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Problem

Causes and Solutions

The controller controls or
attempts to control at an
inaccurate temperature

If the controller appears to operate normally except that the bath’s temperature
does not agree with the temperature measured by the user’s reference ther-
mometer to within the specified accuracy, consider the following:

Erroneous parameters.

Check that the calibration parameters are all correct

according to the Report of Test. If not, reprogram the constants. If the controller
does not keep the correct parameters, the memory backup battery may be
weak causing errors in data. See “Low Battery” in a previous solution.

Poor uniformity.

There may be an actual difference between the bath’s control

probe and the reference thermometer due to excess gradients in the bath.
Check that the bath has an adequate amount of fluid in the tank and that the
stirrer is operating properly. Also check that the reference thermometer and
control probe are both fully inserted into the bath to minimize temperature gradi-
ent errors.

Defective control probe.

Check that the control probe has not been struck,

bent, or damaged. Refer to the previous solution for how to check the probe’s
resistance.

The controller shows that
it is controlling at the
proper temperature, but
the bath temperature is
unstable

If the bath does not achieve the expected degree of temperature stability when
measured using a thermometer, consider the following:

Wrong proportional band setting.

If the proportional band is set too narrow,

the bath will oscillate causing poor stability. In this case, increase the width of
the proportional band.

If the proportional band setting is too wide, the long-term stability of the bath is
affected. In this case decrease the width of the band. (Refer to Section 9.7.)

Bath fluid is too thick.

Make sure that the bath fluid used is less than 50 centi-

Stokes (10 is ideal) at the temperature at which the bath is controlling. Check
the fluid manufacturer’s specifications.

You should also change the bath fluid regularly and if it changes colors or be-
comes too thick.

Defective control probe.

Check that the control probe has not been struck,

bent, or damaged. Refer to the previous solution for how to check the probe’s
resistance.

The controller alternately
heats for a while then
cools

Wrong proportional band setting.

If the proportional band is set too narrow,

the bath will oscillate between too much heating and too much cooling causing
instability. Increase the width of the proportional band until the temperature sta-
bilizes. (Refer to Section 9.7.)

The bath does not
achieve low temperatures

Insufficient cooling

. This may be caused by lack of refrigerant because of a

leak in the system. Refer to Section 12, Charging Instructions.

77

14 Troubleshooting

Troubleshooting

Содержание 7312

Страница 1: ...ch 2013 2013 Fluke Corporation All rights reserved Specifications are subject to change without notice All product names are trademarks of their respective companies Via Acquanera 29 22100 Como tel 031 526 566 r a fax 031 507 984 info calpower it www calpower it ...

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Страница 4: ... 34 8 1 10 Commonly Used Fluids 34 8 1 10 1 Water 34 8 1 10 2 Ethylene Glycol 34 8 1 10 3 Mineral Oil 34 8 1 10 4 Silicone Oil 34 8 1 11 Fluid Characteristics Charts 35 8 1 11 1 Limitations and Disclaimer 35 8 1 11 2 About the Graph 35 8 2 Stirring 37 8 3 Power 38 8 4 Heater 38 8 5 Temperature Controller 38 8 6 Refrigeration 39 9 Controller Operation 41 9 1 Bath Temperature 41 9 2 Reset Cutout 41 ...

Страница 5: ...Digital Communication Interface 57 10 1 Serial Communications 57 10 1 1 Wiring 57 10 1 2 Setup 58 10 1 2 1 BAUD Rate 58 10 1 2 2 Sample Period 59 10 1 2 3 Duplex Mode 59 10 1 2 4 Linefeed 59 10 1 3 Serial Operation 59 10 2 IEEE 488 Communication optional 59 10 2 1 Setup 60 10 2 1 1 IEEE 488 Address 60 10 2 1 2 Transmission Termination 60 10 2 2 IEEE 488 Operation 60 10 3 Interface Commands 60 10 4...

Страница 6: ...nt of Water Cutout 68 12 Charging Instructions 71 12 1 Leak Testing 71 12 2 Evacuation 71 12 3 Charging 71 13 Maintenance 73 14 Troubleshooting 75 14 1 Troubleshooting 75 14 2 Comments 78 14 2 1 EMC Directive 78 14 2 2 Low Voltage Directive Safety 78 iv ...

Страница 7: ...Figure 3 Fluid Level 25 Figure 4 Location of Handles for NBS Design Cells 26 Figure 5 Front Controller Panel 29 Figure 6 Chart of Various Bath Fluids and Their Properties 37 Figure 7 Controller Operation Flowchart 42 Figure 8 Bath Temperature Fluctuation at Various Proportional Band Settings 47 Figure 9 Serial Communications Cable Wiring 58 Figure 10 Sample Calibration Computations 67 ...

Страница 8: ...International Electrical Symbols 1 Table 2 Table of Various Bath Fluids and Their Properties 36 Table 3 Proportional Band Fluid Table 48 Table 4 Interface Command Summary 61 Table 4 Interface Command Summary continued 62 ...

Страница 9: ...the instrument or in this manual Symbol Description AC Alternating Current AC DC Battery CE Complies with European Union Directives DC Double Insulated Electric Shock Fuse PE Ground Hot Surface Burn Hazard Read the User s Manual Important Information Off On 1 1 Before You Start Symbols Used Table 1 International Electrical Symbols ...

Страница 10: ...1 2 1 WARNINGS To avoid possible electric shock or personal injury follow these guidelines GENERAL DO NOT use the instrument for any application other than calibration work The instrument was designed for temperature calibration Any other use of the unit may cause unknown hazards to the user DO NOT use the unit in environments other than those listed in the user s guide DO NOT overfill the bath Ov...

Страница 11: ...This instrument must be plugged into a 115 VAC 60Hz 230 VAC 50Hz optional AC only electric outlet The power cord of the instrument is equipped with a three pronged grounding plug for your protection against electrical shock hazards It must be plugged directly into a properly grounded three prong receptacle The receptacle must be installed in accordance with local codes and ordi nances Consult a qu...

Страница 12: ...se before placing the unit into service DO NOT change the values of the bath calibration constants from the fac tory set values The correct setting of these parameters is important to the safety and proper operation of the unit The refrigeration may be damaged or the lifetime shortened if the set point temperature is set above 60 C for more than one hour with the refrigeration manually on Ensure t...

Страница 13: ...at the bath is energized or when it is moved from one location to another Turning the bath ON or OFF does not trigger the delay If a High Low voltage condition exists for longer than 5 seconds the bath de energizes An amber indicator on the back panel lights when this con dition exists Re energization is automatic upon correction of the fault condition and af ter a delay cycle of about 2 minutes I...

Страница 14: ...wai Dajie Chao Yang District Beijing 100004 PRC CHINA Phone 86 10 6 512 3436 Telefax 86 10 6 512 3437 E mail xingye han fluke com cn Fluke South East Asia Pte Ltd Fluke ASEAN Regional Office Service Center 60 Alexandra Terrace 03 16 The Comtech Lobby D 118502 SINGAPORE Phone 65 6799 5588 Telefax 65 6799 5588 E mail antng singa fluke com When contacting these Service Centers for support please have...

Страница 15: ... Serial Number Voltage Complete description of the problem 7 1 Before You Start Authorized Service Centers ...

Страница 16: ...execute the many operating functions User interface is provided by the 8 digit LED display and four key switches Digital remote communications is standard with an RS 232 serial interface and optional with an IEEE 488 interface Temperature cutouts protect triple point of water cells from freezing or high temperatures due to system failure Separate circuits cut off heating or refriger ation independ...

Страница 17: ...on Package Interface it software and an RS 232 computer interface are available for setting the bath temperature via an external computer For IEEE 488 add 2001 IEEE to the automation package Safety OVERVOLTAGE Installation CATEGORY II Pollution Degree 2 per IEC1010 1 3 2 Environmental Conditions Although the instrument has been designed for optimum durability and trou ble free operation it must be...

Страница 18: ......

Страница 19: ...ng any item please call an Authorized Service Center for assistance 4 2 Set Up CAUTION The drain valve must be installed on the back of the bath be fore attempting to fill the tank with fluid See Section 5 3 on page 17 for drain installation instructions WARNING The instrument is equipped with a soft cutout user settable firmware and a hard cutout set at the factory Check the flash point boiling p...

Страница 20: ...each the previously programmed temperature set point The front panel LED display indicates the actual bath temperature Set the cooling switch to OFF for tem perature above approximately 45 C Set the switch to ON for lower temperatures 4 4 Setting the Temperature In the following discussion and throughout this manual a solid box around the word SET UP DOWN or EXIT Indicates the panel button to pres...

Страница 21: ...mperature display 24 73 C Bath temperature display The bath heats or cools until it reaches the new set point temperature Turn off the cooling to reach and control at higher temperatures When setting the set point temperature be careful not to exceed the temperature limit of the bath fluid The over temperature cutout should be correctly set for added safety See Section 9 8 Cutout To obtain optimum...

Страница 22: ...e than 10 days the bath needs to be energized for a dry out period of 1 2 hours before it can be assumed to meet all of the safety require ments of the IEC 1010 1 5 3 Bath Preparation and Filling CAUTION Before filling the tank with fluid the drain valve must be in stalled onto the pipe fitting at the back of the bath 5 3 1 Drain Valve Installation Instructions The drain valve attaches to the swag...

Страница 23: ...nant packing materials etc Fill the bath with clean unpolluted fluid Fill the bath carefully through the large rectangular access hole to a level that allows for stirring and thermal ex pansion Section 9 1 5 Thermal Expansion explains fluid expansion DO NOT turn on the bath without fluid in the tank Maximum and minimum fill levels are dependent on the application whether it is used for TPW cells o...

Страница 24: ...frequency and current capacity Refer to Section 3 1 Specifications for power details Refer to and read the caution at the front of the manual concerning brownout and over voltage protection Check the back panel label for the correct voltage and frequency prior to energizing the unit 19 5 Installation Power ...

Страница 25: ...ly hot or cold when removed from the bath Cautiously handle probes to prevent personal in jury Carefully place probes on a heat cold resistant surface or rack until they are at room temperature It is advisable to wipe the probe with a clean soft cloth or paper towel before inserting it into another bath This prevents the mixing of fluids from one bath to another If the probe has been calibrated in...

Страница 26: ...ise if the ice mantle seems to be melting back lower the temperature 6 2 3 Adjusting the TPW Cell Rack The 7312 bath is provided with two adjustable racks that provide stable loca tion for the cells See Figure 2 Remove the racks by reaching in and withdraw ing them The stainless steel baffles on the left and right sides of the tank act as guides or tracks to locate and retain each rack A TPW rack ...

Страница 27: ...e Location Adjusting Set Screws TPW Cells Baffle Guide Location Support Rods Bottom Plate Top Plate Adapter Removable Guide Tubes Access Cover Rubber Shock Guides Thermometer Precooling Holes Rubber Grommet Figure 2 Details of the Access Cover and Cell Racks ...

Страница 28: ...de at the top to help reduce shock strain to the del icate platinum sensor in an SPRT Underneath the cover a guide tube helps to prevent the thermometer from contacting internal parts If the thermometer is longer than 20 inches the user must retain it to prevent it from striking the bottom The two wells in the front permit thermometers to gain access to the TPW cells They also feature the rubber s...

Страница 29: ...25 6 Bath Use Triple Point of Water Cell Maintenance Fluid Level in Bath Figure 3 Fluid Level ...

Страница 30: ...use This freedom of movement means that there is a thin layer of water all around the reentrant tube If it is not free to move small errors result in the acquired temperature Insert a room temperature rod into the fluid in the reentrant tube transferring heat to the ice until the mantle moves freely This movement can be checked by rotating the cell quickly around its long axis The ice tends to sta...

Страница 31: ...bration at high temperatures a heat shield could be used just below the probe handle This heat shield could be as simple as aluminum foil slid over the probe before inserting it in the bath or as complicated as a specially designed reflective metal apparatus When calibrating over a wide temperature range starting at the highest temper ature and progressing down to the lowest temperature can genera...

Страница 32: ...access and set other operating parameters and access and set bath calibration parameters A brief description of the functions of the buttons follows SET Used to display the next parameter in a menu and to set parameters to the displayed value DOWN Used to decrement the displayed value of parameters UP Used to increment the displayed value EXIT Used to exit from a menu When the EXIT button is press...

Страница 33: ...e and acti vates the low temperature cutout to turn off the refrigeration below a pre set temperature in case of temperature controller failure This feature is intended to protect triple point of water cells The stirring motor is mounted on the bath tank lid It drives the stirring propeller to provide mixing of the bath fluid Proper mixing of the fluid is important for good constant temperature st...

Страница 34: ...the safe operating temperature limit of the fluid 8 1 2 Viscosity Viscosity is a measure of the thickness of a fluid or how easily it can be poured and mixed Viscosity affects the temperature uniformity and stability of the bath With lower viscosity fluid mixing is better creating a more uniform tem perature throughout the bath This improves the bath response time allowing it to maintain a more co...

Страница 35: ...luids Fluid manufacturers can also provide this information The ther mal expansion coefficients are shown in units of cm cm C however the values are the same for any units of length Divide the value by 1 8 for F coefficients The following equation may be used to find the desired depth De Ds K Te Ts 1 Or Ds De K Te Ts 1 where De or The Maximum Fill Depth Where K Expansion coefficient Te Ending Temp...

Страница 36: ...r fume hood must be used if hazardous or bothersome vapors are produced WARNING Fluids at high temperatures may pose danger from BURNS FIRE and TOXIC FUMES Use appropriate caution and safety equip ment Fluids may be flammable and require special fire safety equipment and proce dures An important characteristic of the fluid to consider is the flash point The flash point is the temperature at which ...

Страница 37: ...contamination 8 1 10 2 Ethylene Glycol The temperature range of water may be extended by using a solution of one part water and one part ethylene glycol antifreeze The characteristics of the ethylene glycol water solution are similar to water but with higher viscosity Use caution with ethylene glycol since this fluid is very toxic Ethylene glycol must be disposed of properly 8 1 10 3 Mineral Oil M...

Страница 38: ...Hart Scientific cannot be liable for any personal injury or damage to equipment product or facilities resulting from the use of these fluids The user of the bath is responsible for collecting correct information exercising proper judgment and insuring safe operation Operating near the limits of certain properties such as the flash point or viscos ity can compromise safety or performance Your compa...

Страница 39: ... 75 C 0 57 125 C 0 00025 25 C 0 0007 50 C 5 25 C Silicone Oil Type 200 05 5010 40 C v 130 C fl cc 133 C 5 25 C 0 92 25 C 0 4 0 00028 25 C 0 00105 1000 25 C 10 150 C Silicone Oil Type 200 10 5012 30 C v 209 C fl cc 211 C 10 25 C 3 135 C 0 934 25 C 0 43 40 C 0 45 100 C 0 482 200 C 0 00032 25 C 0 00108 1000 25 C 50 150 C Silicone Oil Type 200 20 5013 10 C v 230 C fl cc 232 C 20 25 C 0 949 25 C 0 370 ...

Страница 40: ... Freeze Point PP Pour Point Shaded area represents usable range of fluid starting at 50 centistokes Lighter shading represents decreasing viscosity while vaporization and decomposition increase Black area represents liquid range with excessive viscosity Range over which a fume hood is recommended 10 CS FL 302 C PP Silicone Oil 5017 Silicone Oil 5014 10 CS FL 280 C PP Silicone Oil 5013 10 CS FL 232...

Страница 41: ... relay The front panel red green control indicator shows the state of the heater The control indicator glows red when the heater is on and glows green when the heater is off The indicator pulses constantly when the bath is maintaining a sta ble temperature 8 5 Temperature Controller Hart Scientific s unique hybrid digital analog temperature controller controls the bath temperature The controller o...

Страница 42: ...Interface When the controller is set to a new set point the bath heats or cools to the new temperature Once the new temperature is reached the bath usually takes 10 15 minutes for the temperature to settle and stabilize There may be a small over shoot or undershoot of about 0 5 C 8 6 Refrigeration Bath cooling below 50 C is provided by a compact refrigeration system The system utilizes the ozone s...

Страница 43: ... degrees Celsius The temperature display function may be accessed from any other function by pressing the EXIT button 9 2 Reset Cutout If the over temperature cutout has been triggered the temperature display alter nately flashes cut out Indicates cutout condition The message continues to flash until the temperature is reduced and the cutout is reset The cutout has two modes automatic reset and ma...

Страница 44: ...le Period Adj Sample Period Duplex Mode Adj Duplex Mode Linefeed Adjust Linefeed EXIT EXIT EXIT EXIT EXIT EXIT EXIT EXIT EXIT EXIT SET Display Power Set Proportional Band Set Cutout Temp EXIT EXIT EXIT SET SET SET SET SET SET SET SET SET SET Reset Cutout Select Setpoint Adjust Setpoint EXIT EXIT Adjust Vernier Set Scale C F Cutout Active Display Temperature Cutout Reset Mode Adj Cutout Reset Mode ...

Страница 45: ...uid Setting the bath temperature involves three steps 1 selecting the set point memory 2 adjusting the set point value and 3 adjusting the vernier if desired 9 3 1 Programmable Set points The controller stores 8 set point temperatures in memory The set points can be quickly recalled to conveniently set the bath to a previously programmed tem perature set point To set the bath temperature first sel...

Страница 46: ...he user may want to adjust the set point slightly to achieve a more precise bath temperature The set point vernier allows one to adjust the temperature below or above the set point by a small amount with a very high resolution Each of the eight stored set points has an associated vernier setting The vernier is accessed from the set point by pressing the SET button The vernier setting is displayed ...

Страница 47: ...the vernier adjustment function by pressing the SET button From the temperature display function access the units selection by pressing SET 4 times 25 0 Bath temperature S Access et point memory 1 25 0 Set point memory S Access set point value C 25 00 Set point value S Access vernier 0 00000 Vernier setting S Access scale units selection Un C Scale units currently selected Press the UP or DOWN but...

Страница 48: ... heater power is displayed as a percentage of full power S E Access heater power in secondary menu 12 Pct Heater power in percent To exit out of the secondary menu press the EXIT button To continue on to the proportional band setting press the SET button E Return to temperature display 9 7 Proportional Band In a proportional controller such as this the heater output power is proportional to the ba...

Страница 49: ...tting is used so that the change in output power per change in temperature remains the same The proportional band should also be wider when the fluid viscosity is higher be cause of the increased response time The proportional band width is easily adjusted from the bath front panel The width may be set to discrete values in degrees C or F depending on the selected units The optimum proportional ba...

Страница 50: ...WN buttons D Decrement display Pb 0 060C New proportional band setting To accept the new setting and access the cutout set point press the SET but ton Pressing the EXIT button exits the secondary menu ignoring any changes just made to the proportional band value S Accept the new proportional band setting 7312 TPW Maintenance Bath User s Guide 48 Fluid Temperature Proportional Band Stability Water ...

Страница 51: ... a few degrees below the cutout set point temperature At this point the action of the cutout is determined by the setting of the cutout mode parameter The cutout has two selectable modes automatic reset or manual reset If the mode is set to automatic the cutout automatically resets when the bath temper ature falls below the reset temperature allowing the bath to heat up again If the mode is set to...

Страница 52: ...arameters menu contains the parameters D0 and DG which characterize the resistance temperature rela tionship of the thermistor control probe These parameters may be adjusted to improve the accuracy of the bath This procedure is explained in detail in Sec tion 11 The probe parameters are accessed by pressing the SET button after the name of the parameter is displayed The value of the parameter may ...

Страница 53: ...ages the refrigeration compressor If the probe is replaced the cutout board must be recalibrated See Section 12 The user may set the cutout temperature A typical set point is from 0 3 to 0 5 C If undesired trips occur the temperature may be reduced The adjustment range is 1 27 C from 0 C in 0 01 C increments The triple point of water cutout engages for three reasons 1 the controller does not send ...

Страница 54: ...s The serial RS 232 interface parameters menu is indicated by SErIAL Serial RS 232 interface parameters menu The serial interface parameters menu contains parameters which determine the operation of the serial interface The parameters in the menu are BAUD rate sample period duplex mode and linefeed 9 12 1 BAUD Rate The BAUD rate is the first parameter in the menu The BAUD rate setting de termines ...

Страница 55: ...ds Adjust the value with the UP or DOWN button and then use the SET button to set the sample rate to the displayed value SA 60 New sample period 9 12 3 Duplex Mode The next parameter is the duplex mode The duplex mode may be set to full du plex or half duplex With full duplex any commands received by the bath via the serial interface are immediately echoed or transmitted back to the device of orig...

Страница 56: ...ted with the interface The menu is indicated by IEEE IEEE 488 parameters menu Press the SET button to enter the menu 9 13 1 IEEE 488 Address IEEE 488 interface must be configured to use the same address as the external communicating device The address is indicated by AddrESS IEEE 488 interface address Press the SET button to access the address setting Add 22 Current IEEE 488 interface address Adju...

Страница 57: ...ller s memory fails The user may then restore these values to the factory settings A list of these constants and their settings are supplied to the user on the Report of Test with the manual CAUTION DO NOT change the values of the bath calibration constants from the factory set values The correct setting of these parameters is im portant to the safety and proper operation of the bath The calibrati...

Страница 58: ...present danger of the bath exceeding its temperature range causing damage or fire 7312 TPW Maintenance Bath User s Guide 56 ...

Страница 59: ...ion the cooling may be controlled using the interface To control the cooling with the interface the cooling power switch must be OFF 10 1 Serial Communications The RS 232 serial interface allows serial digital communications over fairly long distances 15 24 meters With the serial interface the user may access any of the functions parameters and settings discussed in Section 10 Controller Operation...

Страница 60: ...secondary menu Press the SET button repeatedly until the display reads ProbE This is the menu selection Press the UP button repeatedly until the serial interface menu is in dicated with SErIAL Finally press the SET button to enter the serial pa rameter menu The serial interface parameter menu contains the BAUD rate the sample rate the duplex mode and the linefeed parameter 10 1 2 1 BAUD Rate The B...

Страница 61: ... are immedi ately echoed or transmitted back to the device of origin With half duplex the commands are executed but not echoed The default setting is full duplex The mode may be changed using UP or DOWN and pressing SET 10 1 2 4 Linefeed The final parameter in the serial interface menu is the linefeed mode This pa rameter enables On or disables OFF transmission of a linefeed charac ter LF ASCII 10...

Страница 62: ...tting Press the SET button to save the new selection 10 2 2 IEEE 488 Operation Commands may now be sent via IEEE 488 interface to read or set the tempera ture or access other controller functions All commands are ASCII character strings and are terminated with a carriage return CR ASCII 13 Interface commands are listed below 10 3 Interface Commands The various commands for accessing the bath contr...

Страница 63: ...portional band setting pr op band pr pr 999 9 pr 15 9 Set proportional band to n pr op band n pr 8 83 Depends on Configuration Read cut out setting c utout c c 9999 x xxx c 110 C in Set cut out setting c utout n r eset Set cut out to n degrees c utout n c 110 Temperature Range Reset cut out now c utout r eset c r Read heater power duty cycle po wer po po 9999 po 1 Configuration Menu Probe Menu Rea...

Страница 64: ...erial linefeed mode to on lf eed on lf on Set serial linefeed mode to off lf eed of f lf of Calibration Menu Read low set point limit value tl ow tl tl 999 tl 80 Set low set point limit to n tl ow n tl 80 5 to 25 C Read high set point limit value th igh th th 999 th 205 Set high set point limit to n th igh n th 205 25 to 110 C Miscellaneous not on menus Read firmware version number ver sion ver ve...

Страница 65: ...th To allow the interface to control the cooling disable the front panel con trols by switching the refrigeration switch to OFF Otherwise the interface would not be able to switch these functions off To control the refrigeration power with the digital interface the front panel re frigeration switch must be off The refrigeration power function is controlled with the F2 command Setting the F2 value ...

Страница 66: ...y of say 0 2 C over the range 20 to 80 C Choosing 30 C and 70 C may allow the bath to have a better accuracy of maybe 0 05 C over the range 30 to 70 C but outside the range the accuracy may be only 0 5 C 11 2 Measuring the Set point Error The first step in the calibration procedure is to measure the temperature errors including sign at the two calibration temperatures First set the bath to the low...

Страница 67: ... within this range The current val ues for D0 and DG are 25 229 and 186 974 respectively The calibration points are chosen to be 25 00 and 75 00 C The measured bath temperatures are 24 869 and 74 901 C respectively Refer to Figure 10 for applying the equa tions to the example data and computing the new probe constants 11 5 Single Point Calibration When calibrating the bath for applications emphasi...

Страница 68: ...bilize at that temperature Check the bath stability with the thermometer When both the bath and the thermometer have stabilized measure the bath temperature with the thermometer and compute the temperature error which is the set point temperature minus the actual bath temperature Error Tsp Tactual 67 11 Calibration Procedure Measuring the Set point Error D0 25 229 DG 0 0028530 tL 25 00 C measured ...

Страница 69: ...der temperature cutout is provided to protect the triple point of water cell in case there is a temperature controller or sensor failure that would cause the bath to cool rapidly below the set point temperature Such a failure could cause the cell to rupture due to rapid expansion of the ice inside it The cutout deactivates the refrigeration thereby preventing the problem CAUTION Only trained perso...

Страница 70: ...e bath and allow the bath to regain stable control at the required set point This procedure takes 15 minutes or longer de pending on how long the bath has been off and how far it has drifted off tem perature Be aware that the bath has a low voltage line monitor that activates when the power is disconnected Several minutes are required before the unit is permitted to turn on Note the amber light on...

Страница 71: ...em open for more than 15 minutes Polyolester oils are very hygroscopic Evacuate the system to a minimum of 200 microns Evacuate from both high and low sides of the system Schrader valves provide access to the system 12 3 Charging After evacuation charge the system with 160 grams of R 134a Set the suction pressure to 8 10 psig for operation NOTE A fan must be placed in front of the condenser if the...

Страница 72: ...uld be checked at least every month for the first year and regularly thereafter This fluid check provides a baseline for knowledge of bath operation with clean usable fluid Once some fluids have become compromised the break down can occur rap idly Particular attention should be paid to the viscosity of the fluid A sig nificant change in the viscosity can indicate that the fluid is contaminated bei...

Страница 73: ...ath may be impaired or safety hazards may arise The over temperature cutout should be checked every 6 months to see that it is working properly In order to check the user selected cutout follow the controller directions Section 10 2 for setting the cutout Both the manual and the auto reset option of the cutout should be checked Set the bath temperature higher than the cutout Check to see if the di...

Страница 74: ...ompres sor is de energized and the Mains Out of Range light on the back panel illumi nates indicating a fault condition Re energization is automatic upon correction of the fault condition and after a delay cycle of about 2 minutes High and low voltage protection limits at 115 VAC Voltage Cutout 12 5 101 129 VAC Voltage Cutin 7 5 106 124 VAC High and low voltage protection limits at 230 VAC Voltage...

Страница 75: ... is manually reset the cutout circuitry may be faulty Try per forming the Factory Reset Sequence explained below Factory Reset Sequence Hold the SET and EXIT keys down at the same time while powering up the unit The display shows init the model number and the firmware version Each of the controller parameters and calibration con stants must be re programmed The values can be found on the Report of...

Страница 76: ...s unstable If the bath does not achieve the expected degree of temperature stability when measured using a thermometer consider the following Wrong proportional band setting If the proportional band is set too narrow the bath will oscillate causing poor stability In this case increase the width of the proportional band If the proportional band setting is too wide the long term stability of the bat...

Страница 77: ...e cycle count shows a low number such as 0002 the battery is spent and should be replaced Contact an Authorized Ser vice Center for assistance 5 After replacing the battery you must reprogram the calibration and user ad justable parameters into the controller 14 2 Comments 14 2 1 EMC Directive Hart Scientifics equipment has been tested to meet the European Electromag netic Compatibility Directive ...

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