooo Output Request Update Update Request Update Output Alarms i Report Polarity Negative 8 Positive le 0 01 Minimum Alarm 0 00 Set Point lo 00 Minimum o m 0 00 Maximum Alarm 0 00 Temperature 0 00 Maximum 0 00 Minimum Temperature Of Control 20 Frequency 0 00 Maximum Temperature 0 00 Output None Alarms None Faults Request Update Request Update Request Not Connected Electron Dynamics Ltd page 13 TC M Lite Temperature Controller User Manual V1 08 6 10 C GUI There are minor differences with the Java GUI as below 6 10 1 Additional features The C
18. re gt set point dead band Fully Cooling Temperature lt set point dead band Fully Heating Temperature lt set point dead band and gt set point dead band output off 6 2 4 Proportional With proportional action the controller output is proportional to the temperature error from the setpoint The proportional terms sets the gain for this where Output set point actual temperature proportional term 6 2 5 Integral With integral action the controller output is proportional to the amount of time the error is present Integral action eliminates offset The integral term is a time unit in seconds NB for larger effects of integration reduce the integral time also for operation without integral integral time can be set to a large number e g 1 000 000 6 2 6 Derivative With derivative action the controller output is proportional to the rate of change of the measurement or error The controller output is calculated by the rate of change of the measurement with time in seconds Increasing the derivative value will result in an increased derivative action See also Derivative Filter Electron Dynamics Ltd page 9 TC M Lite Temperature Controller User Manual V1 08 6 2 7 Derivative Filter The derivative filter is a low pass filter function on the derivative value This allows the filtration of noise components which are a problem with a pure derivative function The filter value should be set to between 0 and
19. scsssssssssseseceseeeeeeseeeseaesesssessaeasacasaseeesenensseseesens 7 6 6 Relay Resdback AUTO UNI cesa Heme Seta laced eterna alae 7 6 7 Ziegler Nichols open loop Step reSPONSE ceccceseseceseeececeeeeestetstseseetsnsteeens 7 6 8 Ziegler Nichols closed loop ultimate gain method 7 7 Graphical User IMC ACS aii A A AE RDA 8 7 1 lt DoW Men s o 8 TAM Pl MU dei aid 8 A e a a e 8 A A A ON ah 8 7 2 A E anh tie sea eantenci E E 9 py AAA A steer erry ie tr arora eer er 9 AO AAA A A A oe ae eal taal Aes 9 Taa SOMO nea sa Bct cae ceeds ss E ast teed EEEE E E G 9 A EA church A eee 9 A O 9 PRO III A A SM aA san AD 9 ELE Derivative abad 10 A Dead A A E E et oa A 10 129 POWER AAA A A 10 7 3 O A Te 10 Electron Dynamics Ltd page 1 TC M Lite Temperature Controller User Manual V1 08 E A ne eat 10 Teo PORIN eiaa es oat ace eke ae 10 fe Pi O A A A 10 T34 E A A O tegatana dea As 10 Ys Ho O AA an 10 E A cal aaa a a a Eich 10 74 A OR 11 LAN Di aii 11 CERO Y MAL AAA trenton again taunts 11 7 4 3 NTC thermistors AAA CO 11 US taa 11 7 5 A a a a Teer grea terete met 11 eea ao E a Ea E E E a A EE ea E E 11 A III rai alada 11 PS MAMA 11 PAL SETCQUGIGY aicecise ssa A E 12 7 6 AMS a aba 12 OI gt MIRIAM sa 12 7 6 2 MAMA a 12 7 6 3 Minimum OK Temperature aiii A tt Sau doh ches as 12 7 6 4 Maximum Temperature atada 12 7 6 5 Operational temperature max Only available on certain GU
20. shed as being the foremost temperature control method The Proportional term provides a variable output which as the temperature deviates further from the set point then the output drive increases until the maximum is reached The response of this is defined by the value of the P term Output set point actual temperature proportional term The main issue with a purely Proportional response is that there is always a steady state temperature error This is due to the fact that in order to provide an output then there needs to be a temperature error Using an integral term overcomes the problem of steady state errors practically it accumulates any error and applies this to the output drive to compensate Increasing or decreasing it accordingly Though there are direct benefits in temperature accuracy there is some sacrifice in system stability particularly as the integral effect is increased The derivative term provides an output proportion which varies with the rate of the input error or output This provides a faster response to temperature variations and also provides a stability balancing effect to the integral term Please note that for best stability there must be a fixed ratio between the term and the D term normally 4 to 1 Electron Dynamics Ltd page 6 TC M Lite Temperature Controller User Manual V1 08 Due to the inherently large gain of the derivative at high frequencies at filter the derivative TC is provide
21. y TEMP OK Pin 1 HIGH Temperature ok in relation to set point and user defined settings TEMP OK Pin 1 LOW Temperature out of range Fault Pin 2 HIGH Temperature controller working correctly Fault Pin 2 LOW Indicates an alarm or inhibit External or Internal Electron Dynamics Ltd page 4 TC M Lite Temperature Controller User Manual V1 08 4 Thermal Issues 4 1 Thermal Assembly This is a critical component in the system design typically there are 2 potential pitfalls the heatsink is not large enough the thermal conduction between components is poor It is worth reading the extensive material available from the peltier TEC manufacturers to find out the requirements for this See www marlow com and www lairdtech com 4 1 1 Heat sink size The size of this should be chosen using the manufacturer s calculations it will need to be large enough to radiate the heat required Typically they have a large heat capacity but often are more limited in their capability to dissipate the heat This is often seen when operating under temperature control there is a continuous rise in heatsink temperature or rise in drive current It should be noted that there is a point in where the system can go into thermal runaway as the heatsink is unable to dissipate the heat properly and the temperature of the sample and heatsink will continuously climb Heatsink dissipation capacity should be chosen to be larger than necessary Us
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